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Wu J, Liu L, Wang J, Wang Y, Li X, Wang X, Jiang S, Li W, Zhang J, Zhang X. Transcriptomic analysis of induced resistance to polymyxin in carbapenem-resistant Enterobacter cloacae complex isolate carrying mcr-9. J Glob Antimicrob Resist 2024; 37:225-232. [PMID: 38750896 DOI: 10.1016/j.jgar.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 03/17/2024] [Accepted: 04/15/2024] [Indexed: 06/06/2024] Open
Abstract
OBJECTIVES Polymyxins are currently the last-resort treatment against multi-drug resistant Gram-negative bacterial infections, but plasmid-mediated mobile polymyxin resistance genes (mcr) threaten its efficacy, especially in carbapenem-resistant Enterobacter cloacae complex (CRECC). The objective of this study was to provide insights into the mechanism of polymyxin-induced bacterial resistance and the effect of overexpression of mcr-9. METHODS The clinical strain CRECC414 carrying the mcr-9 gene was treated with a gradient concentration of polymyxin. Subsequently, the broth microdilution was used to determine the minimum inhibitory concentration (MIC) and RT-qPCR was utilized to assess mcr-9 expression. Transcriptome sequencing and whole genome sequencing (WGS) was utilized to identify alterations in strains resulting from increased polymyxin resistance, and significant transcriptomic differences were analysed alongside a comprehensive examination of metabolic networks at the genomic level. RESULTS Polymyxin treatment induced the upregulation of mcr-9 expression and significantly elevated the MIC of the strain. Furthermore, the WGS and transcriptomic results revealed a remarkable up-regulation of arnBCADTEF gene cassette, indicating that the Arn/PhoPQ system-mediated L-Ara4N modification is the preferred mechanism for achieving high levels of resistance. Additionally, significant alterations in bacterial gene expression were observed with regards to multidrug efflux pumps, oxidative stress and repair mechanisms, cell membrane biosynthesis, as well as carbohydrate metabolic pathways. CONCLUSION Polymyxin greatly disrupts the transcription of vital cellular pathways. A complete PhoPQ two-component system is a prerequisite for polymyxin resistance of Enterobacter cloacae, even though mcr-9 is highly expressed. These findings provide novel and important information for further investigation of polymyxin resistance of CRECC.
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Affiliation(s)
- Jiming Wu
- Department of Microbiology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China
| | - Longjin Liu
- Department of Microbiology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China
| | - Jianmin Wang
- Department of Microbiology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China
| | - Ying Wang
- Department of Microbiology, The First Affiliated Hospital of Jiamusi University, Jiamusi, China
| | - Xinhui Li
- Department of Microbiology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China
| | - Xiaoyu Wang
- Department of Microbiology, The First Affiliated Hospital of Jiamusi University, Jiamusi, China
| | - Shan Jiang
- Department of Pathogenic Biology, Basic Medicine of Jiamusi University, Jiamusi, China
| | - Wengang Li
- Department of Pathogenic Biology, Basic Medicine of Jiamusi University, Jiamusi, China
| | - Jisheng Zhang
- Department of Microbiology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China.
| | - Xiaoli Zhang
- Department of Microbiology, Yongchuan Hospital of Chongqing Medical University, Chongqing, China
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Wang CH, Siu LK, Chang FY, Tsai YK, Huang LY, Lin JC. Influence of PhoPQ and PmrAB two component system alternations on colistin resistance from non-mcr colistin resistant clinical E. Coli strains. BMC Microbiol 2024; 24:109. [PMID: 38565985 PMCID: PMC10986093 DOI: 10.1186/s12866-024-03259-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 03/14/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND The current understanding of acquired chromosomal colistin resistance mechanisms in Enterobacterales primarily involves the disruption of the upstream PmrAB and PhoPQ two-component system (TCS) control caused by mutations in the regulatory genes. Interestingly, previous studies have yielded conflicting results regarding the interaction of regulatory genes related to colistin resistance in Escherichia coli, specifically those surrounding PhoPQ and PmrAB TCS. RESULTS In our study, we focused on two clinical non-mcr colistin-resistant strains of E. coli, TSAREC02 and TSAREC03, to gain a better understanding of their resistance mechanisms. Upon analysis, we discovered that TSAREC02 had a deletion (Δ27-45) in MgrB, as well as substitutions (G206R, Y222H) in PmrB. On the other hand, TSAREC03 exhibited a long deletion (Δ84-224) in PhoP, along with substitutions (M1I, L14P, P178S, T235N) in PmrB. We employed recombinant DNA techniques to explore the interaction between the PhoPQ and PmrAB two-component systems (TCSs) and examine the impact of the mutated phoPQ and pmrB genes on the minimum inhibitory concentrations (MICs) of colistin. We observed significant changes in the expression of the pmrD gene, which encodes a connector protein regulated by the PhoPQ TCS, in the TSAREC02 wild-type (WT)-mgrB replacement mutant and the TSAREC03 WT-phoP replacement mutant, compared to their respective parental strains. However, the expressions of pmrB/pmrA, which reflect PmrAB TCS activity, and the colistin MICs remained unchanged. In contrast, the colistin MICs and pmrB/pmrA expression levels were significantly reduced in the pmrB deletion mutants from both TSAREC02 and TSAREC03, compared to their parental strains. Moreover, we were able to restore colistin resistance and the expressions of pmrB/pmrA by transforming a plasmid containing the parental mutated pmrB back into the TSAREC02 and TSAREC03 mutants, respectively. CONCLUSION While additional data from clinical E. coli isolates are necessary to validate whether our findings could be broadly applied to the E. coli population, our study illuminates distinct regulatory pathway interactions involving colistin resistance in E. coli compared to other species of Enterobacterales. The added information provided by our study contribute to a deeper understanding of the complex pathway interactions within Enterobacterales.
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Affiliation(s)
- Ching-Hsun Wang
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, No. 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan
| | - L Kristopher Siu
- Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli, Taiwan
| | - Feng-Yee Chang
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, No. 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan
| | - Yu-Kuo Tsai
- Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli, Taiwan
| | - Li-Yueh Huang
- Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Miaoli, Taiwan
| | - Jung-Chung Lin
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, No. 325, Section 2, Cheng-Kung Road, Neihu 114, Taipei, Taiwan.
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Barretto LAF, Van PKT, Fowler CC. Conserved patterns of sequence diversification provide insight into the evolution of two-component systems in Enterobacteriaceae. Microb Genom 2024; 10:001215. [PMID: 38502064 PMCID: PMC11004495 DOI: 10.1099/mgen.0.001215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/29/2024] [Indexed: 03/20/2024] Open
Abstract
Two-component regulatory systems (TCSs) are a major mechanism used by bacteria to sense and respond to their environments. Many of the same TCSs are used by biologically diverse organisms with different regulatory needs, suggesting that the functions of TCS must evolve. To explore this topic, we analysed the amino acid sequence divergence patterns of a large set of broadly conserved TCS across different branches of Enterobacteriaceae, a family of Gram-negative bacteria that includes biomedically important genera such as Salmonella, Escherichia, Klebsiella and others. Our analysis revealed trends in how TCS sequences change across different proteins or functional domains of the TCS, and across different lineages. Based on these trends, we identified individual TCS that exhibit atypical evolutionary patterns. We observed that the relative extent to which the sequence of a given TCS varies across different lineages is generally well conserved, unveiling a hierarchy of TCS sequence conservation with EnvZ/OmpR as the most conserved TCS. We provide evidence that, for the most divergent of the TCS analysed, PmrA/PmrB, different alleles were horizontally acquired by different branches of this family, and that different PmrA/PmrB sequence variants have highly divergent signal-sensing domains. Collectively, this study sheds light on how TCS evolve, and serves as a compendium for how the sequences of the TCS in this family have diverged over the course of evolution.
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Affiliation(s)
- Luke A. F. Barretto
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G2E9, Canada
| | - Patryc-Khang T. Van
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G2E9, Canada
| | - Casey C. Fowler
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G2E9, Canada
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Basu S, Veeraraghavan B, Anbarasu A. Impact of PmrB mutations on clinical Klebsiella pneumoniae with variable colistin-susceptibilities: Structural insights and potent therapeutic solutions. Chem Biol Drug Des 2024; 103:e14381. [PMID: 37875387 DOI: 10.1111/cbdd.14381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/09/2023] [Accepted: 10/10/2023] [Indexed: 10/26/2023]
Abstract
Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections continue to impose high morbidity threats to hospitalized patients worldwide, limiting therapeutic options to last-resort antibiotics like colistin. However, the dynamic genomic landscape of colistin-resistant K. pneumoniae (COLR-Kp) invoked ardent exploration of underlying molecular signatures for therapeutic propositions/designs. We unveiled the structural impact of the widespread and emerging PmrB mutations involved in colistin resistance (COLR) in K. pneumoniae. In the present study, clinical isolates of K. pneumoniae expressed variable susceptibilities to colistin (>0.5 μg/mL for resistant and ≤0.25 μg/mL for susceptible) despite mutations such as T157P, G207D and T246A. The protein sequences extracted from in-house sequenced genomes were used to model mutant PmrB proteins and analyze the underlying structural alterations. The mutations were contrasted based on molecular dynamics simulation trajectories, free-energy landscapes and structural flexibility profiles. The altered backbone flexibilities can be an essential factor for mutant selection by COLR K. pneumoniae and can provide clues to deal with emerging mutants. Furthermore, PmrB having high druggability confidence (>0.99), was explored as a potential target for 1396 virtually screened FDA-approved drug candidates. Among the top-10 compounds (scores >70), amphotericin B was found to be potential candidate with high affinity (Binding energy <-8 kcal/mol) and stable interactions (RMSF <0.7 Å) against PmrB druggable pockets, despite the mutations, which encourages future adjunct therapeutic research against COLR-Kp.
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Affiliation(s)
- Soumya Basu
- Medical and Biological Computing Laboratory, School of Biosciences and Technology (SBST), Vellore Institute of Technology (VIT), Vellore, India
| | - Balaji Veeraraghavan
- Department of Clinical Microbiology, Christian Medical College (CMC), Vellore, India
| | - Anand Anbarasu
- Medical and Biological Computing Laboratory, School of Biosciences and Technology (SBST), Vellore Institute of Technology (VIT), Vellore, India
- Department of Biotechnology, SBST, VIT, Vellore, India
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Lou YC, Huang HY, Yeh HH, Chiang WH, Chen C, Wu KP. Structural basis of transcriptional activation by the OmpR/PhoB-family response regulator PmrA. Nucleic Acids Res 2023; 51:10049-10058. [PMID: 37665001 PMCID: PMC10570014 DOI: 10.1093/nar/gkad724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/09/2023] [Accepted: 08/21/2023] [Indexed: 09/05/2023] Open
Abstract
PmrA, an OmpR/PhoB-family response regulator, triggers gene transcription responsible for polymyxin resistance in bacteria by recognizing promoters where the canonical-35 element is replaced by the pmra-box, representing the PmrA recognition sequence. Here, we report a cryo-electron microscopy (cryo-EM) structure of a bacterial PmrA-dependent transcription activation complex (TAC) containing a PmrA dimer, an RNA polymerase σ70 holoenzyme (RNAPH) and the pbgP promoter DNA. Our structure reveals that the RNAPH mainly contacts the PmrA C-terminal DNA-binding domain (DBD) via electrostatic interactions and reorients the DBD three base pairs upstream of the pmra-box, resulting in a dynamic TAC conformation. In vivo assays show that the substitution of the DNA-recognition residue eliminated its transcriptional activity, while variants with altered RNAPH-interacting residues resulted in enhanced transcriptional activity. Our findings suggest that both PmrA recognition-induced DNA distortion and PmrA promoter escape play crucial roles in its transcriptional activation.
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Affiliation(s)
- Yuan-Chao Lou
- Biomedical Translation Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Hsuan-Yu Huang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Hsin-Hong Yeh
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Wei-Hung Chiang
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Chinpan Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Kuen-Phon Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
- Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei 10617, Taiwan
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Zhu L, Li P, Zhang G, He Z, Tao X, Ji Y, Yang W, Zhu X, Luo W, Liao W, Chen C, Liu Y, Zhang W. Role of the ISKpn element in mediating mgrB gene mutations in ST11 hypervirulent colistin-resistant Klebsiella pneumoniae. Front Microbiol 2023; 14:1277320. [PMID: 37840706 PMCID: PMC10569121 DOI: 10.3389/fmicb.2023.1277320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/11/2023] [Indexed: 10/17/2023] Open
Abstract
Background Colistin has emerged as a last-resort therapeutic against antibiotic-resistant bacterial infections, particularly those attributed to carbapenem-resistant Enterobacteriaceae (CRE) like CRKP. Yet, alarmingly, approximately 45% of multidrug-resistant Klebsiella pneumoniae strains now manifest resistance to colistin. Through our study, we discerned that the synergy between carbapenemase and IS elements amplifies resistance in Klebsiella pneumoniae, thereby narrowing the existing therapeutic avenues. This underscores the instrumental role of IS elements in enhancing colistin resistance through mgrB disruption. Methods From 2021 to 2023, 127 colistin-resistant Klebsiella pneumoniae isolates underwent meticulous examination. We embarked on an exhaustive genetic probe, targeting genes associated with both plasmid-mediated mobile resistance-encompassing blaKPC, blaNDM, blaIMP, blaVIM, blaOXA-48-like, and mcr-1 to mcr-8-and chromosome-mediated resistance systems, including PhoP/Q, PmrA/B, and mgrB. PCR amplification revealed the presence of virulence-associated genes from the pLVPK plasmid, such as rmpA, rmpA2, iucA, iroB, and peg344. mgrB sequencing was delegated to Sangon Biotech, Shanghai, and the sequences procured were validated using BLAST. Our search for IS elements was navigated through the IS finder portal. Phenotypically, we harnessed broth microdilution (BMD) to ascertain the MICs of colistin. To sketch the clonal lineage of mgrB-mutated CoR-Kp isolates, sophisticated methodologies like MLST and PFGE were deployed. S1-PFGE unraveled the intrinsic plasmids in these isolates. Our battery of virulence assessment techniques ranged from the string test and capsular serotyping to the serum killing assay and the Galleria mellonella larval infection model. Results Among the 127 analyzed isolates, 20 showed an enlarged mgrB PCR amplicon compared to wild-type strains. These emerged over a three-year period: three in 2021, thirteen in 2022, and four in 2023. Antimicrobial susceptibility tests revealed that these isolates consistently resisted several drugs, notably TCC, TZP, CAZ, and COL. Additionally, 85% resisted both DOX and TOB. The MICs for colistin across these strains ranged between 16 to 64 mg/L, with a median of 40 mg/L. From a genetic perspective, MLST unanimously categorized these mgrB-mutated CoR-hvKp isolates as ST11. PFGE further delineated them into six distinct clusters, with clusters A and D being predominant. This distribution suggests potential horizontal and clonal genetic transmission. Intriguingly, every mgrB-mutated CoR-hvKP isolate possessed at least two virulence genes akin to the pLVPK-like virulence plasmid, with iroB and rmpA2 standing out. Their virulence was empirically validated both in vitro and in vivo. A pivotal discovery was the identification of three distinct insertion sequence (IS) elements within or near the mgrB gene. These were:ISKpn26 in eleven isolates, mainly in cluster A, with various insertion sites including +74, +125, and an upstream -35.ISKpn14 in four isolates with insertions at +93, -35, and two upstream at -60.IS903B present in five isolates, marking positions like +74, +125, +116, and -35 in the promoter region. These diverse insertions, spanning six unique locations in or near the mgrB gene, underscore its remarkable adaptability. Conclusion Our exploration spotlights the ISKpn element's paramount role in fostering mgrB gene mutations in ST11 hypervirulent colistin-resistant Klebsiella pneumoniae. Employing MLST and PFGE, we unearthed two primary genetic conduits: clonal and horizontal. A striking observation was the ubiquitous presence of the KPC carbapenemase gene in all the evaluated ST11 hypervirulent colistin-resistant Klebsiella pneumoniae strains, with a majority also harboring the NDM gene. The myriad mgrB gene insertion locales accentuate its flexibility and the overarching influence of IS elements, notably the pervasive IS5-like variants ISKpn26 and IS903B. Our revelations illuminate the escalating role of IS elements in antibiotic resistance within ST11 hypervirulent colistin-resistant Klebsiella pneumoniae, advocating for innovative interventions to counteract these burgeoning resistance paradigms given their profound ramifications for prevailing treatment modalities.
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Affiliation(s)
- Lanlan Zhu
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
| | - Ping Li
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
- Jiangxi Institute of Respiratory Disease, The First Affiliated Hospital of Nanchang University, Nanchang, China
- Yichun People’s Hospital, Yichun, China
| | - Guangyi Zhang
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
| | - Zhiyong He
- First Clinical Medical College of Nanchang University, Nanchang University, Nanchang, China
| | - Xingyu Tao
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
- Jiangxi Institute of Respiratory Disease, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yicheng Ji
- Department of Hospital Infection Control, First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
| | - Wenjing Yang
- Department of Hospital Infection Control, First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
| | - Xiaofang Zhu
- Department of Hospital Infection Control, First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
| | - Wanying Luo
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
- Jiangxi Institute of Respiratory Disease, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Wenjian Liao
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
| | - Chuanhui Chen
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
| | - Yang Liu
- National Regional Center for Respiratory Medicine, Jiang Xi Hospital of China-Japan Friendship Hospital, Nanchang, China
- Department of Clinical Microbiology, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
| | - Wei Zhang
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Nanchang University, Nanchang University, Nanchang, China
- Jiangxi Institute of Respiratory Disease, The First Affiliated Hospital of Nanchang University, Nanchang, China
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Thai VC, Stubbs KA, Sarkar-Tyson M, Kahler CM. Phosphoethanolamine Transferases as Drug Discovery Targets for Therapeutic Treatment of Multi-Drug Resistant Pathogenic Gram-Negative Bacteria. Antibiotics (Basel) 2023; 12:1382. [PMID: 37760679 PMCID: PMC10525099 DOI: 10.3390/antibiotics12091382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 08/25/2023] [Accepted: 08/26/2023] [Indexed: 09/29/2023] Open
Abstract
Antibiotic resistance caused by multidrug-resistant (MDR) bacteria is a major challenge to global public health. Polymyxins are increasingly being used as last-in-line antibiotics to treat MDR Gram-negative bacterial infections, but resistance development renders them ineffective for empirical therapy. The main mechanism that bacteria use to defend against polymyxins is to modify the lipid A headgroups of the outer membrane by adding phosphoethanolamine (PEA) moieties. In addition to lipid A modifying PEA transferases, Gram-negative bacteria possess PEA transferases that decorate proteins and glycans. This review provides a comprehensive overview of the function, structure, and mechanism of action of PEA transferases identified in pathogenic Gram-negative bacteria. It also summarizes the current drug development progress targeting this enzyme family, which could reverse antibiotic resistance to polymyxins to restore their utility in empiric therapy.
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Affiliation(s)
- Van C. Thai
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (V.C.T.); (M.S.-T.)
| | - Keith A. Stubbs
- School of Molecular Sciences, University of Western Australia, Crawley, WA 6009, Australia;
| | - Mitali Sarkar-Tyson
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (V.C.T.); (M.S.-T.)
| | - Charlene M. Kahler
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (V.C.T.); (M.S.-T.)
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Lu J, Han M, Yu HH, Bergen PJ, Liu Y, Zhao J, Wickremasinghe H, Jiang X, Hu Y, Du H, Zhu Y, Velkov T. Lipid A Modification and Metabolic Adaptation in Polymyxin-Resistant, New Delhi Metallo-β-Lactamase-Producing Klebsiella pneumoniae. Microbiol Spectr 2023; 11:e0085223. [PMID: 37432123 PMCID: PMC10433984 DOI: 10.1128/spectrum.00852-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/12/2023] [Indexed: 07/12/2023] Open
Abstract
Polymyxins are last-line antibiotics employed against multidrug-resistant (MDR) Klebsiella pneumoniae. Worryingly, polymyxin resistance is rapidly on the rise globally. Polymyxins initially target lipid A of lipopolysaccharides (LPSs) in the cell outer membrane (OM), causing disorganization and cell lysis. While most studies focus on how genetic variations confer polymyxin resistance, the mechanisms of membrane remodeling and metabolic changes in polymyxin-resistant strains remain unclear, thus hampering the development of effective therapies to treat severe K. pneumoniae infections. In the present study, lipid A profiling, OM lipidomics, genomics, and metabolomics were integrated to elucidate the global mechanisms of polymyxin resistance and metabolic adaptation in a polymyxin-resistant strain (strain S01R; MIC of >128 mg/L) obtained from K. pneumoniae strain S01, a polymyxin-susceptible (MIC of 2 mg/L), New Delhi metallo-β-lactamase (NDM)-producing MDR clinical isolate. Genomic analysis revealed a novel in-frame deletion at position V258 of PhoQ in S01R, potentially leading to lipid A modification with 4-amino-4-deoxy-l-arabinose (L-Ara4N) despite the absence of polymyxin B. Comparative metabolomic analysis revealed slightly elevated levels of energy production and amino acid metabolism in S01R compared to their levels in S01. Exposure to polymyxin B (4 mg/L for S01 and 512 mg/L for S01R) substantially altered energy, nucleotide, and amino acid metabolism and resulted in greater accumulation of lipids in both strains. Furthermore, the change induced by polymyxin B treatment was dramatic at both 1 and 4 h in S01 but only significant at 4 h in S01R. Overall, profound metabolic adaptation was observed in S01R following polymyxin B treatment. These findings contribute to our understanding of polymyxin resistance mechanisms in problematic NDM-producing K. pneumoniae strains and may facilitate the discovery of novel therapeutic targets. IMPORTANCE Antimicrobial resistance (AMR) is a major threat to global health. The emergence of resistance to the polymyxins that are the last line of defense in so-called Gram-negative "superbugs" has further increased the urgency to develop novel therapies. There are frequent outbreaks of K. pneumoniae infections in hospitals being reported, and polymyxin usage is increasing remarkably. Importantly, the polymyxin-resistant K. pneumoniae strains are imposing more severe consequences to health systems. Using metabolomics, lipid A profiling, and outer membrane lipidomics, our findings reveal (i) changes in the pentose phosphate pathway and amino acid and nucleotide metabolism in a susceptible strain following polymyxin treatment and (ii) how cellular metabolism, lipid A modification, and outer membrane remodeling were altered in K. pneumoniae following the acquisition of polymyxin resistance. Our study provides, for the first time, mechanistic insights into metabolic responses to polymyxin treatment in a multidrug-resistant, NDM-producing K. pneumoniae clinical isolate with acquired polymyxin resistance. Overall, these results will assist in identifying new therapeutic targets to combat and prevent polymyxin resistance.
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Affiliation(s)
- Jing Lu
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Meiling Han
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Heidi H. Yu
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Phillip J. Bergen
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Yiyun Liu
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Jinxin Zhao
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Hasini Wickremasinghe
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Xukai Jiang
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Yang Hu
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Haiyan Du
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Yan Zhu
- Infection Program, Department of Microbiology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Tony Velkov
- Department of Pharmacology, The Faculty of Medicine Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
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Li L, Ma J, Cheng P, Li M, Yu Z, Song X, Yu Z, Sun H, Zhang W, Wang Z. Roles of two-component regulatory systems in Klebsiella pneumoniae: Regulation of virulence, antibiotic resistance, and stress responses. Microbiol Res 2023; 272:127374. [PMID: 37031567 DOI: 10.1016/j.micres.2023.127374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 04/04/2023] [Accepted: 04/04/2023] [Indexed: 04/09/2023]
Abstract
Klebsiella pneumoniae is an opportunistic pathogen belonging to the Enterobacteriaceae family, which is the leading cause of nosocomial infections. The emergence of hypervirulent and multi-drug resistant K. pneumoniae is a serious health threat. In the process of infection, K. pneumoniae needs to adapt to different environmental conditions, and the two-component regulatory system (TCS) composed of a sensor histidine kinase and response regulator is an important bacterial regulatory system in response to external stimuli. Understanding how K. pneumoniae perceives and responds to complex environmental stimuli provides insights into TCS regulation mechanisms and new targets for drug design. In this review, we analyzed the TCS composition and summarized the regulation mechanisms of TCSs, focusing on the regulation of genes involved in virulence, antibiotic resistance, and stress response. Collectively, these studies demonstrated that several TCSs play important roles in the regulation of virulence, antibiotic resistance and stress responses of K. pneumoniae. A single two-component regulatory system can participate in the regulation of several stress responses, and one stress response process may include several TCSs, forming a complex regulatory network. However, the function and regulation mechanism of some TCSs require further study. Hence, future research endeavors are required to enhance the understanding of TCS regulatory mechanisms and networks in K. pneumoniae, which is essential for the design of novel drugs targeting TCSs.
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Wang L, Huang X, Jin Q, Tang J, Zhang H, Zhang JR, Wu H. Two-Component Response Regulator OmpR Regulates Mucoviscosity through Energy Metabolism in Klebsiella pneumoniae. Microbiol Spectr 2023; 11:e0054423. [PMID: 37097167 PMCID: PMC10269446 DOI: 10.1128/spectrum.00544-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 04/02/2023] [Indexed: 04/26/2023] Open
Abstract
Hypermucoviscosity is a hallmark of hypervirulent Klebsiella pneumoniae (hvKP). However, the molecular basis of its regulation is largely unknown. We hypothesize that hypermucoviscosity is modulated via two-component signal transduction systems (TCSs). In-frame deletion mutants of all 33 response regulators of hvKP ATCC43816 were generated using CRISPR/CAS and evaluated for their impacts on hypermucoviscosity. The response regulator OmpR is required for hypermucoviscosity in vitro and virulence in vivo in a mouse pneumonia model. The ΔompR mutant lost its mucoidy but retained its capsule level and comparable rmpADC expression, so transcriptomic analysis by RNA-Seq was performed to identify differentially expressed genes (DEGs) in ΔompR mutant. The top 20 Gene Ontology terms of 273 DEGs belong to purine ribonucleotide triphosphate biosynthetic and metabolic process, transmembrane transport, and amino acid metabolism. Among the overexpressed genes in the ΔompR mutant, the atp operon encoding F-type ATP synthase and the gcvTHP encoding glycine cleavage system were characterized further as overexpression of either operon reduced the mucoviscosity and increased the production of ATP. Furthermore, OmpR directly bound the promoter region of the atp operon, not the gcvTHP, suggesting that OmpR regulates the expression of the atp operon directly and gcvTHP indirectly. Hence, the loss of OmpR led to the overexpression of F-type ATP synthase and glycine cleavage system, which altered the energetic status of ΔompR cells and contributed to the subsequent reduction in the mucoviscosity. Our study has uncovered a previously unknown regulation of bacterial metabolism by OmpR and its influence on hypermucoviscosity. IMPORTANCE Hypermucoviscosity is a critical virulent factor for Klebsiella pneumoniae infections, and its regulation remains poorly understood at the molecular level. This study aims to address this knowledge gap by investigating the role of response regulators in mediating hypermucoviscosity in K. pneumoniae. We screened 33 response regulators and found that OmpR is essential for hypermucoviscosity and virulence of K. pneumoniae in a mouse pneumonia model. Transcriptomic analysis uncovered that genes involved in energy production and metabolism are highly upregulated in the ΔompR mutant, suggesting a potential link between bacterial energy status and hypermucoviscosity. Overexpression of those genes increased production of ATP and reduced mucoviscosity, recapitulating the ΔompR mutant phenotype. Our findings provide new insights into the regulation of K. pneumoniae hypermucoviscosity by a two-component signal transduction system, highlighting the previously unknown role of OmpR in regulating bacterial energy status and its influence on hypermucoviscosity.
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Affiliation(s)
- Lijun Wang
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
- Department of Laboratory Medicine, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
| | - Xueting Huang
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
| | - Qian Jin
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
| | - Jie Tang
- Department of Laboratory Medicine, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
| | - Hua Zhang
- Department of Integrative Biomedical and Diagnostic Sciences, Oregon Health and Science University School of Dentistry, Portland, Oregon, USA
| | - Jing-Ren Zhang
- Center for Infectious Disease Research, Department of Basic Medical Science, School of Medicine, Tsinghua University, Beijing, China
- Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing, China
| | - Hui Wu
- Department of Integrative Biomedical and Diagnostic Sciences, Oregon Health and Science University School of Dentistry, Portland, Oregon, USA
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11
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De Gaetano GV, Lentini G, Famà A, Coppolino F, Beninati C. Antimicrobial Resistance: Two-Component Regulatory Systems and Multidrug Efflux Pumps. Antibiotics (Basel) 2023; 12:965. [PMID: 37370284 DOI: 10.3390/antibiotics12060965] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/22/2023] [Accepted: 05/24/2023] [Indexed: 06/29/2023] Open
Abstract
The number of multidrug-resistant bacteria is rapidly spreading worldwide. Among the various mechanisms determining resistance to antimicrobial agents, multidrug efflux pumps play a noteworthy role because they export extraneous and noxious substrates from the inside to the outside environment of the bacterial cell contributing to multidrug resistance (MDR) and, consequently, to the failure of anti-infective therapies. The expression of multidrug efflux pumps can be under the control of transcriptional regulators and two-component systems (TCS). TCS are a major mechanism by which microorganisms sense and reply to external and/or intramembrane stimuli by coordinating the expression of genes involved not only in pathogenic pathways but also in antibiotic resistance. In this review, we describe the influence of TCS on multidrug efflux pump expression and activity in some Gram-negative and Gram-positive bacteria. Taking into account the strict correlation between TCS and multidrug efflux pumps, the development of drugs targeting TCS, alone or together with already discovered efflux pump inhibitors, may represent a beneficial strategy to contribute to the fight against growing antibiotic resistance.
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Affiliation(s)
| | - Germana Lentini
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
| | - Agata Famà
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
| | - Francesco Coppolino
- Department of Biomedical, Dental and Imaging Sciences, University of Messina, 98124 Messina, Italy
| | - Concetta Beninati
- Department of Human Pathology, University of Messina, 98124 Messina, Italy
- Scylla Biotech Srl, 98124 Messina, Italy
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12
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Ko SY, Kim N, Park SY, Kim SY, Shin M, Lee JC. Acinetobacter baumannii under Acidic Conditions Induces Colistin Resistance through PmrAB Activation and Lipid A Modification. Antibiotics (Basel) 2023; 12:antibiotics12050813. [PMID: 37237716 DOI: 10.3390/antibiotics12050813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/24/2023] [Accepted: 04/24/2023] [Indexed: 05/28/2023] Open
Abstract
Colistin is a last-resort antimicrobial agent for treating carbapenem-resistant Acinetobacter baumannii infections. The activation of PmrAB by several environmental signals induces colistin resistance in Gram-negative bacteria. This study investigated the molecular mechanisms of colistin resistance in A. baumannii under acidic conditions using wild-type (WT) A. baumannii 17978, ΔpmrA and ΔpmrB mutants, and pmrA-complemented strains. The pmrA or pmrB deletion did not affect the growth of A. baumannii under acidic or aerobic conditions. A. baumannii under acidic (pH 5.5) and high-iron (1 mM) conditions showed 32- and 8-fold increases in the minimum inhibitory concentrations (MICs) of colistin, respectively. The ΔpmrA and ΔpmrB mutants at pH 5.5 showed a significant decrease in colistin MICs compared to the WT strain at pH 5.5. No difference in colistin MICs was observed between WT and mutant strains under high-iron conditions. The pmrCAB expression significantly increased in the WT strain at pH 5.5 compared to the WT strain at pH 7.0. The pmrC expression significantly decreased in two mutant strains at pH 5.5 compared to the WT strain at pH 5.5. The PmrA protein was expressed in the ΔpmrA strain carrying ppmrA_FLAG plasmids at pH 5.5 but not at pH 7.0. Lipid A modification by the addition of phosphoethanolamine was observed in the WT strain at pH 5.5. In conclusion, this study demonstrated that A. baumannii under acidic conditions induces colistin resistance via the activation of pmrCAB operon and subsequent lipid A modification.
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Affiliation(s)
- Seo-Yeon Ko
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea
| | - Nayeong Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea
| | - Seong-Yong Park
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea
| | - Seong-Yeop Kim
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea
| | - Minsang Shin
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea
| | - Je-Chul Lee
- Department of Microbiology, School of Medicine, Kyungpook National University, Daegu 41944, Republic of Korea
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13
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Baran A, Kwiatkowska A, Potocki L. Antibiotics and Bacterial Resistance-A Short Story of an Endless Arms Race. Int J Mol Sci 2023; 24:ijms24065777. [PMID: 36982857 PMCID: PMC10056106 DOI: 10.3390/ijms24065777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 03/10/2023] [Accepted: 03/15/2023] [Indexed: 03/30/2023] Open
Abstract
Despite the undisputed development of medicine, antibiotics still serve as first-choice drugs for patients with infectious disorders. The widespread use of antibiotics results from a wide spectrum of their actions encompassing mechanisms responsible for: the inhibition of bacterial cell wall biosynthesis, the disruption of cell membrane integrity, the suppression of nucleic acids and/or proteins synthesis, as well as disturbances of metabolic processes. However, the widespread availability of antibiotics, accompanied by their overprescription, acts as a double-edged sword, since the overuse and/or misuse of antibiotics leads to a growing number of multidrug-resistant microbes. This, in turn, has recently emerged as a global public health challenge facing both clinicians and their patients. In addition to intrinsic resistance, bacteria can acquire resistance to particular antimicrobial agents through the transfer of genetic material conferring resistance. Amongst the most common bacterial resistance strategies are: drug target site changes, increased cell wall permeability to antibiotics, antibiotic inactivation, and efflux pumps. A better understanding of the interplay between the mechanisms of antibiotic actions and bacterial defense strategies against particular antimicrobial agents is crucial for developing new drugs or drug combinations. Herein, we provide a brief overview of the current nanomedicine-based strategies that aim to improve the efficacy of antibiotics.
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Affiliation(s)
- Aleksandra Baran
- Department of Biotechnology, College of Natural Sciences, University of Rzeszów, Pigonia 1, 35-310 Rzeszow, Poland
| | - Aleksandra Kwiatkowska
- Institute of Physical Culture Studies, College of Medical Sciences, University of Rzeszów, ul. Towarnickiego 3, 35-959 Rzeszów, Poland
| | - Leszek Potocki
- Department of Biotechnology, College of Natural Sciences, University of Rzeszów, Pigonia 1, 35-310 Rzeszow, Poland
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14
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Li S, Feng X, Li M, Shen Z. In vivo adaptive antimicrobial resistance in Klebsiella pneumoniae during antibiotic therapy. Front Microbiol 2023; 14:1159912. [PMID: 37007508 PMCID: PMC10061107 DOI: 10.3389/fmicb.2023.1159912] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 02/27/2023] [Indexed: 03/18/2023] Open
Abstract
Klebsiella pneumoniae is one of the leading pathogens contributing to antimicrobial resistance. The emergence of carbapenem-resistant K. pneumoniae (CRKP) has put the use of clinical antimicrobial agents in a dilemma. In particular, CRKP exhibiting resistance to ceftazidime/avibactam, tigecycline and colistin have raised great clinical concern, as these are the last-resort antibiotics for the treatment of CRKP infections. Within-host evolution is a survival strategy closely related to the emergence of antimicrobial resistance, while little attention has been paid to the in vivo genetic process of conversion from antibiotic-susceptible to resistant K. pneumoniae. Here we have a literature review regarding the in vivo evolution of resistance to carbapenems, ceftazidime/avibactam, tigecycline, and colistin in K. pneumoniae during antibacterial therapy, and summarized the detailed resistance mechanisms. In general, acquiring blaKPC and blaNDM harboring-plasmid, specific mutations in blaKPC, and porin genes, such as ompK35 and ompK36, upregulation of blaKPC, contribute to the development of carbapenem and ceftazidime/avibactam resistance in vivo. Overexpression of efflux pumps, acquiring plasmid-carrying tet (A) variants, and ribosomal protein change can lead to the adaptive evolution of tigecycline resistance. Specific mutations in chromosomes result in the cationic substitution of the phosphate groups of lipid A, thus contributing to colistin resistance. The resistant plasmid might be acquired from the co-infecting or co-colonizing strains, and the internal environment and antibiotic selection pressure contribute to the emergence of resistant mutants. The internal environment within the human host could serve as an important source of resistant K. pneumoniae strains.
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Affiliation(s)
- Shuangshuang Li
- Department of Laboratory Medicine, Ningbo Hospital, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Ningbo, China
| | - Xudong Feng
- State Key Laboratory for the Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Min Li
- Department of Laboratory Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- *Correspondence: Min Li,
| | - Zhen Shen
- Department of Laboratory Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Zhen Shen,
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15
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Kuo CH, Lin WF, Liu CJ, Wang ZC, Liu TY, Peng HL. Role of the stress-responsive two-component system CpxAR in regulating fimbriae expression in Klebsiella pneumoniae CG43. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2023:S1684-1182(23)00040-3. [PMID: 36898943 DOI: 10.1016/j.jmii.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 02/06/2023] [Accepted: 02/18/2023] [Indexed: 02/27/2023]
Abstract
BACKGROUND CpxAR is a two-component system that allows bacteria to reorganize envelope structures in response to extracellular stimuli. CpxAR negatively affects type 1 fimbriae expression in Klebsiella pneumoniae CG43, a hypervirulent strain. The involvement of CpxAR in the regulation of type 3 fimbriae expression was investigated. METHODS cpxAR, cpxA, and cpxR gene-specific deletion mutants were generated. The deletion effects on the expression of type 1 and type 3 fimbriae were analyzed via measuring the promoter activity, mannose sensitive yeast agglutination activity, biofilm formation, and the production of the major pilins FimA and MrkA respectively. RNA sequencing analysis of CG43S3, ΔcpxAR, ΔcpxR and Δfur was employed to study the regulatory mechanism influencing the expression of type 3 fimbriae. RESULTS Deletion of cpxAR increased type 1 and type 3 fimbrial expression. Comparative transcriptomic analysis showed that the expression of oxidative stress-responsive enzymes, type 1 and type 3 fimbriae, and iron acquisition and homeostasis control systems were differentially affected by cpxAR or cpxR deletion. Subsequent analysis revealed that the small RNA RyhB negatively affects the expression of type 3 fimbriae, while CpxAR positively controls ryhB expression. Finally, the site-directed mutation of the predicted interacting sequences of RyhB with the mRNA of MrkA attenuated the RyhB repression of type 3 fimbriae. CONCLUSION CpxAR negatively regulates the expression of type 3 fimbriae by modulating cellular iron levels thereafter activating the expression of RyhB. The activated RyhB represses the expression of type 3 fimbriae by base-pairing binding to the 5'region of mrkA mRNA.
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Affiliation(s)
- Chih-Hao Kuo
- Department of Biological Science and Technology, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Wei-Feng Lin
- Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Chia-Jui Liu
- Department of Biological Science and Technology, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Zhe-Chong Wang
- Department of Biological Science and Technology, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Ting-Yi Liu
- Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Hwei-Ling Peng
- Department of Biological Science and Technology, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan; Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan.
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16
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Li H, Mattingly AE, Smith RD, Melander RJ, Ernst RK, Melander C. 6-Bromoindirubin-3'-oxime derivatives are highly active colistin adjuvants against Klebsiella pneumoniae. RSC Med Chem 2023; 14:247-252. [PMID: 36846374 PMCID: PMC9945867 DOI: 10.1039/d2md00370h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 11/25/2022] [Indexed: 12/03/2022] Open
Abstract
Multidrug resistant (MDR) bacterial infections have become increasingly common, leading clinicians to rely on last-resort antibiotics such as colistin. However, the utility of colistin is becoming increasingly compromised as a result of increasing polymyxin resistance. Recently we discovered that derivatives of the eukaryotic kinase inhibitor meridianin D abrogate colistin resistance in several Gram-negative species. A subsequent screen of three commercial kinase inhibitor libraries led to the identification of several scaffolds that potentiate colistin activity, including 6-bromoindirubin-3'-oxime, which potently suppresses colistin resistance in Klebsiella pneumoniae. Herein we report the activity of a library of 6-bromoindirubin-3'-oxime analogs and identify four derivatives that show equal or increased colistin potentiation activity compared to the parent compound.
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Affiliation(s)
- Haoting Li
- Department of Chemistry and Biochemistry, University of Notre Dame Notre Dame Indiana 46556 USA
| | - Anne E Mattingly
- Department of Chemistry and Biochemistry, University of Notre Dame Notre Dame Indiana 46556 USA
| | - Richard D Smith
- Department of Microbial Pathogenesis, University of Maryland Baltimore Maryland USA
| | - Roberta J Melander
- Department of Chemistry and Biochemistry, University of Notre Dame Notre Dame Indiana 46556 USA
| | - Robert K Ernst
- Department of Microbial Pathogenesis, University of Maryland Baltimore Maryland USA
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame Notre Dame Indiana 46556 USA
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17
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Hussein M, Jasim R, Gocol H, Baker M, Thombare VJ, Ziogas J, Purohit A, Rao GG, Li J, Velkov T. Comparative Proteomics of Outer Membrane Vesicles from Polymyxin-Susceptible and Extremely Drug-Resistant Klebsiella pneumoniae. mSphere 2023; 8:e0053722. [PMID: 36622250 PMCID: PMC9942579 DOI: 10.1128/msphere.00537-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 12/06/2022] [Indexed: 01/10/2023] Open
Abstract
Outer membrane vesicles (OMVs) secreted by Gram-negative bacteria serve as transporters for the delivery of cargo such as virulence and antibiotic resistance factors. OMVs play a key role in the defense against membrane-targeting antibiotics such as the polymyxin B. Herein, we conducted comparative proteomics of OMVs from paired Klebsiella pneumoniae ATCC 700721 polymyxin-susceptible (polymyxin B MIC = 0.5 mg/L) and an extremely resistant (polymyxin B MIC ≥128 mg/L), following exposure to 2 mg/L of polymyxin B. Comparative profiling of the OMV subproteome of each strain revealed proteins from multiple perturbed pathways, particularly in the polymyxin-susceptible strain, including outer membrane assembly (lipopolysaccharide, O-antigen, and peptidoglycan biosynthesis), cationic antimicrobial peptide resistance, β-lactam resistance, and quorum sensing. In the polymyxin-susceptible strain, polymyxin B treatment reduced the expression of OMV proteins in the pathways related to adhesion, virulence, and the cell envelope stress responses, whereas, in the polymyxin-resistant strain, the proteins involved in LPS biosynthesis, RNA degradation, and nucleotide excision repair were significantly overexpressed in response to polymyxin B treatment. Intriguingly, the key polymyxin resistance enzymes 4-amino-4-deoxy-l-arabinose transferase and the PhoPQ two-component protein kinase were significantly downregulated in the OMVs of the polymyxin-susceptible strain. Additionally, a significant reduction in class A β-lactamase proteins was observed following polymyxin B treatment in the OMVs of both strains, particularly the OMVs of the polymyxin-susceptible strain. These findings shed new light on the OMV subproteome of extremely polymyxin resistant K. pneumoniae, which putatively may serve as active decoys to make the outer membrane more impervious to polymyxin attack. IMPORTANCE OMVs can help bacteria to fight antibiotics not only by spreading antibiotic resistance genes but also by acting as protective armor against antibiotics. By employing proteomics, we found that OMVs have a potential role in shielding K. pneumoniae and acting as decoys to polymyxin attack, through declining the export of proteins (e.g., 4-amino-4-deoxy-l-arabinose transferase) involved in polymyxin resistance. Furthermore, polymyxin B treatment of both strains leads to shedding of the OMVs with perturbed proteins involved in outer membrane remodeling (e.g., LPS biosynthesis) as well as pathogenic potential of K. pneumoniae (e.g., quorum sensing). The problematic extended spectrum beta-lactamases SHV and TEM were significantly reduced in both strains, suggesting that polymyxin B may act as a potentiator to sensitize the bacterium to β-lactam antibiotics. This study highlights the importance of OMVs as "molecular mules" for the intercellular transmission and delivery of resistance and cellular repair factors in the bacterial response to polymyxins.
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Affiliation(s)
- Maytham Hussein
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Raad Jasim
- Department of Pharmacology, College of Pharmacy, University of Babylon, Iraq
| | - Hakan Gocol
- Department of Biochemistry and Pharmacology, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Mark Baker
- Discipline of Biological Sciences, Priority Research Centre in Reproductive Biology, Faculty of Science and IT, University of Newcastle, Callaghan, New South Wales, Australia
| | - Varsha J. Thombare
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - James Ziogas
- Department of Biochemistry and Pharmacology, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Aayush Purohit
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Gauri G. Rao
- Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Jian Li
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Tony Velkov
- Monash Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria, Australia
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18
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Zeczycki TN, Milton ME, Jung D, Thompson RJ, Jaimes FE, Hondros AD, Palethorpe S, Melander C, Cavanagh J. 2-Aminoimidazole Analogs Target PhoP Altering DNA Binding Activity and Affect Outer Membrane Stability in Gram-Negative Bacteria. Biochemistry 2022; 61:2948-2960. [DOI: 10.1021/acs.biochem.2c00560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Tonya N. Zeczycki
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Morgan E. Milton
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - David Jung
- Agile Sciences Inc., 617 Hutton Street, Raleigh, North Carolina27606, United States
| | - Richele J. Thompson
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Felicia E. Jaimes
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Alexander D. Hondros
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Samantha Palethorpe
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana46556, United States
| | - John Cavanagh
- Department of Biochemistry and Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, North Carolina27834, United States
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19
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Molecular Characteristics and Quantitative Proteomic Analysis of Klebsiella pneumoniae Strains with Carbapenem and Colistin Resistance. Antibiotics (Basel) 2022; 11:antibiotics11101341. [PMID: 36289999 PMCID: PMC9598126 DOI: 10.3390/antibiotics11101341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/27/2022] [Accepted: 09/29/2022] [Indexed: 12/05/2022] Open
Abstract
Carbapenem-resistant Klebsiella pneumoniae (CRKP) are usually multidrug resistant (MDR) and cause serious therapeutic problems. Colistin is a critical last-resort therapeutic option for MDR bacterial infections. However, increasing colistin use has led to the emergence of extensively drug-resistant (XDR) strains, raising a significant challenge for healthcare. In order to gain insight into the antibiotic resistance mechanisms of CRKP and identify potential drug targets, we compared the molecular characteristics and the proteomes among drug-sensitive (DS), MDR, and XDR K. pneumoniae strains. All drug-resistant isolates belonged to ST11, harboring blaKPC and hypervirulent genes. None of the plasmid-encoded mcr genes were detected in the colistin-resistant XDR strains. Through a tandem mass tag (TMT)-labeled proteomic technique, a total of 3531 proteins were identified in the current study. Compared to the DS strains, there were 247 differentially expressed proteins (DEPs) in the MDR strains and 346 DEPs in the XDR strains, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that a majority of the DEPs were involved in various metabolic pathways, which were beneficial to the evolution of drug resistance in K. pneumoniae. In addition, a total of 67 DEPs were identified between the MDR and XDR strains. KEGG enrichment and protein-protein interaction network analysis showed their participation in cationic antimicrobial peptide resistance and two-component systems. In conclusion, our results highlight the emergence of colistin-resistant and hypervirulent CRKP, which is a noticeable superbug. The DEPs identified in our study are of great significance for the exploration of effective control strategies against infections of CRKP.
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20
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Conceição-Neto OC, da Costa BS, Pontes LDS, Silveira MC, Justo-da-Silva LH, de Oliveira Santos IC, Teixeira CBT, Tavares e Oliveira TR, Hermes FS, Galvão TC, Antunes LCM, Rocha-de-Souza CM, Carvalho-Assef APD. Polymyxin Resistance in Clinical Isolates of K. pneumoniae in Brazil: Update on Molecular Mechanisms, Clonal Dissemination and Relationship With KPC-Producing Strains. Front Cell Infect Microbiol 2022; 12:898125. [PMID: 35909953 PMCID: PMC9334684 DOI: 10.3389/fcimb.2022.898125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/24/2022] [Indexed: 11/14/2022] Open
Abstract
In Brazil, the production of KPC-type carbapenemases in Enterobacteriales is endemic, leading to widespread use of polymyxins. In the present study, 502 Klebsiella pneumoniae isolates were evaluated for resistance to polymyxins, their genetic determinants and clonality, in addition to the presence of carbapenem resistance genes and evaluation of antimicrobial resistance. Resistance to colistin (polymyxin E) was evaluated through initial selection on EMB agar containing 4% colistin sulfate, followed by Minimal Inhibitory Concentration (MIC) determination by broth microdilution. The susceptibility to 17 antimicrobials was assessed by disk diffusion. The presence of blaKPC, blaNDM and blaOXA-48-like carbapenemases was investigated by phenotypic methods and conventional PCR. Molecular typing was performed by PFGE and MLST. Allelic variants of the mcr gene were screened by PCR and chromosomal mutations in the pmrA, pmrB, phoP, phoQ and mgrB genes were investigated by sequencing. Our work showed a colistin resistance frequency of 29.5% (n = 148/502) in K. pneumoniae isolates. Colistin MICs from 4 to >128 µg/mL were identified (MIC50 = 64 µg/mL; MIC90 >128 µg/mL). All isolates were considered MDR, with the lowest resistance rates observed for amikacin (34.4%), and 19.6% of the isolates were resistant to all tested antimicrobials. The blaKPC gene was identified in 77% of the isolates, in consonance with the high rate of resistance to polymyxins related to its use as a therapeutic alternative. Through XbaI-PFGE, 51 pulsotypes were identified. MLST showed 21 STs, with ST437, ST258 and ST11 (CC11) being the most prevalent, and two new STs were determined: ST4868 and ST4869. The mcr-1 gene was identified in 3 K. pneumoniae isolates. Missense mutations in chromosomal genes were identified, as well as insertion sequences in mgrB. Furthermore, the identification of chromosomal mutations in K. pneumoniae isolates belonging from CC11 ensures its success as a high-risk epidemic clone in Brazil and worldwide.
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Affiliation(s)
- Orlando C. Conceição-Neto
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
- Faculdade de Medicina, Universidade Estácio de Sá (UNESA), Rio de Janeiro, Brazil
| | - Bianca Santos da Costa
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Leilane da Silva Pontes
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Melise Chaves Silveira
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | | | - Ivson Cassiano de Oliveira Santos
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Camila Bastos Tavares Teixeira
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Thamirys Rachel Tavares e Oliveira
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Fernanda Stephens Hermes
- Laboratório de Genômica Funcional e Bioinformática (LAGFB), Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, Brazil
| | - Teca Calcagno Galvão
- Laboratório de Genômica Funcional e Bioinformática (LAGFB), Instituto Oswaldo Cruz-FIOCRUZ, Rio de Janeiro, Brazil
| | - L. Caetano M. Antunes
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Cláudio Marcos Rocha-de-Souza
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | - Ana P. D. Carvalho-Assef
- Laboratório de Pesquisa em Infecção Hospitalar (LAPIH), Instituto Oswaldo Cruz - Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
- *Correspondence: Ana P. D. Carvalho-Assef,
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21
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Yang X, Shu R, Hou L, Ren P, Lu X, Huang Z, Zhong Z, Wang H. mcr-1-Mediated In Vitro Inhibition of Plasmid Transfer Is Reversed by the Intestinal Environment. Antibiotics (Basel) 2022; 11:antibiotics11070875. [PMID: 35884129 PMCID: PMC9311533 DOI: 10.3390/antibiotics11070875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 06/21/2022] [Accepted: 06/25/2022] [Indexed: 12/03/2022] Open
Abstract
Colistin is regarded as an antibiotic of last resort against multidrug-resistant Gram-negative bacteria, including Klebsiella pneumoniae and Escherichia coli. Colistin resistance is acquired by microorganisms via chromosome-mediated mutations or plasmid-mediated mobile colistin resistance (mcr) gene, in which the transfer of mcr is the predominant factor underlying the spread of colistin resistance. However, the factors that are responsible for the spread of the mcr gene are still unclear. In this study, we observed that mcr-1 inhibited the transfer of the pHNSHP45 backbone in liquid mating. Similar inhibitory effect of mcr-1.6 and chromosomal mutant ΔmgrB suggested that colistin resistance, acquired from either plasmid or chromosomal mutation, hindered the transfer of colistin resistance-related plasmid in vitro. Dual plasmid system further proved that co-existing plasmid transfer was reduced too. However, this inhibitory effect was reversed in vivo. Some factors in the gut, including bile salt and anaerobic conditions, could increase the transfer frequency of the mcr-1-containing plasmid. Our results demonstrated the potential risk for the spread of colistin resistance in the intestine, provide a scientific basis against the transmission of colistin resistance threat.
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Affiliation(s)
- Xiaoman Yang
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China; (X.Y.); (R.S.); (L.H.); (P.R.); (Z.H.); (Z.Z.)
- Department of Biotechnology, College of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, China
| | - Rundong Shu
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China; (X.Y.); (R.S.); (L.H.); (P.R.); (Z.H.); (Z.Z.)
| | - Leqi Hou
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China; (X.Y.); (R.S.); (L.H.); (P.R.); (Z.H.); (Z.Z.)
| | - Panpan Ren
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China; (X.Y.); (R.S.); (L.H.); (P.R.); (Z.H.); (Z.Z.)
| | - Xin Lu
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, 102206 Beijing, China;
| | - Zhi Huang
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China; (X.Y.); (R.S.); (L.H.); (P.R.); (Z.H.); (Z.Z.)
| | - Zengtao Zhong
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China; (X.Y.); (R.S.); (L.H.); (P.R.); (Z.H.); (Z.Z.)
| | - Hui Wang
- Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China; (X.Y.); (R.S.); (L.H.); (P.R.); (Z.H.); (Z.Z.)
- Correspondence: ; Tel.: +86-25-84396645
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22
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Blair JMA, Zeth K, Bavro VN, Sancho-Vaello E. The role of bacterial transport systems in the removal of host antimicrobial peptides in Gram-negative bacteria. FEMS Microbiol Rev 2022; 46:6617596. [PMID: 35749576 PMCID: PMC9629497 DOI: 10.1093/femsre/fuac032] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 05/23/2022] [Accepted: 06/22/2022] [Indexed: 01/09/2023] Open
Abstract
Antibiotic resistance is a global issue that threatens our progress in healthcare and life expectancy. In recent years, antimicrobial peptides (AMPs) have been considered as promising alternatives to the classic antibiotics. AMPs are potentially superior due to their lower rate of resistance development, since they primarily target the bacterial membrane ('Achilles' heel' of the bacteria). However, bacteria have developed mechanisms of AMP resistance, including the removal of AMPs to the extracellular space by efflux pumps such as the MtrCDE or AcrAB-TolC systems, and the internalization of AMPs to the cytoplasm by the Sap transporter, followed by proteolytic digestion. In this review, we focus on AMP transport as a resistance mechanism compiling all the experimental evidence for the involvement of efflux in AMP resistance in Gram-negative bacteria and combine this information with the analysis of the structures of the efflux systems involved. Finally, we expose some open questions with the aim of arousing the interest of the scientific community towards the AMPs-efflux pumps interactions. All the collected information broadens our understanding of AMP removal by efflux pumps and gives some clues to assist the rational design of AMP-derivatives as inhibitors of the efflux pumps.
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Affiliation(s)
- Jessica M A Blair
- College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Kornelius Zeth
- Department of Science and Environment, Roskilde University, Universitetsvej 1, 4000 Roskilde, Denmark
| | - Vassiliy N Bavro
- School of Life Sciences, University of Essex, Colchester, CO4 3SQ, United Kingdom
| | - Enea Sancho-Vaello
- Corresponding author. College of Medical and Dental Sciences, Institute of Microbiology and Infection, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom. E-mail:
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23
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Targeting the Holy Triangle of Quorum Sensing, Biofilm Formation, and Antibiotic Resistance in Pathogenic Bacteria. Microorganisms 2022; 10:microorganisms10061239. [PMID: 35744757 PMCID: PMC9228545 DOI: 10.3390/microorganisms10061239] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/12/2022] [Accepted: 06/14/2022] [Indexed: 12/12/2022] Open
Abstract
Chronic and recurrent bacterial infections are frequently associated with the formation of biofilms on biotic or abiotic materials that are composed of mono- or multi-species cultures of bacteria/fungi embedded in an extracellular matrix produced by the microorganisms. Biofilm formation is, among others, regulated by quorum sensing (QS) which is an interbacterial communication system usually composed of two-component systems (TCSs) of secreted autoinducer compounds that activate signal transduction pathways through interaction with their respective receptors. Embedded in the biofilms, the bacteria are protected from environmental stress stimuli, and they often show reduced responses to antibiotics, making it difficult to eradicate the bacterial infection. Besides reduced penetration of antibiotics through the intricate structure of the biofilms, the sessile biofilm-embedded bacteria show reduced metabolic activity making them intrinsically less sensitive to antibiotics. Moreover, they frequently express elevated levels of efflux pumps that extrude antibiotics, thereby reducing their intracellular levels. Some efflux pumps are involved in the secretion of QS compounds and biofilm-related materials, besides being important for removing toxic substances from the bacteria. Some efflux pump inhibitors (EPIs) have been shown to both prevent biofilm formation and sensitize the bacteria to antibiotics, suggesting a relationship between these processes. Additionally, QS inhibitors or quenchers may affect antibiotic susceptibility. Thus, targeting elements that regulate QS and biofilm formation might be a promising approach to combat antibiotic-resistant biofilm-related bacterial infections.
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24
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The StkSR Two-Component System Influences Colistin Resistance in Acinetobacter baumannii. Microorganisms 2022; 10:microorganisms10050985. [PMID: 35630428 PMCID: PMC9146086 DOI: 10.3390/microorganisms10050985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/13/2022] [Accepted: 04/22/2022] [Indexed: 01/27/2023] Open
Abstract
Acinetobacter baumannii is an opportunistic human pathogen responsible for numerous severe nosocomial infections. Genome analysis on the A. baumannii clinical isolate 04117201 revealed the presence of 13 two-component signal transduction systems (TCS). Of these, we examined the putative TCS named here as StkSR. The stkR response regulator was deleted via homologous recombination and its progeny, ΔstkR, was phenotypically characterized. Antibiogram analyses of ΔstkR cells revealed a two-fold increase in resistance to the clinically relevant polymyxins, colistin and polymyxin B, compared to wildtype. PAGE-separation of silver stained purified lipooligosaccharide isolated from ΔstkR and wildtype cells ruled out the complete loss of lipooligosaccharide as the mechanism of colistin resistance identified for ΔstkR. Hydrophobicity analysis identified a phenotypical change of the bacterial cells when exposed to colistin. Transcriptional profiling revealed a significant up-regulation of the pmrCAB operon in ΔstkR compared to the parent, associating these two TCS and colistin resistance. These results reveal that there are multiple levels of regulation affecting colistin resistance; the suggested ‘cross-talk’ between the StkSR and PmrAB two-component systems highlights the complexity of these systems.
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25
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Bray AS, Smith RD, Hudson AW, Hernandez GE, Young TM, George HE, Ernst RK, Zafar MA. MgrB-Dependent Colistin Resistance in Klebsiella pneumoniae Is Associated with an Increase in Host-to-Host Transmission. mBio 2022; 13:e0359521. [PMID: 35311534 PMCID: PMC9040857 DOI: 10.1128/mbio.03595-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/08/2022] [Indexed: 12/22/2022] Open
Abstract
Due to its high transmissibility, Klebsiella pneumoniae is one of the leading causes of nosocomial infections. Here, we studied the biological cost of colistin resistance, an antibiotic of last resort, in this opportunistic pathogen using a murine model of gut colonization and transmission. Colistin resistance in K. pneumoniae is commonly the result of the inactivation of the small regulatory protein MgrB. Without a functional MgrB, the two-component system PhoPQ is constitutively active, leading to an increase in lipid A modifications and subsequent colistin resistance. Using an isogenic mgrB deletion mutant (MgrB-), we demonstrate that the mutant's colistin resistance is not associated with a fitness defect under in vitro growth conditions. However, in our murine model of K. pneumoniae gastrointestinal (GI) colonization, the MgrB- colonizes the gut poorly, allowing us to identify a fitness cost. Moreover, the MgrB- mutant has higher survival outside the host compared with the parental strain. We attribute this enhanced survivability to dysregulation of the PhoPQ two-component system and accumulation of the master stress regulator RpoS. The enhanced survival of MgrB- may be critical for its rapid host-to-host transmission observed in our model. Together, our data using multiple clinical isolates demonstrate that MgrB-dependent colistin resistance in K. pneumoniae comes with a biological cost in gut colonization. However, this cost is mitigated by enhanced survival outside the host and consequently increases its host-to-host transmission. Additionally, it underscores the importance of considering the entire life cycle of a pathogen to determine the actual biological cost associated with antibiotic resistance. IMPORTANCE The biological cost associated with colistin resistance in Klebsiella pneumoniae was examined using a murine model of K. pneumoniae gut colonization and fecal-oral transmission. A common mutation resulting in colistin resistance in K. pneumoniae is a loss-of-function mutation of the small regulatory protein MgrB that regulates the two-component system PhoPQ. Even though colistin resistance in K. pneumoniae comes with a fitness defect in gut colonization, it increases bacterial survival outside the host enabling it to transmit more effectively to a new host. The enhanced survival is dependent upon the accumulation of RpoS and dysregulation of the PhoPQ. Hence, our study expands our understanding of the underlying molecular mechanism contributing to the transmission of colistin-resistant K. pneumoniae.
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Affiliation(s)
- Andrew S. Bray
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Richard D. Smith
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland, USA
- Department of Pathology, University of Maryland, Baltimore, Baltimore, Maryland, USA
| | - Andrew W. Hudson
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Giovanna E. Hernandez
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | - Taylor M. Young
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
| | | | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland, Baltimore, Baltimore, Maryland, USA
| | - M. Ammar Zafar
- Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston Salem, North Carolina, USA
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26
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Li F, Cheng P, Li X, Liu R, Liu H, Zhang X. Molecular Epidemiology and Colistin-Resistant Mechanism of mcr-Positive and mcr-Negative Escherichia coli Isolated From Animal in Sichuan Province, China. Front Microbiol 2022; 13:818548. [PMID: 35422787 PMCID: PMC9002323 DOI: 10.3389/fmicb.2022.818548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 02/02/2022] [Indexed: 12/05/2022] Open
Abstract
Colistin is the last line of defense for the treatment of multidrug-resistant gram-negative bacterial infections. However, colistin resistance is gradually increasing worldwide, with resistance commonly regulated by two-component system and mcr gene. Thus, this study aimed to investigate molecular epidemiology and colistin-resistant mechanism of mcr-positive and mcr-negative Escherichia coli isolates from animal in Sichuan Province, China. In this study, a total of 101 colistin-resistant E. coli strains were isolated from 300 fecal samples in six farms in Sichuan Province. PCR was used to detect mcr gene (mcr-1 to mcr-9). The prevalence of mcr-1 in colistin-resistant E. coli was 53.47% (54/101), and the prevalence of mcr-3 in colistin-resistant E. coli was 10.89% (11/101). The colistin-resistant E. coli and mcr-1–positive E. coli showed extensive antimicrobial resistance profiles. For follow-up experiments, we used 30 mcr-negative and 30 mcr-1–positive colistin-resistant E. coli isolates and E. coli K-12 MG1655 model strain. Multi-locus sequence typing (MLST) of 30 strains carrying mcr-1 as detected by PCR identified revealed six strains (20%) of ST10 and three strains (10%) of each ST206, ST48, and ST155 and either two (for ST542 and 2539) or just one for all other types. The conjugation experiment and plasmid replicon type analysis suggest that mcr-1 was more likely to be horizontally transferred and primarily localized on IncX4-type and IncI2-type plasmid. The ST diversity of the mcr-1 indicated a scattered and non-clonal spreading in mcr-1–positive E. coli. Twenty-eight mcr-negative colistin-resistant E. coli isolates carried diverse amino acid alterations in PmrA, PmrB, PhoP, PhoQ, and MgrB, whereas no mutation was found in the remaining isolates. The finding showed the high prevalence of colistin resistance in livestock farm environments in Sichuan Province, China. Our study demonstrates that colistin resistance is related to chromosomal point mutations including the two-component systems PhoP/PhoQ, PmrA/PmrB, and their regulators MgrB. These point mutations may confer colistin resistance in mcr-negative E. coli. These findings help in gaining insight of chromosomal-encoded colistin resistance in E. coli.
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Affiliation(s)
- Fulei Li
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Ping Cheng
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Xiaoting Li
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Ruimeng Liu
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Haibin Liu
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Xiuying Zhang
- Heilongjiang Key Laboratory for Animal Disease Control and Pharmaceutical Development, Northeast Agricultural University, Harbin, China.,Department of Basic Veterinary Science, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
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27
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Elias R, Spadar A, Phelan J, Melo-Cristino J, Lito L, Pinto M, Gonçalves L, Campino S, Clark TG, Duarte A, Perdigão J. A phylogenomic approach for the analysis of colistin resistance associated genes in Klebsiella pneumoniae, its mutational diversity and implications for phenotypic resistance. Int J Antimicrob Agents 2022; 59:106581. [DOI: 10.1016/j.ijantimicag.2022.106581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 02/17/2022] [Accepted: 03/27/2022] [Indexed: 11/05/2022]
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28
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Transcriptomics reveals how minocycline-colistin synergy overcomes antibiotic resistance in multidrug-resistant Klebsiella pneumoniae. Antimicrob Agents Chemother 2022; 66:e0196921. [PMID: 35041511 DOI: 10.1128/aac.01969-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Multidrug resistant gram-negative bacteria are a rapidly growing public health threat, and the development of novel antimicrobials has failed to keep pace with their emergence. Synergistic combinations of individually ineffective drugs present a potential solution, yet little is understood about the mechanisms of most such combinations. Here, we show that the combination of colistin (polymyxin E) and minocycline has a high rate of synergy against colistin-resistant and minocycline-intermediate or -resistant strains of Klebsiella pneumoniae. Furthermore, using RNA-Seq, we characterized the transcriptional profiles of these strains when treated with the drugs individually and in combination. We found a striking similarity between the transcriptional profiles of bacteria treated with the combination of colistin and minocycline at individually subinhibitory concentrations and those of the same isolates treated with minocycline alone. We observed a similar pattern with the combination of polymyxin B nonapeptide (a polymyxin B analogue that lacks intrinsic antimicrobial activity) and minocycline. We also found that genes involved in polymyxin resistance and peptidoglycan biosynthesis showed significant differential gene expression in the different treatment conditions, suggesting possible mechanisms for the antibacterial activity observed in the combination. These findings suggest that the synergistic activity of this combination against bacteria resistant to each drug alone involves sublethal outer membrane disruption by colistin, which permits increased intracellular accumulation of minocycline.
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29
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Escobar‐Salom M, Torrens G, Jordana‐Lluch E, Oliver A, Juan C. Mammals' humoral immune proteins and peptides targeting the bacterial envelope: from natural protection to therapeutic applications against multidrug‐resistant
Gram
‐negatives. Biol Rev Camb Philos Soc 2022; 97:1005-1037. [PMID: 35043558 PMCID: PMC9304279 DOI: 10.1111/brv.12830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 12/12/2021] [Accepted: 12/15/2021] [Indexed: 12/11/2022]
Abstract
Mammalian innate immunity employs several humoral ‘weapons’ that target the bacterial envelope. The threats posed by the multidrug‐resistant ‘ESKAPE’ Gram‐negative pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are forcing researchers to explore new therapeutic options, including the use of these immune elements. Here we review bacterial envelope‐targeting (peptidoglycan and/or membrane‐targeting) proteins/peptides of the mammalian immune system that are most likely to have therapeutic applications. Firstly we discuss their general features and protective activity against ESKAPE Gram‐negatives in the host. We then gather, integrate, and discuss recent research on experimental therapeutics harnessing their bactericidal power, based on their exogenous administration and also on the discovery of bacterial and/or host targets that improve the performance of this endogenous immunity, as a novel therapeutic concept. We identify weak points and knowledge gaps in current research in this field and suggest areas for future work to obtain successful envelope‐targeting therapeutic options to tackle the challenge of antimicrobial resistance.
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Affiliation(s)
- María Escobar‐Salom
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
| | - Gabriel Torrens
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
| | - Elena Jordana‐Lluch
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
| | - Antonio Oliver
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
| | - Carlos Juan
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
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30
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Jamal A, Saleem A, Rezwan F, Sheikh A, Shamsi T. Successful management of colistin- and carbapenem-resistant Klebsiella pneumoniae-associated ecthyma gangrenosum in acute myeloid leukemia: A rare complication. SAGE Open Med Case Rep 2022; 10:2050313X221102113. [PMID: 35655712 PMCID: PMC9152185 DOI: 10.1177/2050313x221102113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 05/02/2022] [Indexed: 11/17/2022] Open
Abstract
Pseudomonal ecthyma gangrenosum is a well-known condition in immunosuppressed patients. However, ecthyma gangrenosum associated with Klebsiella pneumoniae is a rare entity that requires early recognition and optimal antibiotic and surgical management. We herein report the first case of colistin & carbapenem-resistant Klebsiella pneumoniae ecthyma gangrenosum in an acute myeloid leukemia patient. A 30-year-old female with acute myeloid leukemia received induction chemotherapy at the National Institute of Blood Diseases and Bone Marrow Transplantation hospital. Post-chemotherapy, she developed fever and a necrotic erythematous papule on right forearm. Colistin-susceptible carbapenem-resistant Klebsiella pneumoniae was isolated in cultures. Susceptibility testing was performed by microbroth dilution method. Worsening necrotic lesion prompted surgical debridement. Histopathology of debrided tissue revealed necrotic inflammation, and tissue cultures grew colistin-resistant carbapenem-resistant Klebsiella pneumoniae (colistin minimum inhibitory concentration >4 µg/mL). We speculate that colistin resistance was acquired due to impaired antibiotic penetration in necrotic nidus. A higher incidence of carbapenem-resistant Klebsiella pneumoniae-associated ecthyma gangrenosum is anticipated in hem-oncology patients, and timely diagnosis, appropriate antibiotics, and surgical debridement remain the only potential cure.
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Affiliation(s)
- Aisha Jamal
- Department of Clinical Haematology, National Institute of Blood Diseases and Bone Marrow Transplantation, Karachi, Pakistan
| | - Ali Saleem
- Department of Clinical Haematology, National Institute of Blood Diseases and Bone Marrow Transplantation, Karachi, Pakistan
| | - Faiza Rezwan
- Department of Clinical Haematology, National Institute of Blood Diseases and Bone Marrow Transplantation, Karachi, Pakistan
| | - Affaf Sheikh
- Department of Research & Development, National Institute of Blood Diseases and Bone Marrow Transplantation, Karachi, Pakistan
| | - Tahir Shamsi
- Department of Clinical Haematology, National Institute of Blood Diseases and Bone Marrow Transplantation, Karachi, Pakistan
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31
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Masood KI, Umar S, Hasan Z, Farooqi J, Razzak SA, Jabeen N, Rao J, Shakoor S, Hasan R. Lipid A-Ara4N as an alternate pathway for (colistin) resistance in Klebsiella pneumonia isolates in Pakistan. BMC Res Notes 2021; 14:449. [PMID: 34906210 PMCID: PMC8670247 DOI: 10.1186/s13104-021-05867-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 11/29/2021] [Indexed: 11/23/2022] Open
Abstract
Objectives This study aimed to explore mechanism of colistin resistance amongst Klebsiella pneumoniae isolates through plasmid mediated mcr-1 gene in Pakistan. Carbapenem and Colistin resistant K. pneumoniae isolates (n = 34) stored at − 80 °C as part of the Aga Khan University Clinical Laboratory strain bank were randomly selected and subjected to mcr-1 gene PCR. To investigate mechanisms of resistance, other than plasmid mediated mcr-1 gene, whole genome sequencing was performed on 8 clinical isolates, including 6 with colistin resistance (MIC > 4 μg/ml) and 2 with intermediate resistance to colistin (MIC > 2 μg/ml). Results RT-PCR conducted revealed absence of mcr-1 gene in all isolates tested. Whole genome sequencing results revealed modifications in Lipid A-Ara4N pathway. Modifications in Lipid A-Ara4N pathway were detected in ArnA_ DH/FT, UgdH, ArnC and ArnT genes. Mutation in ArnA_ DH/FT gene were detected in S3, S5, S6 and S7 isolates. UgdH gene modifications were found in all isolates except S3, mutations in ArnC were present in all except S1, S2 and S8 and ArnT were detected in all except S4 and S7. In the absence of known mutations linked with colistin resistance, lipid pathway modifications may possibly explain the phenotype resistance to colistin, but this needs further exploration. Supplementary Information The online version contains supplementary material available at 10.1186/s13104-021-05867-3.
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Affiliation(s)
- Kiran Iqbal Masood
- Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan
| | - Seema Umar
- Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan
| | - Zahra Hasan
- Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan
| | - Joveria Farooqi
- Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan
| | - Safina Abdul Razzak
- Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan
| | - Nazish Jabeen
- Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan
| | - Jason Rao
- Health Security Partners, Washington, DC, 20009, USA
| | - Sadia Shakoor
- Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan
| | - Rumina Hasan
- Department of Pathology and Laboratory Medicine, Aga Khan University, Karachi, Pakistan. .,Department of Infection Biology, Faculty Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
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32
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Melander RJ, Mattingly AE, Melander C. Phenotypic screening of compound libraries as a platform for the identification of antibiotic adjuvants: Identification of colistin adjuvants from a natural product library. Methods Enzymol 2021; 665:153-176. [PMID: 35379433 PMCID: PMC10942738 DOI: 10.1016/bs.mie.2021.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The identification of antibiotic adjuvants, small molecules that potentiate the activity of conventional antibiotics, provides an orthogonal approach to the development of new antibiotics in the fight against drug resistant bacterial infections. Methods to identify novel adjuvants could potentially aid efforts to overcome the increasing prevalence of resistance and stave off the onset of a "post-antibiotic era." Phenotypic whole cell screens allow for the identification of hits with the necessary properties to access their biomolecular target, and may also facilitate the discovery of novel adjuvant targets. A phenotypic screening platform is outlined, in which a natural product library was explored for activity with antibiotics from several mechanistically distinct classes against clinically important bacterial species. General approaches to delineating the mechanism of action of hit compounds identified from phenotypic screens are described, followed by specific approaches to uncovering the mechanism of action of the colistin adjuvants identified from the natural product screen.
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Affiliation(s)
- Roberta J Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
| | - Anne E Mattingly
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, United States.
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33
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Shprung T, Wani NA, Wilmes M, Mangoni ML, Bitler A, Shimoni E, Sahl HG, Shai Y. Opposing Effects of PhoPQ and PmrAB on the Properties of Salmonella enterica serovar Typhimurium: Implications on Resistance to Antimicrobial Peptides. Biochemistry 2021; 60:2943-2955. [PMID: 34547893 PMCID: PMC8638962 DOI: 10.1021/acs.biochem.1c00287] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The increasing number of resistant
bacteria is a major threat worldwide,
leading to the search for new antibiotic agents. One of the leading
strategies is the use of antimicrobial peptides (AMPs), cationic and
hydrophobic innate immune defense peptides. A major target of AMPs
is the bacterial membrane. Notably, accumulating data suggest that
AMPs can activate the two-component systems (TCSs) of Gram-negative
bacteria. These include PhoP-PhoQ (PhoPQ) and PmrA-PmrB (PmrAB), responsible
for remodeling of the bacterial cell surface. To better understand
this mechanism, we utilized bacteria deficient either in one system
alone or in both and biophysical tools including fluorescence spectroscopy,
single-cell atomic force microscopy, electron microscopy, and mass
spectrometry (MoskowitzS. M.;Antimicrob. Agents Chemother.2012, 56, 1019−103022106224; ChengH. Y.;J. Biomed. Sci.2010, 17, 6020653976). Our data suggested that the two systems have opposing
effects on the properties of Salmonella enterica. The knockout of PhoPQ made the bacteria more susceptible to AMPs
by making the surface less rigid, more polarized, and permeable with
a slightly more negatively charged cell wall. In addition, the periplasmic
space is thinner. In contrast, the knockout of PmrAB did not affect
its susceptibility, while it made the bacterial outer layer very rigid,
less polarized, and less permeable than the other two mutants, with
a negatively charged cell wall similar to the WT. Overall, the data
suggest that the coexistence of systems with opposing effects on the
biophysical properties of the bacteria contribute to their membrane
flexibility, which, on the one hand, is important to accommodate changing
environments and, on the other hand, may inhibit the development of
meaningful resistance to AMPs.
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Affiliation(s)
- Tal Shprung
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naiem Ahmad Wani
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Miriam Wilmes
- Pharmaceutical Microbiology Section, Institute for Medical Microbiology, Immunology and Parasitology, University of Bonn, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany
| | - Maria Luisa Mangoni
- Department of Biochemical Sciences A. Rossi Fanelli, Faculty of Pharmacy and Medicine, Sapienza University of Rome, CU27, 00185 Roma, Italy
| | - Arkadi Bitler
- Department of Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal Shimoni
- Department of Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Hans-Georg Sahl
- Pharmaceutical Microbiology Section, Institute for Medical Microbiology, Immunology and Parasitology, University of Bonn, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany
| | - Yechiel Shai
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
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34
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Queiroz PA, Meneguello JE, Silva BR, Caleffi-Ferracioli KR, Scodro RB, Cardoso RF, Marchiosi R, Siqueira VL. Proteomic profiling of Klebsiella pneumoniae carbapenemase (KPC)-producer Klebsiella pneumoniae after induced polymyxin resistance. Future Microbiol 2021; 16:1195-1207. [PMID: 34590903 DOI: 10.2217/fmb-2021-0005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: To elucidate the changes in protein expression associated with polymyxin resistance in Klebsiella pneumoniae, we profiled a comparative proteomic analysis of polymyxin B-resistant mutants KPC-2-producing K. pneumoniae, and of its susceptible counterparts. Material & methods: Two-dimensional reversed phase nano ultra-performance liquid chromatography mass spectrometry was used for proteomic analysis. Results: Our results showed that the proteomic profile involved several biological processes, and we highlight the downregulation of outer membrane protein A (OmpA) and the upregulation of SlyB outer membrane lipoprotein (conserved protein member of the PhoPQ regulon) and AcrA multidrug efflux pump in polymyxin B-resistant strains. Conclusion: Our results highlight the possible participation of the SlyB, AcrA and OmpA proteins in the determination of polymyxin B heteroresistance in KPC-2-producing K. pneumoniae.
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Affiliation(s)
- Paula A Queiroz
- Postgraduate Program in Bioscience & Physiopathology, State University of Maringa, Parana, 87020-900, Brazil
| | - Jean E Meneguello
- Postgraduate Program in Bioscience & Physiopathology, State University of Maringa, Parana, 87020-900, Brazil
| | - Bruna R Silva
- Postgraduate Program in Bioscience & Physiopathology, State University of Maringa, Parana, 87020-900, Brazil
| | - Katiany R Caleffi-Ferracioli
- Postgraduate Program in Bioscience & Physiopathology, State University of Maringa, Parana, 87020-900, Brazil.,Laboratory of Medical Bacteriology, Department of Clinical Analysis & Biomedicine, State University of Maringa, Parana, 87020-900, Brazil
| | - Regiane Bl Scodro
- Laboratory of Medical Bacteriology, Department of Clinical Analysis & Biomedicine, State University of Maringa, Parana, 87020-900, Brazil
| | - Rosilene F Cardoso
- Postgraduate Program in Bioscience & Physiopathology, State University of Maringa, Parana, 87020-900, Brazil.,Laboratory of Medical Bacteriology, Department of Clinical Analysis & Biomedicine, State University of Maringa, Parana, 87020-900, Brazil
| | - Rogério Marchiosi
- Department of Biochemistry, State University of Maringa, Maringa, Parana, Brazil
| | - Vera Ld Siqueira
- Postgraduate Program in Bioscience & Physiopathology, State University of Maringa, Parana, 87020-900, Brazil.,Laboratory of Medical Bacteriology, Department of Clinical Analysis & Biomedicine, State University of Maringa, Parana, 87020-900, Brazil
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35
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Palethorpe S, Milton ME, Pesci EC, Cavanagh J. Structure of the Acinetobacter baumannii PmrA receiver domain and insights into clinical mutants affecting DNA-binding and promoting colistin resistance. J Biochem 2021; 170:787-800. [PMID: 34585233 DOI: 10.1093/jb/mvab102] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 09/22/2021] [Indexed: 11/14/2022] Open
Abstract
Acinetobacter baumannii is an insidious emerging nosocomial pathogen that has developed resistance to all available antimicrobials, including the last resort antibiotic, colistin. Colistin resistance often occurs due to mutations in the PmrAB two component regulatory system. To better understand the regulatory mechanisms contributing to colistin resistance, we have biochemically characterized the A. baumannii PmrA response regulator. Initial DNA-binding analysis shows that A. baumannii PmrA bound to the Klebsiella pneumoniae PmrA box motif. This prompted analysis of the putative A. baumannii PmrAB regulon which indicated that the A. baumannii PmrA consensus box is 5'- HTTAAD N5 HTTAAD. Additionally, we provide the first structural information for the A. baumannii PmrA N-terminal domain through X-ray crystallography, and we present a full-length model using molecular modeling. From these studies, we were able to infer the effects of two critical PmrA mutations, PmrA::I13M and PmrA::P102R, both of which confer increased colistin resistance. Based on these data, we suggest structural and dynamic reasons for how these mutations can affect PmrA function and hence encourage resistive traits. Understanding these mechanisms will aid in the development of new targeted antimicrobial therapies.
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Affiliation(s)
- Samantha Palethorpe
- Department of Microbiology and Immunology Brody School of Medicine East Carolina University Greenville, NC 27834 United States
| | - Morgan E Milton
- Department of Biochemistry and Molecular Biology Brody School of Medicine East Carolina University Greenville, NC 27834 United States
| | - Everett C Pesci
- Department of Microbiology and Immunology Brody School of Medicine East Carolina University Greenville, NC 27834 United States
| | - John Cavanagh
- Department of Biochemistry and Molecular Biology Brody School of Medicine East Carolina University Greenville, NC 27834 United States
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36
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Shi H, Li T, Xu J, Yu J, Yang S, Zhang XE, Tao S, Gu J, Deng JY. MgrB Inactivation Confers Trimethoprim Resistance in Escherichia coli. Front Microbiol 2021; 12:682205. [PMID: 34394028 PMCID: PMC8355897 DOI: 10.3389/fmicb.2021.682205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/30/2021] [Indexed: 11/22/2022] Open
Abstract
After several decades of use, trimethoprim (TMP) remains one of the key access antimicrobial drugs listed by the World Health Organization. To circumvent the problem of trimethoprim resistance worldwide, a better understanding of drug-resistance mechanisms is required. In this study, we screened the single-gene knockout library of Escherichia coli, and identified mgrB and other several genes involved in trimethoprim resistance. Subsequent comparative transcriptional analysis between ΔmgrB and the wild-type strain showed that expression levels of phoP, phoQ, and folA were significantly upregulated in ΔmgrB. Further deleting phoP or phoQ could partially restore trimethoprim sensitivity to ΔmgrB, and co-overexpression of phoP/Q caused TMP resistance, suggesting the involvement of PhoP/Q in trimethoprim resistance. Correspondingly, MgrB and PhoP were shown to be able to modulated folA expression in vivo. After that, efforts were made to test if PhoP could directly modulate the expression of folA. Though phosphorylated PhoP could bind to the promotor region of folA in vitro, the former only provided a weak protection on the latter as shown by the DNA footprinting assay. In addition, deleting the deduced PhoP box in ΔmgrB could only slightly reverse the TMP resistance phenotype, suggesting that it is less likely for PhoP to directly modulate the transcription of folA. Taken together, our data suggested that, in E. coli, MgrB affects susceptibility to trimethoprim by modulating the expression of folA with the involvement of PhoP/Q. This work broadens our understanding of the regulation of folate metabolism and the mechanisms of TMP resistance in bacteria.
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Affiliation(s)
- Hongmei Shi
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ting Li
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jintian Xu
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jifang Yu
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Shanshan Yang
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xian-En Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Shengce Tao
- Shanghai Center for Systems Biomedicine, Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Jing Gu
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Jiao-Yu Deng
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,Guangdong Province Key Laboratory of TB Systems Biology and Translational Medicine, Foshan, China
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37
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Di Lorenzo F, Duda KA, Lanzetta R, Silipo A, De Castro C, Molinaro A. A Journey from Structure to Function of Bacterial Lipopolysaccharides. Chem Rev 2021; 122:15767-15821. [PMID: 34286971 DOI: 10.1021/acs.chemrev.0c01321] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Lipopolysaccharide (LPS) is a crucial constituent of the outer membrane of most Gram-negative bacteria, playing a fundamental role in the protection of bacteria from environmental stress factors, in drug resistance, in pathogenesis, and in symbiosis. During the last decades, LPS has been thoroughly dissected, and massive information on this fascinating biomolecule is now available. In this Review, we will give the reader a third millennium update of the current knowledge of LPS with key information on the inherent peculiar carbohydrate chemistry due to often puzzling sugar residues that are uniquely found on it. Then, we will drive the reader through the complex and multifarious immunological outcomes that any given LPS can raise, which is strictly dependent on its chemical structure. Further, we will argue about issues that still remain unresolved and that would represent the immediate future of LPS research. It is critical to address these points to complete our notions on LPS chemistry, functions, and roles, in turn leading to innovative ways to manipulate the processes involving such a still controversial and intriguing biomolecule.
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Affiliation(s)
- Flaviana Di Lorenzo
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Katarzyna A Duda
- Research Center Borstel Leibniz Lung Center, Parkallee 4a, 23845 Borstel, Germany
| | - Rosa Lanzetta
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Alba Silipo
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy
| | - Cristina De Castro
- Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Department of Agricultural Sciences, University of Naples Federico II, Via Università 96, 80055 Portici, Naples, Italy
| | - Antonio Molinaro
- Department of Chemical Sciences, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Via Cinthia 4, 80126 Naples, Italy.,Department of Chemistry, School of Science, Osaka University, 1-1 Osaka University Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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38
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Maynard M, Drusano GL, Vicchiarelli M, Liu W, Myrick J, Nole J, Duncanson B, Brown D, Louie A. Polymyxin B Pharmacodynamics in the Hollow-Fiber Infection Model: What You See May Not Be What You Get. Antimicrob Agents Chemother 2021; 65:e0185320. [PMID: 34097487 PMCID: PMC8284464 DOI: 10.1128/aac.01853-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 04/25/2021] [Indexed: 11/20/2022] Open
Abstract
Dose range studies for polymyxin B (PMB) regimens of 0.75 to 12 mg/kg given every 12 h (q12h) were evaluated for bacterial killing and resistance prevention against an AmpC-overexpressing Pseudomonas aeruginosa and a blaKPC-3-harboring Klebsiella pneumoniae in 10-day in vitro hollow-fiber models. An exposure-response was observed. But all regimens failed due to regrowth. Lower-dose regimens amplified isolates that expressed transient, lower-level adaptive resistance to PMB (MICs ≤ 4 mg/liter). Higher PMB dosages amplified isolates that expressed this resistance mechanism, a higher-MIC "moderately stable" adaptive resistance, and a higher-MIC stable resistance to PMB. Failure of the highest dose regimens was solely due to subpopulations that expressed the two higher-level resistances. Total and bioactive PMB concentrations in broth declined below targeted PK profiles within hours of treatment initiation and prior to bacterial regrowth. With treatment failure, the total PMB measured in bacteria was substantially higher than in broth. But the bioactive PMB in broth and bacteria were low to nondetectable. Together, these findings suggest a sequence of events for treatment failure of the clinical regimen. First, PMB concentrations in broth are diluted as PMB binds to bacteria, resulting in total and bioactive PMB in broth that is lower than targeted. Bacterial regrowth and treatment failure follow, with emergence of subpopulations that express transient lower-level adaptive resistance to PMB and possibly higher-level adaptive and stable resistances. Higher-dose PMB regimens can prevent the emergence of transient lower-level adaptive resistance, but they do not prevent treatment failure due to isolates that express higher-level resistance mechanisms.
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Affiliation(s)
- Michael Maynard
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - G. L. Drusano
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - Michael Vicchiarelli
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - Weiguo Liu
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - Jenny Myrick
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - Jocelyn Nole
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - Brandon Duncanson
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - David Brown
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
| | - Arnold Louie
- Institute for Therapeutic Innovation, University of Florida, Orlando, Florida, USA
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39
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A Molecular Perspective on Colistin and Klebsiella pneumoniae: Mode of Action, Resistance Genetics, and Phenotypic Susceptibility. Diagnostics (Basel) 2021; 11:diagnostics11071165. [PMID: 34202395 PMCID: PMC8305994 DOI: 10.3390/diagnostics11071165] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/11/2021] [Accepted: 06/16/2021] [Indexed: 12/26/2022] Open
Abstract
Klebsiella pneumoniae is a rod-shaped, encapsulated, Gram-negative bacteria associated with multiple nosocomial infections. Multidrug-resistant (MDR) K. pneumoniae strains have been increasing and the therapeutic options are increasingly limited. Colistin is a long-used, polycationic, heptapeptide that has regained attention due to its activity against Gram-negative bacteria, including the MDR K. pneumoniae strains. However, this antibiotic has a complex mode of action that is still under research along with numerous side-effects. The acquisition of colistin resistance is mainly associated with alteration of lipid A net charge through the addition of cationic groups synthesized by the gene products of a multi-genic regulatory network. Besides mutations in these chromosomal genes, colistin resistance can also be achieved through the acquisition of plasmid-encoded genes. Nevertheless, the diversity of molecular markers for colistin resistance along with some adverse colistin properties compromises the reliability of colistin-resistance monitorization methods. The present review is focused on the colistin action and molecular resistance mechanisms, along with specific limitations on drug susceptibility testing for K. pneumoniae.
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40
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Panta PR, Doerrler WT. A link between pH homeostasis and colistin resistance in bacteria. Sci Rep 2021; 11:13230. [PMID: 34168215 PMCID: PMC8225787 DOI: 10.1038/s41598-021-92718-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/14/2021] [Indexed: 12/15/2022] Open
Abstract
Colistin resistance is complex and multifactorial. DbcA is an inner membrane protein belonging to the DedA superfamily required for maintaining extreme colistin resistance of Burkholderia thailandensis. The molecular mechanisms behind this remain unclear. Here, we report that ∆dbcA displays alkaline pH/bicarbonate sensitivity and propose a role of DbcA in extreme colistin resistance of B. thailandensis by maintaining cytoplasmic pH homeostasis. We found that alkaline pH or presence of sodium bicarbonate displays a synergistic effect with colistin against not only extremely colistin resistant species like B. thailandensis and Serratia marcescens, but also a majority of Gram-negative and Gram-positive bacteria tested, suggesting a link between cytoplasmic pH homeostasis and colistin resistance across species. We found that lowering the level of oxygen in the growth media or supplementation of fermentable sugars such as glucose not only alleviated alkaline pH stress, but also increased colistin resistance in most bacteria tested, likely by avoiding cytoplasmic alkalinization. Our observations suggest a previously unreported link between pH, oxygen, and colistin resistance. We propose that maintaining optimal cytoplasmic pH is required for colistin resistance in a majority of bacterial species, consistent with the emerging link between cytoplasmic pH homeostasis and antibiotic resistance.
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Affiliation(s)
- Pradip R Panta
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - William T Doerrler
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
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41
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Various Novel Colistin Resistance Mechanisms Interact To Facilitate Adaptation of Aeromonas hydrophila to Complex Colistin Environments. Antimicrob Agents Chemother 2021; 65:e0007121. [PMID: 33903105 PMCID: PMC8373241 DOI: 10.1128/aac.00071-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Aeromonas hydrophila, a heterotrophic and Gram-negative bacterium, has attracted considerable attention owing to the increasing prevalence of reported infections. Colistin is a last-resort antibiotic that can treat life-threatening infections caused by multidrug-resistant Gram-negative bacteria. However, the mechanisms underlying colistin resistance in A. hydrophila remain unclear. The present study reveals four novel colistin resistance mechanisms in A. hydrophila: (i) EnvZ/OmpR upregulates the expression of the arnBCADTEF operon to mediate lipopolysaccharide (LPS) modification by 4-amino-4-deoxy-l-arabinose, (ii) EnvZ/OmpR regulates the expression of the autotransporter gene3832 to decrease outer membrane permeability in response to colistin, (iii) deletion of envZ/ompR activates PhoP/PhoQ, which functions as a substitute two-component system to mediate the addition of phosphoethanolamine to lipid A via pmrC, and (iv) the mlaFD173A mutant confers high-level colistin resistance via upregulation of the Mla pathway. The EnvZ/OmpR two-component system-mediated resistance mechanism is the leading form of colistin resistance in A. hydrophila, which enables it to rapidly generate low- to medium-level colistin resistance. As colistin concentrations in the environment continue to rise, antibiotic resistance mediated by EnvZ/OmpR becomes insufficient to ensure bacterial survival. Consequently, A. hydrophila has developed an mlaF mutation that results in high-level colistin resistance. Our findings indicate that A. hydrophila can thrive in a complex environment through various colistin resistance mechanisms.
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Abstract
Antibiotic resistance is a major global health challenge and, worryingly, several key Gram negative pathogens can become resistant to most currently available antibiotics. Polymyxins have been revived as a last-line therapeutic option for the treatment of infections caused by multidrug-resistant Gram negative bacteria, in particular Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacterales. Polymyxins were first discovered in the late 1940s but were abandoned soon after their approval in the late 1950s as a result of toxicities (e.g., nephrotoxicity) and the availability of "safer" antibiotics approved at that time. Therefore, knowledge on polymyxins had been scarce until recently, when enormous efforts have been made by several research teams around the world to elucidate the chemical, microbiological, pharmacokinetic/pharmacodynamic, and toxicological properties of polymyxins. One of the major achievements is the development of the first scientifically based dosage regimens for colistin that are crucial to ensure its safe and effective use in patients. Although the guideline has not been developed for polymyxin B, a large clinical trial is currently being conducted to optimize its clinical use. Importantly, several novel, safer polymyxin-like lipopeptides are developed to overcome the nephrotoxicity, poor efficacy against pulmonary infections, and narrow therapeutic windows of the currently used polymyxin B and colistin. This review discusses the latest achievements on polymyxins and highlights the major challenges ahead in optimizing their clinical use and discovering new-generation polymyxins. To save lives from the deadly infections caused by Gram negative "superbugs," every effort must be made to improve the clinical utility of the last-line polymyxins. SIGNIFICANCE STATEMENT: Antimicrobial resistance poses a significant threat to global health. The increasing prevalence of multidrug-resistant (MDR) bacterial infections has been highlighted by leading global health organizations and authorities. Polymyxins are a last-line defense against difficult-to-treat MDR Gram negative pathogens. Unfortunately, the pharmacological information on polymyxins was very limited until recently. This review provides a comprehensive overview on the major achievements and challenges in polymyxin pharmacology and clinical use and how the recent findings have been employed to improve clinical practice worldwide.
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Affiliation(s)
- Sue C Nang
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia (S.C.N., M.A.K.A., J.L.); Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia (T.V.); and Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, West Lafayette, Indiana (Q.T.Z.)
| | - Mohammad A K Azad
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia (S.C.N., M.A.K.A., J.L.); Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia (T.V.); and Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, West Lafayette, Indiana (Q.T.Z.)
| | - Tony Velkov
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia (S.C.N., M.A.K.A., J.L.); Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia (T.V.); and Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, West Lafayette, Indiana (Q.T.Z.)
| | - Qi Tony Zhou
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia (S.C.N., M.A.K.A., J.L.); Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia (T.V.); and Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, West Lafayette, Indiana (Q.T.Z.)
| | - Jian Li
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria, Australia (S.C.N., M.A.K.A., J.L.); Department of Pharmacology and Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, Victoria, Australia (T.V.); and Department of Industrial and Physical Pharmacy, College of Pharmacy, Purdue University, West Lafayette, Indiana (Q.T.Z.)
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Effects of Regulatory Network Organization and Environment on PmrD Connector Activity and Polymyxin Resistance in Klebsiella pneumoniae and Escherichia coli. Antimicrob Agents Chemother 2021; 65:AAC.00889-20. [PMID: 33361295 DOI: 10.1128/aac.00889-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 12/16/2020] [Indexed: 11/20/2022] Open
Abstract
Polymyxins are a class of cyclic peptides with antimicrobial activity against Gram-negative bacteria. In Enterobacteriaceae, the PhoQ/PhoP and PmrB/PmrA two-component systems regulate many genes that confer resistance to both polymyxins and host antimicrobial peptides. The activities of these two-component systems are modulated by additional proteins that are conserved across Enterobacteriaceae, such as MgrB, a negative regulator of PhoQ, and PmrD, a "connector" protein that activates PmrB/PmrA in response to PhoQ/PhoP stimulation. Despite the conservation of many protein components of the PhoQ/PhoP-PmrD-PmrB/PmrA network, the specific molecular interactions and regulatory mechanisms vary across different genera. Here, we explore the role of PmrD in modulating this signaling network in Klebsiella pneumoniae and Escherichia coli We show that in K. pneumoniae, PmrD is not required for polymyxin resistance arising from mutation of mgrB-the most common cause of spontaneous polymyxin resistance in this bacterium-suggesting that direct activation of polymyxin resistance genes by PhoQ/PhoP plays a critical role in this resistance pathway. However, for conditions of low pH or intermediate iron concentrations, both of which stimulate PmrB/PmrA, we find that PmrD does contribute to resistance. We further show that in E. coli, PmrD functions as a connector between PhoQ/PhoP and PmrB/PmrA, in contrast with previous reports. In this case, activity also depends on PmrB/PmrA stimulation, or on very high activation of PhoQ/PhoP. Our results indicate that the importance of the PmrD connector in modulating the polymyxin resistance network depends on both the network organization and on the environmental conditions associated with PmrB stimulation.
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Morales-León F, Opazo-Capurro A, Caro C, Lincopan N, Cardenas-Arias A, Esposito F, Illesca V, Rioseco ML, Domínguez-Yévenes M, Lima CA, Bello-Toledo H, González-Rocha G. Hypervirulent and hypermucoviscous extended-spectrum β-lactamase-producing Klebsiella pneumoniae and Klebsiella variicola in Chile. Virulence 2020; 12:35-44. [PMID: 33372844 PMCID: PMC7781644 DOI: 10.1080/21505594.2020.1859274] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Convergence of virulence and antibiotic-resistance has been reported in Klebsiella pneumoniae, but not in Klebsiella variicola. We, hereby, report the detection and genomic characterization of hypervirulent and hypermucoviscous K. pneumoniae and K.variicola recovered in Chile from health-care associated infections, which displayed resistance to broad-spectrum cephalosporins. One hundred forty-six K. pneumoniae complex isolates were screened by hypermucoviscosity by the “string test.” Two hypermucoid isolates, one hypermucoviscous K. pneumoniae (hmKp) and one K. variicola (hmKv), were further investigated by whole-genome sequencing. In vivo virulence was analyzed by the Galleria mellonella killing assay. In silico analysis of hmKp UCO-494 and hmKv UCO-495 revealed the presence of multiple antibiotic-resistance genes, such as blaCTX-M-1, blaDHA-1 and blaLEN-25 among others clinically relevant resistance determinants, including mutations in a two-component regulatory system related to colistin resistance. These genetic features confer a multidrug-resistant (MDR) phenotype in both strains. Moreover, virulome in silico analysis confirmed the presence of the aerobactin gene iutA, in addition to yersiniabactin and/or colicin V encoding genes, which are normally associated to high virulence in humans. Furthermore, both isolates were able to kill G. mellonella and displayed higher virulence in comparison with the control strain. In summary, the convergence of virulence and the MDR-phenotype in K. pneumoniae complex members is reported for the first time in Chile, denoting a clinical problem that deserves special attention and continuous surveillance in South America.
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Affiliation(s)
- F Morales-León
- Laboratorio de Investigación en Agentes Antibacterianos, Facultad de Ciencias Biológicas, Universidad de Concepción , Concepción, Chile.,Millennium Nucleus for Collaborative Research on Bacterial Resistance , Chile.,Departamento de Farmacia, Universidad de Concepción, Concepción , Chile
| | - A Opazo-Capurro
- Laboratorio de Investigación en Agentes Antibacterianos, Facultad de Ciencias Biológicas, Universidad de Concepción , Concepción, Chile.,Millennium Nucleus for Collaborative Research on Bacterial Resistance , Chile
| | - C Caro
- Laboratorio de Investigación en Agentes Antibacterianos, Facultad de Ciencias Biológicas, Universidad de Concepción , Concepción, Chile.,Departamento de Farmacia, Universidad de Concepción, Concepción , Chile
| | - N Lincopan
- Department of Microbiology, Institute of Biomedical Sciences, Universidade de São Paulo , São Paulo, Brazil.,Department of Clinical Analysis, School of Pharmacy, Universidade de São Paulo , São Paulo, Brazil
| | - A Cardenas-Arias
- Department of Microbiology, Institute of Biomedical Sciences, Universidade de São Paulo , São Paulo, Brazil
| | - F Esposito
- Department of Microbiology, Institute of Biomedical Sciences, Universidade de São Paulo , São Paulo, Brazil.,Department of Clinical Analysis, School of Pharmacy, Universidade de São Paulo , São Paulo, Brazil
| | - V Illesca
- Unidad de Microbiología, Hospital Dr. Hernan Henriquez Aravena , Temuco, Chile
| | - M L Rioseco
- Laboratorio de Microbiologia, Hospital de Puerto Montt , Puerto Montt, Chile
| | - M Domínguez-Yévenes
- Laboratorio de Investigación en Agentes Antibacterianos, Facultad de Ciencias Biológicas, Universidad de Concepción , Concepción, Chile
| | - C A Lima
- Laboratorio de Investigación en Agentes Antibacterianos, Facultad de Ciencias Biológicas, Universidad de Concepción , Concepción, Chile.,Millennium Nucleus for Collaborative Research on Bacterial Resistance , Chile
| | - H Bello-Toledo
- Laboratorio de Investigación en Agentes Antibacterianos, Facultad de Ciencias Biológicas, Universidad de Concepción , Concepción, Chile.,Millennium Nucleus for Collaborative Research on Bacterial Resistance , Chile
| | - Gerardo González-Rocha
- Laboratorio de Investigación en Agentes Antibacterianos, Facultad de Ciencias Biológicas, Universidad de Concepción , Concepción, Chile.,Millennium Nucleus for Collaborative Research on Bacterial Resistance , Chile
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Heterogeneity and Diversity of mcr-8 Genetic Context in Chicken-Associated Klebsiella pneumoniae. Antimicrob Agents Chemother 2020; 65:AAC.01872-20. [PMID: 33046490 DOI: 10.1128/aac.01872-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 10/06/2020] [Indexed: 11/20/2022] Open
Abstract
Increasing mobile colistin resistance, mediated by the mcr gene family, in Enterobacteriaceae has become a global concern. Among the 10 reported mcr genes, mcr-8 was first identified in Klebsiella pneumoniae, which could cause severe infections with high mortality. Information about the prevalence and genetic context of mcr-8 is still lacking. In this study, we found that mcr-8 was present in 9.83% of K. pneumoniae isolates of chicken origin. S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and Southern blotting showed that the mcr-8 gene was located on a plasmid in all of the isolates. The genetic context of the plasmids exhibited considerable diversity from the whole-genome sequence through Illumina and MinION long-read sequencing. Mutations in two-component systems may function synergistically with mcr-8, resulting in extremely high resistance to colistin. In addition to colistin resistance, these plasmids also contained genes conferring resistance to beta-lactams, tetracycline, aminoglycosides, sulfonamides, macrolides, chloramphenicol, and florfenicol. Therefore, these findings indicate that the genetic context of mcr-8 is heterogeneous and diverse and that mcr-8 and certain chromosomal mechanisms jointly contribute to high-level colistin resistance in K. pneumoniae strains, which provides new insights into the resistance mechanisms of K. pneumoniae.
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Mattingly AE, Cox KE, Smith R, Melander RJ, Ernst RK, Melander C. Screening an Established Natural Product Library Identifies Secondary Metabolites That Potentiate Conventional Antibiotics. ACS Infect Dis 2020; 6:2629-2640. [PMID: 32810395 DOI: 10.1021/acsinfecdis.0c00259] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Health organizations worldwide have warned that we are on the cusp of a "post-antibiotic era," necessitating new approaches to combat antibiotic resistant infections. One such approach is the development of antibiotic adjuvants, which have little or no inherent antibiotic activity at their active concentrations but instead potentiate the activity of antibiotics against antibiotic-resistant bacteria. Recently, we demonstrated that meridianin D, a natural product originally reported to have activity against Staphylococcus aureus and Mycobacterium tuberculosis, possesses the ability to reverse colistin resistance in colistin resistant bacteria. As most natural product screens typically involve screening for only certain activities (anticancer, antiviral, and antimicrobial are typical), we posited that the meridianin D discovery was not unique and there are potentially many natural products that have adjuvant activity. To explore this, the National Cancer Institute (NCI) Natural Product Library Set IV was screened for adjuvant activity using four classes of antibiotics (β-lactams, aminoglycosides, macrolides, and polymyxins) against three bacterial pathogens (methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, and Klebsiella pneumoniae). Sixteen compounds suppressed β-lactam resistance in MRSA, five of which effected a 16-fold reduction in the oxacillin minimum inhibitory concentration (MIC). Two natural products effectively suppressed aminoglycoside resistance in both of the Gram-negative species tested, and no hits were observed with macrolides. In contrast, a larger number of natural product adjuvants were identified when screening against colistin-resistant strains of A. baumannii and K. pneumoniae. Nine compounds reduced the colistin MIC to its breakpoint or lower (up to a 1024-fold reduction). Clorobiocin, novobiocin, and prodigiosin were most effective, reducing the colistin MIC in K. pneumoniae strain B9 to 2 μg/mL at concentrations as low as 0.625, 2.5, and 1.25 μM, respectively. Restored sensitivity to colistin with these compounds does not appear to coincide with known mechanisms of colistin resistance.
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Affiliation(s)
- Anne E. Mattingly
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Karlie E. Cox
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Richard Smith
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, Maryland 21201, United States
| | - Roberta J. Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland-Baltimore, Baltimore, Maryland 21201, United States
| | - Christian Melander
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
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Ayoub Moubareck C. Polymyxins and Bacterial Membranes: A Review of Antibacterial Activity and Mechanisms of Resistance. MEMBRANES 2020; 10:membranes10080181. [PMID: 32784516 PMCID: PMC7463838 DOI: 10.3390/membranes10080181] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 12/19/2022]
Abstract
Following their initial discovery in the 1940s, polymyxin antibiotics fell into disfavor due to their potential clinical toxicity, especially nephrotoxicity. However, the dry antibiotic development pipeline, together with the rising global prevalence of infections caused by multidrug-resistant (MDR) Gram-negative bacteria have both rejuvenated clinical interest in these polypeptide antibiotics. Parallel to the revival of their use, investigations into the mechanisms of action and resistance to polymyxins have intensified. With an initial known effect on biological membranes, research has uncovered the detailed molecular and chemical interactions that polymyxins have with Gram-negative outer membranes and lipopolysaccharide structure. In addition, genetic and epidemiological studies have revealed the basis of resistance to these agents. Nowadays, resistance to polymyxins in MDR Gram-negative pathogens is well elucidated, with chromosomal as well as plasmid-encoded, transferrable pathways. The aims of the current review are to highlight the important chemical, microbiological, and pharmacological properties of polymyxins, to discuss their mechanistic effects on bacterial membranes, and to revise the current knowledge about Gram-negative acquired resistance to these agents. Finally, recent research, directed towards new perspectives for improving these old agents utilized in the 21st century, to combat drug-resistant pathogens, is summarized.
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Cheung CHP, Dulyayangkul P, Heesom KJ, Avison MB. Proteomic Investigation of the Signal Transduction Pathways Controlling Colistin Resistance in Klebsiella pneumoniae. Antimicrob Agents Chemother 2020; 64:AAC.00790-20. [PMID: 32457105 PMCID: PMC7526815 DOI: 10.1128/aac.00790-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 05/19/2020] [Indexed: 12/15/2022] Open
Abstract
Colistin resistance in Klebsiella pneumoniae is predominantly caused by mutations that increase expression of the arn (also known as pbg or pmrF) operon. Expression is activated by the PhoPQ and PmrAB two-component systems. Constitutive PhoPQ activation occurs directly by mutation or following loss of MgrB. PhoPQ may also cross-activate PmrAB via the linker protein PmrD. Using proteomics, we show that MgrB loss causes a wider proteomic effect than direct PhoPQ activation, suggesting additional targets for MgrB. Different mgrB mutations cause different amounts of Arn protein production, which correlated with colistin MICs. Disruption of phoP in an mgrB mutant had a reciprocal effect to direct activation of PhoQ in a wild-type background, but the regulated proteins showed almost total overlap. Disruption of pmrD or pmrA slightly reduced Arn protein production in an mgrB mutant, but production was still high enough to confer colistin resistance; disruption of phoP conferred wild-type Arn production and colistin MIC. Activation of PhoPQ directly or through mgrB mutation did not significantly activate PmrAB or PmrC production, but direct activation of PmrAB by mutation was able to do this, and also activated Arn production and conferred colistin resistance. There was little overlap between the PmrAB and PhoPQ regulons. We conclude that under the conditions used for colistin susceptibility testing, PhoPQ-PmrD-PmrAB cross-regulation is not significant and that independent activation of PhoPQ or PmrAB is the main reason that Arn protein production increases above the threshold required for colistin resistance.
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Affiliation(s)
| | - Punyawee Dulyayangkul
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Kate J Heesom
- University of Bristol Proteomics Facility, Bristol, United Kingdom
| | - Matthew B Avison
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
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Choi M, Ko KS. Identification of Genetic Alterations Associated with Acquired Colistin Resistance in Klebsiella pneumoniae Isogenic Strains by Whole-Genome Sequencing. Antibiotics (Basel) 2020; 9:antibiotics9070374. [PMID: 32630683 PMCID: PMC7400116 DOI: 10.3390/antibiotics9070374] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/25/2020] [Accepted: 06/30/2020] [Indexed: 11/16/2022] Open
Abstract
The present study was undertaken to find novel genes associated with colistin resistance in Klebsiella pneumoniae. Five colistin-resistant mutants were derived from four colistin-susceptible parental K. pneumoniae strains belonging to different clones. Whole-genome sequencing was performed for the nine K. pneumoniae strains to screen altered candidate genes. Expression levels of genes with amino acid alterations in derivative strains were determined using quantitative real-time Polymerase chain reaction (PCR). Colistin susceptibility was examined in a parental strain complemented with altered candidate genes. Overall, 13 genetic alterations were identified in five pairs of isogenic K. pneumoniae strains. Genetic alterations related to KP1_3468, including the insertion of an IS5-like element in an intergenic or coding region and amino acid substitutions, were identified in three separate derivative strains. Amino acid substitutions and deletion of PhoQ were determined in one derivative strain. With inactivation of CrrA and substituted CrrB, amino acid substitutions and deletion were identified in a repressor of galETK operon (KP1_0061) and hypothetical protein (KP1_3620), respectively. Decreased colistin susceptibility was observed in a parental strain complemented with KP1-0061, but not a KP1-3620 gene. This study demonstrated diverse genetic paths to colistin resistance in K. pneumoniae. Our results suggest that a repressor of galETK operon may play an important role in colistin resistance in K. pneumoniae.
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Affiliation(s)
| | - Kwan Soo Ko
- Correspondence: ; Tel.: +82-31-299-6223; Fax: +82-31-299-6229
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Pitt ME, Cao MD, Butler MS, Ramu S, Ganesamoorthy D, Blaskovich MAT, Coin LJM, Cooper MA. Octapeptin C4 and polymyxin resistance occur via distinct pathways in an epidemic XDR Klebsiella pneumoniae ST258 isolate. J Antimicrob Chemother 2020; 74:582-593. [PMID: 30445429 DOI: 10.1093/jac/dky458] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Polymyxin B and E (colistin) have been pivotal in the treatment of XDR Gram-negative bacterial infections; however, resistance has emerged. A structurally related lipopeptide, octapeptin C4, has shown significant potency against XDR bacteria, including polymyxin-resistant strains, but its mode of action remains undefined. OBJECTIVES We sought to compare and contrast the acquisition of resistance in an XDR Klebsiella pneumoniae (ST258) clinical isolate in vitro with all three lipopeptides to potentially unveil variations in their mode of action. METHODS The isolate was exposed to increasing concentrations of polymyxins and octapeptin C4 over 20 days. Day 20 strains underwent WGS, complementation assays, antimicrobial susceptibility testing and lipid A analysis. RESULTS Twenty days of exposure to the polymyxins resulted in a 1000-fold increase in the MIC, whereas for octapeptin C4 a 4-fold increase was observed. There was no cross-resistance observed between the polymyxin- and octapeptin-resistant strains. Sequencing of polymyxin-resistant isolates revealed mutations in previously known resistance-associated genes, including crrB, mgrB, pmrB, phoPQ and yciM, along with novel mutations in qseC. Octapeptin C4-resistant isolates had mutations in mlaDF and pqiB, genes related to phospholipid transport. These genetic variations were reflected in distinct phenotypic changes to lipid A. Polymyxin-resistant isolates increased 4-amino-4-deoxyarabinose fortification of lipid A phosphate groups, whereas the lipid A of octapeptin C4-resistant strains harboured a higher abundance of hydroxymyristate and palmitoylate. CONCLUSIONS Octapeptin C4 has a distinct mode of action compared with the polymyxins, highlighting its potential as a future therapeutic agent to combat the increasing threat of XDR bacteria.
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Affiliation(s)
- Miranda E Pitt
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Minh Duc Cao
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Mark S Butler
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Soumya Ramu
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Devika Ganesamoorthy
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Mark A T Blaskovich
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Lachlan J M Coin
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
| | - Matthew A Cooper
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Australia
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