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Tsilipounidaki K, Gkountinoudis CG, Florou Z, Fthenakis GC, Petinaki E. In Silico Molecular Analysis of Carbapenemase-Negative Carbapenem-Resistant Pseudomonas aeruginosa Strains in Greece. Microorganisms 2024; 12:805. [PMID: 38674749 PMCID: PMC11051870 DOI: 10.3390/microorganisms12040805] [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: 03/13/2024] [Revised: 04/02/2024] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
To date, three carbapenem resistance mechanisms have been identified: carbapenemase released from the pathogen, changes in the expression of the outer membrane OprD porin, and overexpression of the efflux pump MexAB-OprM. Twelve carbapenemase-negative carbapenem-resistant Pseudomonas aeruginosa strains, isolated from patients hospitalized at the University Hospital of Larissa, Central Greece, during 2023, which belonged to various sequence types (STs), were selected and were studied focusing on the characterization of their β-lactamases, on changes to OprD and its regulator MexT proteins, and on alterations to the MexAB-OprM regulator proteins encoded by the mexR, nalC, and nalD genes. Whole genome sequencing analysis revealed the presence of β-lactamase encoding genes, with blaPAO present in all isolates. Additionally, seven different genes of the oxacillinase family (blaOXA-35, blaOXA-50, blaOXA-395, blaOXA-396, blaOXA-486, blaOXA-488, blaOXA-494) were identified, with each strain harboring one to three of these. Regarding the OprD, five strains had truncated structures, at Loop 2, Loop 3, Loop 4, and Loop 9, while the remaining strains carried previously reported amino acid changes. Further, an additional strain had a truncated MexR; whereas, two other strains had totally modified NalC sequences. The active form of MexT, responsible for the downregulation of OprD production, as the intact sequence of the NalD protein, was found in all the strains studied. It is concluded that the truncated OprD, MexR, and NalC proteins, detected in eight strains, probably led to inactive proteins, contributing to carbapenem resistance. However, four strains carried known modifications in OprD, MexR, and NalC, as previously reported in both susceptible and resistant strains, a finding that indicates the complexity of carbapenem resistance in P. aeruginosa.
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Affiliation(s)
- Katerina Tsilipounidaki
- Faculty of Medicine, University of Thessaly, 41500 Larissa, Greece; (K.T.); (C.-G.G.); (Z.F.)
| | | | - Zoi Florou
- Faculty of Medicine, University of Thessaly, 41500 Larissa, Greece; (K.T.); (C.-G.G.); (Z.F.)
| | | | - Efthymia Petinaki
- Faculty of Medicine, University of Thessaly, 41500 Larissa, Greece; (K.T.); (C.-G.G.); (Z.F.)
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Upstream region of OprD mutations in imipenem-resistant and imipenem-sensitive Pseudomonas isolates. AMB Express 2021; 11:82. [PMID: 34089411 PMCID: PMC8179858 DOI: 10.1186/s13568-021-01243-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/31/2021] [Indexed: 01/07/2023] Open
Abstract
The current study was aimed at investigating the prevalence of the mutations upstream of the oprD coding region and its promoters among imipenem-resistant and sensitive Pseudomonas aeruginosa isolated from educational hospitals in Yazd City, Iran. All isolates were identified by the conventional biochemical tests. Then, the antibiotic resistance of these isolates was determined using the disk diffusion method according to the CLSI guidelines. Also, the E.test was performed to determine the minimum inhibitory concentrations (MIC) of imipenem. The mutations of this gene were recognized by the amplification of this region and subsequently sequenced. Sequencing of the genomic region upstream of oprD these regions were done in the 29 clinical strains. Statistical analysis was done by the statistical software SPSS-18. Seventy (77.7%) of isolates had MIC ≥ 16 and were resistant to imipenem. Mutations of the upstream of the oprD gene and its promoters were seen in 25 (86.2%) isolates and 4 isolates had no mutation. One isolate had a base substitution A→Cat nt 25 in the coding region and this isolate had a point mutation leading to an amino acid change at positions 9 (I→L). Our study results indicated that none of the strains had mutation in Shine-Dalgarno and the point mutations were the most common mutations upstream of the oprD coding region among P. aeruginosa isolates. Mutations were observed in imipenem-resistant isolates and it seems this mechanism is effective in resistance of isolates to imipenem and this confirmed that the indiscriminate use of antibiotic should be controlled.
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Transcriptomic Analysis of Pseudomonas aeruginosa Response to Pine Honey via RNA Sequencing Indicates Multiple Mechanisms of Antibacterial Activity. Foods 2021; 10:foods10050936. [PMID: 33923242 PMCID: PMC8145095 DOI: 10.3390/foods10050936] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 04/19/2021] [Accepted: 04/22/2021] [Indexed: 12/12/2022] Open
Abstract
Pine honey is a unique type of honeydew honey produced exclusively in Eastern Mediterranean countries like Greece and Turkey. Although the antioxidant and anti-inflammatory properties of pine honey are well documented, few studies have investigated so far its antibacterial activity. This study investigates the antibacterial effects of pine honey against P. aeruginosa PA14 at the molecular level using a global transcriptome approach via RNA-sequencing. Pine honey treatment was applied at sub-inhibitory concentration and short exposure time (0.5× of minimum inhibitory concentration –MIC- for 45 min). Pine honey induced the differential expression (>two-fold change and p ≤ 0.05) of 463 genes, with 274 of them being down-regulated and 189 being up-regulated. Gene ontology (GO) analysis revealed that pine honey affected a wide range of biological processes (BP). The most affected down-regulated BP GO terms were oxidation-reduction process, transmembrane transport, proteolysis, signal transduction, biosynthetic process, phenazine biosynthetic process, bacterial chemotaxis, and antibiotic biosynthetic process. The up-regulated BP terms, affected by pine honey treatment, were those related to the regulation of DNA-templated transcription, siderophore transport, and phosphorylation. Pathway analysis revealed that pine honey treatment significantly affected two-component regulatory systems, ABC transporter systems, quorum sensing, bacterial chemotaxis, biofilm formation and SOS response. These data collectively indicate that multiple mechanisms of action are implicated in antibacterial activity exerted by pine honey against P. aeruginosa.
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Horner C, Mushtaq S, Livermore DM. Potentiation of imipenem by relebactam for Pseudomonas aeruginosa from bacteraemia and respiratory infections. J Antimicrob Chemother 2020; 74:1940-1944. [PMID: 31032858 DOI: 10.1093/jac/dkz133] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/22/2019] [Accepted: 03/05/2019] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Imipenem resistance in Pseudomonas aeruginosa most often entails loss of the 'carbapenem-specific' porin OprD; more rarely it reflects acquired carbapenemases. Loss of OprD only confers resistance to imipenem if AmpC β-lactamase is expressed, and we investigated whether this mechanism was overcome by relebactam, a developmental diazabicyclooctane β-lactamase inhibitor. METHODS Consecutive P. aeruginosa isolates causing bacteraemia or hospital-onset lower respiratory tract infections were collected between 2014 and 2016 under the aegis of the BSAC Resistance Surveillance Programme. Imipenem MICs were determined centrally by BSAC agar dilution, with relebactam at a fixed concentration (4 mg/L). RESULTS For most imipenem-susceptible P. aeruginosa (726/759, 95.7%), the MICs of imipenem alone were 0.5-2 mg/L and were decreased 3- to 4-fold by addition of relebactam, as based on geometric means or modes. For most imipenem-resistant P. aeruginosa (82/92, 89%), imipenem MICs were 8-16 mg/L, and were reduced to 1-2 mg/L by relebactam. These patterns applied regardless of whether the isolates were susceptible to penicillins and cephalosporins or had phenotypes suggesting derepressed AmpC or up-regulated efflux. Imipenem MICs for five P. aeruginosa with MBLs remained high (≥16 mg/L) regardless of relebactam. CONCLUSIONS Potentiation of imipenem by relebactam was almost universal, in accordance with the view that endogenous pseudomonal AmpC ordinarily protects against this carbapenem to a small degree. Imipenem MICs were reduced to the current breakpoint, or lower, except for MBL producers. Potentiation was not compromised by derepression of AmpC or up-regulation of efflux.
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Affiliation(s)
- Carolyne Horner
- British Society for Antimicrobial Chemotherapy, Birmingham, UK
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Suresh M, Skariyachan S, Narayanan N, Pullampara Rajamma J, Panickassery Ramakrishnan MK. Mutational Variation Analysis of oprD Porin Gene in Multidrug-Resistant Clinical Isolates of Pseudomonas aeruginosa. Microb Drug Resist 2020; 26:869-879. [PMID: 32083512 DOI: 10.1089/mdr.2019.0147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The present study deals with the outer membrane OprD porin protein in 29 clinical bacterial isolates of multidrug-resistant Pseudomonas aeruginosa. oprD porin gene expression was investigated using real-time reverse transcription-PCR. Amplicons from oprD and its transcriptional regulator mexT gene were sequenced and analyzed for mutations. Hypothetical models of selected mutant OprD-porin proteins were predicted and refined by homology modeling approach. oprD ampliconic sequences were also screened for restriction fragment length polymorphism (RFLP). The oprD gene was found to be downregulated in 89.7% (n = 26) of the isolates in comparison to the transcript levels in the reference strain P. aeruginosa-PAO (MTCC-3541). Interestingly, all these isolates displayed the presence of a conspicuous 8-bp deletion (GGCCAGCC) at nucleotide position 235 of mexT regulatory gene. Based on the mutational patterns observed in oprD gene, the isolates were classified into categories designated as A, B1-2, C1-4, D1-6, E1-2, and F. Our hypothetical models revealed that mutations were predominantly confined to the extracellular loops emanating from the β-barrel porin protein. These protein models also enabled clear visualization of loss of substantial portions of the truncated polypeptide. Incidentally, since most of the oprD amplicons of the clinical isolates were found to display distinct RFLP banding patterns, our results also provide a useful diagnostic tool for detection of P. aeruginosa porin mutants.
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Affiliation(s)
- Manju Suresh
- Department of Biotechnology, University of Calicut, Malappuram, India
| | | | - Nithya Narayanan
- Department of Biotechnology, University of Calicut, Malappuram, India
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Abstract
Acinetobacter baumannii is nowadays a relevant nosocomial pathogen characterized by multidrug resistance (MDR) and concomitant difficulties to treat infections. OmpA is the most abundant A. baumannii outer membrane (OM) protein, and is involved in virulence, host-cell recognition, biofilm formation, regulation of OM stability, permeability and antibiotic resistance. OmpA members are two-domain proteins with an N-terminal eight-stranded β-barrel domain with four external loops (ELs) interacting with the environment, and a C-terminal periplasmic domain binding non-covalently to the peptidoglycan. Here, we combined data from genome sequencing, phylogenetic and multilocus sequence analyses from 975 strains/isolates of the Acinetobacter calcoaceticus/Acinetobacter baumannii complex (ACB), 946 from A. baumannii, to explore ompA microevolutionary divergence. Five major ompA variant groups were identified (V1 to V5) in A. baumannii, encompassing 52 different alleles coding for 23 different proteins. Polymorphisms were concentrated in five regions corresponding to the four ELs and the C-terminal end, and provided evidence for intra-genic recombination. ompA variants were not randomly distributed across the A. baumannii phylogeny, with the most frequent V1(lct)a1 allele found in most clonal complex 2 (CC2) strains and the second most frequent V2(lct)a1 allele in the majority of CC1 strains. Evidence was found for assortative exchanges of ompA alleles not only between separate A. baumannii lineages, but also different ACB species. The overall results have implications for A. baumannii evolution, epidemiology, virulence and vaccine design.
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Affiliation(s)
- Alejandro M Viale
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET) and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario (UNR), 2000 Rosario, Argentina
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Abstract
Gram-negative carbapenem-resistant bacteria are a major threat to global health. The use of genome-wide screening approaches to probe for genes or mutations enabling resistance can lead to identification of molecular markers for diagnostics applications. We describe an approach called Mut-Seq that couples chemical mutagenesis and next-generation sequencing for studying resistance to imipenem in the Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The use of this approach highlighted shared and species-specific responses, and the role in resistance of a number of genes involved in membrane biogenesis, transcription, and signal transduction was functionally validated. Interestingly, some of the genes identified were previously considered promising therapeutic targets. Our genome-wide screen has the potential to be extended outside drug resistance studies and expanded to other organisms. Carbapenem-resistant Gram-negative bacteria are considered a major threat to global health. Imipenem (IMP) is used as a last line of treatment against these pathogens, but its efficacy is diminished by the emergence of resistance. We applied a whole-genome screen in Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa isolates that were submitted to chemical mutagenesis, selected for IMP resistance, and characterized by next-generation sequencing. A comparative analysis of IMP-resistant clones showed that most of the highly mutated genes shared by the three species encoded proteins involved in transcription or signal transduction. Of these, the rpoD gene was one of the most prevalent and an E. coli strain disrupted for rpoD displayed a 4-fold increase in resistance to IMP. E. coli and K. pneumoniae also specifically shared several mutated genes, most involved in membrane/cell envelope biogenesis, and the contribution in IMP susceptibility was experimentally proven for amidases, transferases, and transglycosidases. P. aeruginosa differed from the two Enterobacteriaceae isolates with two different resistance mechanisms, with one involving mutations in the oprD porin or, alternatively, in two-component systems. Our chemogenomic screen performed with the three species has highlighted shared and species-specific responses to IMP. IMPORTANCE Gram-negative carbapenem-resistant bacteria are a major threat to global health. The use of genome-wide screening approaches to probe for genes or mutations enabling resistance can lead to identification of molecular markers for diagnostics applications. We describe an approach called Mut-Seq that couples chemical mutagenesis and next-generation sequencing for studying resistance to imipenem in the Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The use of this approach highlighted shared and species-specific responses, and the role in resistance of a number of genes involved in membrane biogenesis, transcription, and signal transduction was functionally validated. Interestingly, some of the genes identified were previously considered promising therapeutic targets. Our genome-wide screen has the potential to be extended outside drug resistance studies and expanded to other organisms.
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A large-scale whole-genome comparison shows that experimental evolution in response to antibiotics predicts changes in naturally evolved clinical Pseudomonas aeruginosa. Antimicrob Agents Chemother 2019:AAC.01619-19. [PMID: 31570397 DOI: 10.1128/aac.01619-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that causes a wide range of acute and chronic infections. An increasing number of isolates have mutations that make them antibiotic resistant, making treatment difficult. To identify resistance-associated mutations we experimentally evolved the antibiotic sensitive strain P. aeruginosa PAO1 to become resistant to three widely used anti-pseudomonal antibiotics, ciprofloxacin, meropenem and tobramycin. Mutants could tolerate up to 2048-fold higher concentrations of antibiotic than strain PAO1. Genome sequences were determined for thirteen mutants for each antibiotic. Each mutant had between 2 and 8 mutations. For each antibiotic at least 8 genes were mutated in multiple mutants, demonstrating the genetic complexity of resistance. For all three antibiotics mutations arose in genes known to be associated with resistance, but also in genes not previously associated with resistance. To determine the clinical relevance of mutations uncovered in this study we analysed the corresponding genes in 558 isolates of P. aeruginosa from patients with chronic lung disease and in 172 isolates from the general environment. Many genes identified through experimental evolution had predicted function-altering changes in clinical isolates but not in environmental isolates, showing that mutated genes in experimentally evolved bacteria can predict those that undergo mutation during infection. Additionally, large deletions of up to 479kb arose in experimentally evolved meropenem resistant mutants and large deletions were present in 87 of the clinical isolates. These findings significantly advance understanding of antibiotic resistance in P. aeruginosa and demonstrate the validity of experimental evolution in identifying clinically-relevant resistance-associated mutations.
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D'Arrigo I, Cardoso JGR, Rennig M, Sonnenschein N, Herrgård MJ, Long KS. Analysis of Pseudomonas putida growth on non-trivial carbon sources using transcriptomics and genome-scale modelling. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:87-97. [PMID: 30298597 DOI: 10.1111/1758-2229.12704] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 10/02/2018] [Accepted: 10/03/2018] [Indexed: 06/08/2023]
Abstract
Pseudomonas putida is characterized by a versatile metabolism and stress tolerance traits that allow the bacterium to cope with different environmental conditions. In this work, the mechanisms that allow P. putida KT2440 to grow in the presence of four sole carbon sources (glucose, citrate, ferulic acid, serine) were investigated by RNA sequencing (RNA-seq) and genome-scale metabolic modelling. Transcriptomic data identified uptake systems for the four carbon sources, and candidates were subjected to preliminary experimental characterization by mutant strain growth to test their involvement in substrate assimilation. The OpdH and BenF-like porins were involved in citrate and ferulic acid uptake respectively. The citrate transporter (encoded by PP_0147) and the TctABC system were important for supporting cell growth in citrate; PcaT and VanK were associated with ferulic acid uptake; and the ABC transporter AapJPQM was involved in serine transport. A genome-scale metabolic model of P. putida KT2440 was used to integrate and analyze the transcriptomic data, identifying and confirming the active catabolic pathways for each carbon source. This study reveals novel information about transporters that are essential for understanding bacterial adaptation to different environments.
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Affiliation(s)
- Isotta D'Arrigo
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, DK-2800, Kongens Lyngby, Denmark
| | - João G R Cardoso
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, DK-2800, Kongens Lyngby, Denmark
| | - Maja Rennig
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, DK-2800, Kongens Lyngby, Denmark
| | - Nikolaus Sonnenschein
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, DK-2800, Kongens Lyngby, Denmark
| | - Markus J Herrgård
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, DK-2800, Kongens Lyngby, Denmark
| | - Katherine S Long
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, DK-2800, Kongens Lyngby, Denmark
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Sood U, Hira P, Kumar R, Bajaj A, Rao DLN, Lal R, Shakarad M. Comparative Genomic Analyses Reveal Core-Genome-Wide Genes Under Positive Selection and Major Regulatory Hubs in Outlier Strains of Pseudomonas aeruginosa. Front Microbiol 2019; 10:53. [PMID: 30787911 PMCID: PMC6372532 DOI: 10.3389/fmicb.2019.00053] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/14/2019] [Indexed: 12/11/2022] Open
Abstract
Genomic information for outlier strains of Pseudomonas aeruginosa is exiguous when compared with classical strains. We sequenced and constructed the complete genome of an environmental strain CR1 of P. aeruginosa and performed the comparative genomic analysis. It clustered with the outlier group, hence we scaled up the analyses to understand the differences in environmental and clinical outlier strains. We identified eight new regions of genomic plasticity and a plasmid pCR1 with a VirB/D4 complex followed by trimeric auto-transporter that can induce virulence phenotype in the genome of strain CR1. Virulence genotype analysis revealed that strain CR1 lacked hemolytic phospholipase C and D, three genes for LPS biosynthesis and had reduced antibiotic resistance genes when compared with clinical strains. Genes belonging to proteases, bacterial exporters and DNA stabilization were found to be under strong positive selection, thus facilitating pathogenicity and survival of the outliers. The outliers had the complete operon for the production of vibrioferrin, a siderophore present in plant growth promoting bacteria. The competence to acquire multidrug resistance and new virulence factors makes these strains a potential threat. However, we identified major regulatory hubs that can be used as drug targets against both the classical and outlier groups.
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Affiliation(s)
- Utkarsh Sood
- Department of Zoology, University of Delhi, New Delhi, India
- PhiXGen Private Limited, Gurugram, India
| | - Princy Hira
- Department of Zoology, University of Delhi, New Delhi, India
| | - Roshan Kumar
- Department of Zoology, University of Delhi, New Delhi, India
- PhiXGen Private Limited, Gurugram, India
- Department of Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD, United States
| | - Abhay Bajaj
- Department of Zoology, University of Delhi, New Delhi, India
- National Centre for Microbial Resource, National Centre for Cell Science, Pune, India
| | | | - Rup Lal
- Department of Zoology, University of Delhi, New Delhi, India
- PhiXGen Private Limited, Gurugram, India
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Morales S, A Gallego M, Vanegas JM, Jiménez JN. Detection of carbapenem resistance genes in Pseudomonas aeruginosa isolates with several phenotypic susceptibility profiles. ACTA ACUST UNITED AC 2018. [DOI: 10.21615/cesmedicina.32.3.2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Introduction: Pseudomonas aeruginosa display several resistance mechanisms to carbapenems and such variety makes it difficult to infer from the antibiogram. The aim of this study was to determine the carbapenem resistance genes in P. aeruginosa isolates with different profiles of phenotypic susceptibility to these antibiotics.
Materials and methods: From a microbial collection of P. aeruginosa isolates from infected patients, 40 isolates with different carbapenem resistance profiles were selected. The carbapenemases genes, and expression of the OprD porin, the MexAB-OprM efflux pump and the β-lactamase AmpC were determined.
Results: From a total of 40 isolates evaluted, in 21 (52.5%) any mechanism of resistance evaluated were detected. In the meropenem-resistant group, overexpression of AmpC (n = 1) and decreased expression of MexAB-OprM (n = 2) and OprD (n = 1) were found. A decrease in the expression of MexAB-OprM was observed in imipenem-resistant group (n = 3) and mutations in the gene encoding the OprD porin (n = 1). Finally, the presence of carbapenemases (VIM, n= 3, KPC-2 / VIM, n = 1) was detected in imipenem-meropenem resistant isolates.
Conclusion: The phenotypic susceptibility profiles in P. aeruginosa isolates were not explained by the molecular mechanisms explored, with the exception of carbapenemase-producing isolates. These results evidence the complexity of the antibiotic resistance mechanisms involved in this bacterium.
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Johnning A, Karami N, Tång Hallbäck E, Müller V, Nyberg L, Buongermino Pereira M, Stewart C, Ambjörnsson T, Westerlund F, Adlerberth I, Kristiansson E. The resistomes of six carbapenem-resistant pathogens - a critical genotype-phenotype analysis. Microb Genom 2018; 4. [PMID: 30461373 PMCID: PMC6321870 DOI: 10.1099/mgen.0.000233] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Carbapenem resistance is a rapidly growing threat to our ability to treat refractory bacterial infections. To understand how carbapenem resistance is mobilized and spread between pathogens, it is important to study the genetic context of the underlying resistance mechanisms. In this study, the resistomes of six clinical carbapenem-resistant isolates of five different species – Acinetobacter baumannii, Escherichia coli, two Klebsiella pneumoniae, Proteus mirabilis and Pseudomonas aeruginosa – were characterized using whole genome sequencing. All Enterobacteriaceae isolates and the A. baumannii isolate had acquired a large number of antimicrobial resistance genes (7–18 different genes per isolate), including the following encoding carbapenemases: blaKPC-2, blaOXA-48, blaOXA-72, blaNDM-1, blaNDM-7 and blaVIM-1. In addition, a novel version of blaSHV was discovered. Four new resistance plasmids were identified and their fully assembled sequences were verified using optical DNA mapping. Most of the resistance genes were co-localized on these and other plasmids, suggesting a risk for co-selection. In contrast, five out of six carbapenemase genes were present on plasmids with no or few other resistance genes. The expected level of resistance – based on acquired resistance determinants – was concordant with measured levels in most cases. There were, however, several important discrepancies for four of the six isolates concerning multiple classes of antibiotics. In conclusion, our results further elucidate the diversity of carbapenemases, their mechanisms of horizontal transfer and possible patterns of co-selection. The study also emphasizes the difficulty of using whole genome sequencing for antimicrobial susceptibility testing of pathogens with complex genotypes.
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Affiliation(s)
- Anna Johnning
- 2Centre for Antibiotic Resistance Research, CARe, University of Gothenburg, Gothenburg, Sweden.,1Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Nahid Karami
- 2Centre for Antibiotic Resistance Research, CARe, University of Gothenburg, Gothenburg, Sweden.,3Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Erika Tång Hallbäck
- 3Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Vilhelm Müller
- 4Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Lena Nyberg
- 4Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Mariana Buongermino Pereira
- 1Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.,2Centre for Antibiotic Resistance Research, CARe, University of Gothenburg, Gothenburg, Sweden
| | - Callum Stewart
- 5Department of Astronomy and Theoretical Physics, Lund University, Lund, Sweden
| | - Tobias Ambjörnsson
- 5Department of Astronomy and Theoretical Physics, Lund University, Lund, Sweden
| | - Fredrik Westerlund
- 4Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Ingegerd Adlerberth
- 2Centre for Antibiotic Resistance Research, CARe, University of Gothenburg, Gothenburg, Sweden.,3Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Erik Kristiansson
- 1Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.,2Centre for Antibiotic Resistance Research, CARe, University of Gothenburg, Gothenburg, Sweden
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Multi-drug resistant Pseudomonas aeruginosa nosocomial strains: Molecular epidemiology and evolution. Microb Pathog 2018; 123:233-241. [DOI: 10.1016/j.micpath.2018.07.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 06/27/2018] [Accepted: 07/17/2018] [Indexed: 11/18/2022]
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van der Zee A, Kraak WB, Burggraaf A, Goessens WHF, Pirovano W, Ossewaarde JM, Tommassen J. Spread of Carbapenem Resistance by Transposition and Conjugation Among Pseudomonas aeruginosa. Front Microbiol 2018; 9:2057. [PMID: 30233535 PMCID: PMC6133989 DOI: 10.3389/fmicb.2018.02057] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Accepted: 08/13/2018] [Indexed: 12/14/2022] Open
Abstract
The emergence of carbapenem-resistant Pseudomonas aeruginosa represents a worldwide problem. To understand the carbapenem-resistance mechanisms and their spreading among P. aeruginosa strains, whole genome sequences were determined of two extensively drug-resistant strains that are endemic in Dutch hospitals. Strain Carb01 63 is of O-antigen serotype O12 and of sequence type ST111, whilst S04 90 is a serotype O11 strain of ST446. Both strains carry a gene for metallo-β-lactamase VIM-2 flanked by two aacA29 genes encoding aminoglycoside acetyltransferases on a class 1 integron. The integron is located on the chromosome in strain Carb01 63 and on a plasmid in strain S04 90. The backbone of the 159-kb plasmid, designated pS04 90, is similar to a previously described plasmid, pND6-2, from Pseudomonas putida. Analysis of the context of the integron showed that it is present in both strains on a ∼30-kb mosaic DNA segment composed of four different transposons that can presumably act together as a novel, active, composite transposon. Apart from the presence of a 1237-bp insertion sequence element in the composite transposon on pS04 90, these transposons show > 99% sequence identity indicating that transposition between plasmid and chromosome could have occurred only very recently. The pS04 90 plasmid could be transferred by conjugation to a susceptible P. aeruginosa strain. A second class 1 integron containing a gene for a CARB-2 β-lactamase flanked by an aacA4′-8 and an aadA2 gene, encoding an aminoglycoside acetyltransferase and adenylyltransferase, respectively, was present only in strain Carb01 63. This integron is located also on a composite transposon that is inserted in an integrative and conjugative element on the chromosome. Additionally, this strain contains a frameshift mutation in the oprD gene encoding a porin involved in the transport of carbapenems across the outer membrane. Together, the results demonstrate that integron-encoded carbapenem and carbapenicillin resistance can easily be disseminated by transposition and conjugation among Pseudomonas aeruginosa strains.
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Affiliation(s)
- Anneke van der Zee
- Laboratory of Medical Microbiology, Molecular Diagnostics Unit, Maasstad Hospital, Rotterdam, Netherlands
| | - W Bart Kraak
- Laboratory of Medical Microbiology, Molecular Diagnostics Unit, Maasstad Hospital, Rotterdam, Netherlands
| | - Arjan Burggraaf
- Laboratory of Medical Microbiology, Molecular Diagnostics Unit, Maasstad Hospital, Rotterdam, Netherlands
| | | | | | - Jacobus M Ossewaarde
- Laboratory of Medical Microbiology, Molecular Diagnostics Unit, Maasstad Hospital, Rotterdam, Netherlands.,Erasmus University Medical Center, Rotterdam, Netherlands
| | - Jan Tommassen
- Section Molecular Microbiology, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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15
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Courtois N, Caspar Y, Maurin M. Phenotypic and genetic resistance traits of Pseudomonas aeruginosa strains infecting cystic fibrosis patients: A French cohort study. Int J Antimicrob Agents 2018; 52:358-364. [DOI: 10.1016/j.ijantimicag.2018.05.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 04/09/2018] [Accepted: 05/08/2018] [Indexed: 11/16/2022]
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16
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Shu JC, Kuo AJ, Su LH, Liu TP, Lee MH, Su IN, Wu TL. Development of carbapenem resistance in Pseudomonas aeruginosa is associated with OprD polymorphisms, particularly the amino acid substitution at codon 170. J Antimicrob Chemother 2018; 72:2489-2495. [PMID: 28535274 DOI: 10.1093/jac/dkx158] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/28/2017] [Indexed: 12/13/2022] Open
Abstract
Objectives Pan-susceptible Pseudomonas aeruginosa (PSPA) clinical isolates carrying an OprD with loop 7 shortening (the group-1A allele) were found to rapidly develop carbapenem resistance under continuous selection pressure. We further studied whether OprD polymorphisms are associated with the potential to develop carbapenem resistance. Methods OprD amino acid sequences of 126 PSPA clinical isolates were analysed to determine their STs using P. aeruginosa strain PAO1 as the control strain. Site-directed mutagenesis was performed in PAO1 to generate polymorphisms of interest. A disc diffusion method was used to select carbapenem-resistant variants from the mutant strains. Expression levels of oprD were determined by quantitative RT-PCR. MICs of carbapenems were determined by Etest. Results Forty-eight (38.1%) of the tested isolates carried the group-1A allele. Another two major STs, C1 and C2, both of which harboured an F170L polymorphism, were found in 21 (16.7%) and 39 (31.0%) isolates, respectively. The PAO1 type was also found in 14 (11.1%) isolates. Under continuous selective pressure, isolates of most STs developed carbapenem resistance at different numbers of passaging events; only those belonging to the PAO1 type remained susceptible. However, PAO1 mutants carrying either the oprD group-1A allele or the OprD-F170L polymorphism were able to develop carbapenem resistance. Reduced oprD expression triggered by continuous imipenem challenge was found in PAO1 mutants, but not in the PAO1 WT strain. Conclusions OprD polymorphisms, particularly the F170L substitution and the specific shortening in loop 7, appear to determine the potential for P. aeruginosa to develop carbapenem resistance.
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Affiliation(s)
- Jwu-Ching Shu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan, Taiwan.,Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - An-Jing Kuo
- Department of Laboratory Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan, Taiwan.,Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Lin-Hui Su
- Department of Laboratory Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan, Taiwan.,Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Tsui-Ping Liu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan, Taiwan
| | - Ming-Hsun Lee
- Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - I-Ning Su
- Department of Laboratory Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan, Taiwan
| | - Tsu-Lan Wu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital Linkou, Taoyuan, Taiwan.,Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
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17
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Heterogeneous Antimicrobial Susceptibility Characteristics in Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients. mSphere 2018; 3:mSphere00615-17. [PMID: 29564400 PMCID: PMC5853491 DOI: 10.1128/msphere.00615-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 02/08/2018] [Indexed: 11/22/2022] Open
Abstract
Patients with cystic fibrosis endure “chronic focal infections” with a variety of microorganisms. One microorganism, Pseudomonas aeruginosa, adapts to the host and develops resistance to a wide range of antimicrobials. Interestingly, as the infection progresses, multiple isogenic strains of P. aeruginosa emerge and coexist within the airways of these patients. Despite a common parental origin, the multiple strains of P. aeruginosa develop vastly different susceptibility patterns to actively used antimicrobial agents—a phenomenon we define as “heterogeneous MICs.” By sequencing pairs of P. aeruginosa isolates displaying heterogeneous MICs, we observed widespread isogenic gene lesions in drug transporters, DNA mismatch repair mechanisms, and many other structural or cellular functions. Coupled with the heterogeneous MICs, these genetic lesions demonstrated a symbiotic response to host selection and suggested evolution of a multicellular syntrophic bacterial lifestyle. Current laboratory standard interpretive criteria do not address the emergence of heterogeneous growth and susceptibilities in vitro with treatment implications. Clinical isolates of Pseudomonas aeruginosa from patients with cystic fibrosis (CF) are known to differ from those associated with non-CF hosts by colony morphology, drug susceptibility patterns, and genomic hypermutability. Pseudomonas aeruginosa isolates from CF patients have long been recognized for their overall reduced rate of antimicrobial susceptibility, but their intraclonal MIC heterogeneity has long been overlooked. Using two distinct cohorts of clinical strains (n = 224 from 56 CF patients, n = 130 from 68 non-CF patients) isolated in 2013, we demonstrated profound Etest MIC heterogeneity in CF P. aeruginosa isolates in comparison to non-CF P. aeruginosa isolates. On the basis of whole-genome sequencing of 19 CF P. aeruginosa isolates from 9 patients with heterogeneous MICs, the core genome phylogenetic tree confirmed the within-patient CF P. aeruginosa clonal lineage along with considerable coding sequence variability. No extrachromosomal DNA elements or previously characterized antibiotic resistance mutations could account for the wide divergence in antimicrobial MICs between P. aeruginosa coisolates, though many heterogeneous mutations in efflux and porin genes and their regulators were present. A unique OprD sequence was conserved among the majority of isolates of CF P. aeruginosa analyzed, suggesting a pseudomonal response to selective pressure that is common to the isolates. Genomic sequence data also suggested that CF pseudomonal hypermutability was not entirely due to mutations in mutL, mutS, and uvr. We conclude that the net effect of hundreds of adaptive mutations, both shared between clonally related isolate pairs and unshared, accounts for their highly heterogeneous MIC variances. We hypothesize that this heterogeneity is indicative of the pseudomonal syntrophic-like lifestyle under conditions of being “locked” inside a host focal airway environment for prolonged periods. IMPORTANCE Patients with cystic fibrosis endure “chronic focal infections” with a variety of microorganisms. One microorganism, Pseudomonas aeruginosa, adapts to the host and develops resistance to a wide range of antimicrobials. Interestingly, as the infection progresses, multiple isogenic strains of P. aeruginosa emerge and coexist within the airways of these patients. Despite a common parental origin, the multiple strains of P. aeruginosa develop vastly different susceptibility patterns to actively used antimicrobial agents—a phenomenon we define as “heterogeneous MICs.” By sequencing pairs of P. aeruginosa isolates displaying heterogeneous MICs, we observed widespread isogenic gene lesions in drug transporters, DNA mismatch repair machinery, and many other structural or cellular functions. Coupled with the heterogeneous MICs, these genetic lesions demonstrated a symbiotic response to host selection and suggested evolution of a multicellular syntrophic bacterial lifestyle. Current laboratory standard interpretive criteria do not address the emergence of heterogeneous growth and susceptibilities in vitro with treatment implications.
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18
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Schiavano GF, Carloni E, Andreoni F, Magi S, Chironna M, Brandi G, Amagliani G. Prevalence and antibiotic resistance of Pseudomonas aeruginosa in water samples in central Italy and molecular characterization of oprD in imipenem resistant isolates. PLoS One 2017; 12:e0189172. [PMID: 29211780 PMCID: PMC5718518 DOI: 10.1371/journal.pone.0189172] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/20/2017] [Indexed: 12/18/2022] Open
Abstract
Scope This study aimed to analyse the prevalence, antibiotic resistance and genetic relatedness of P. aeruginosa isolates obtained from potable and recreational water samples (n. 8,351) collected from different settings (swimming pools, n. 207; healthcare facilities, n 1,684; accommodation facilities, n. 1,518; municipal waterworks, n. 4,500; residential buildings, n. 235). Possible mechanisms underlying resistance to imipenem, with particular focus on those involving oprD-based uptake, were also explored. Methods and results Isolation and identification of Pseudomonas aeruginosa was performed according to the standardized procedure UNI EN ISO 16266:2008 followed by PCR confirmation. Antibiotic Susceptibility testing was conducted according to EUCAST standardized disk diffusion method. Genetic relatedness of strains was carried out by RAPD. The sequence of the oprD gene was analyzed by standard method. Fifty-three samples (0.63%) were positive for P. aeruginosa, of which 10/207 (4.83%) were from swimming pools. Five isolates (9.43%) were resistant to imipenem, one to Ticarcillin + Clavulanate, one to both Piperacillin and Ticarcillin + Clavulanate. The highest isolation rate of imipenem resistant P. aeruginosa was observed in swimming pool water. Identical RAPD profiles were found in isolates from the same location in the same year or even in different years. Conclusions Imipenem resistant strains were identified as carbapenemase-negative and resistance has been associated with inactivating mutations within the oprD gene, with a concomitant loss of porin. RAPD results proved that a water system can remain colonized by one strain for long periods and the contamination may be difficult to eradicate. This study has revealed the presence of P. aeruginosa in different water samples, including resistant strains, especially in swimming pools, and confirmed the role of porins as a contributing factor in carbapenem resistance in Gram-negative bacteria.
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Affiliation(s)
- Giuditta Fiorella Schiavano
- Department of Biomolecular Sciences, Toxicological, Hygienistic and Environmental Sciences Unit, University of Urbino Carlo Bo, Urbino, PU, Italy
- * E-mail:
| | - Elisa Carloni
- Department of Biomolecular Sciences, Section of Biotechnology, University of Urbino Carlo Bo, Fano, PU, Italy
| | - Francesca Andreoni
- Department of Biomolecular Sciences, Section of Biotechnology, University of Urbino Carlo Bo, Fano, PU, Italy
| | - Silvia Magi
- Dipartimento provinciale ARPAM di Pesaro, Servizio Acque, Pesaro, Italy
| | - Maria Chironna
- Department of Biomedical Science and Human Oncology-Hygiene Section, Aldo Moro University of Bari, Bari, Italy
| | - Giorgio Brandi
- Department of Biomolecular Sciences, Toxicological, Hygienistic and Environmental Sciences Unit, University of Urbino Carlo Bo, Urbino, PU, Italy
| | - Giulia Amagliani
- Department of Biomolecular Sciences, Toxicological, Hygienistic and Environmental Sciences Unit, University of Urbino Carlo Bo, Urbino, PU, Italy
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19
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Zhang YF, Han K, Chandler CE, Tjaden B, Ernst RK, Lory S. Probing the sRNA regulatory landscape of P. aeruginosa: post-transcriptional control of determinants of pathogenicity and antibiotic susceptibility. Mol Microbiol 2017; 106:919-937. [PMID: 28976035 PMCID: PMC5738928 DOI: 10.1111/mmi.13857] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2017] [Indexed: 01/01/2023]
Abstract
During environmental adaptation bacteria use small regulatory RNAs (sRNAs) to repress or activate expression of a large fraction of their proteome. We extended the use of the in vivo RNA proximity ligation method toward probing global sRNA interactions with their targets in Pseudomonas aeruginosa and verified the method with a known regulon controlled by the PrrF1 sRNA. We also identified two sRNAs (Sr0161 and ErsA) that interact with the mRNA encoding the major porin OprD responsible for the uptake of carbapenem antibiotics. These two sRNAs base pair with the 5' UTR of oprD leading to increase in resistance of the bacteria to meropenem. Additional proximity ligation experiments and enrichment for Sr0161 targets identified the mRNA for the regulator of type III secretion system. Interaction between the exsA mRNA and Sr0161 leads to a block in the synthesis of a component of the T3SS apparatus and an effector. Another sRNA, Sr006, positively regulates, without Hfq, the expression of PagL, an enzyme responsible for deacylation of lipid A, reducing its pro-inflammatory property and resulting in polymyxin resistance. Therefore, an analysis of global sRNA-mRNA interactions can lead to discoveries of novel pathways controlling gene expression that are likely integrated into larger regulatory networks.
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Affiliation(s)
- Yi-Fan Zhang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
- Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Kook Han
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Courtney E. Chandler
- Department of Microbial Pathogenesis, University of Maryland – Baltimore, School of Dentistry, Baltimore, Maryland, USA
| | - Brian Tjaden
- Computer Science Department, Wellesley College, Wellesley, Massachusetts, USA
| | - Robert K. Ernst
- Department of Microbial Pathogenesis, University of Maryland – Baltimore, School of Dentistry, Baltimore, Maryland, USA
| | - Stephen Lory
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA
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20
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Chevalier S, Bouffartigues E, Bodilis J, Maillot O, Lesouhaitier O, Feuilloley MGJ, Orange N, Dufour A, Cornelis P. Structure, function and regulation of Pseudomonas aeruginosa porins. FEMS Microbiol Rev 2017; 41:698-722. [PMID: 28981745 DOI: 10.1093/femsre/fux020] [Citation(s) in RCA: 200] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/24/2017] [Indexed: 12/11/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative bacterium belonging to the γ-proteobacteria. Like other members of the Pseudomonas genus, it is known for its metabolic versatility and its ability to colonize a wide range of ecological niches, such as rhizosphere, water environments and animal hosts, including humans where it can cause severe infections. Another particularity of P. aeruginosa is its high intrinsic resistance to antiseptics and antibiotics, which is partly due to its low outer membrane permeability. In contrast to Enterobacteria, pseudomonads do not possess general diffusion porins in their outer membrane, but rather express specific channel proteins for the uptake of different nutrients. The major outer membrane 'porin', OprF, has been extensively investigated, and displays structural, adhesion and signaling functions while its role in the diffusion of nutrients is still under discussion. Other porins include OprB and OprB2 for the diffusion of glucose, the two small outer membrane proteins OprG and OprH, and the two porins involved in phosphate/pyrophosphate uptake, OprP and OprO. The remaining nineteen porins belong to the so-called OprD (Occ) family, which is further split into two subfamilies termed OccD (8 members) and OccK (11 members). In the past years, a large amount of information concerning the structure, function and regulation of these porins has been published, justifying why an updated review is timely.
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Affiliation(s)
- Sylvie Chevalier
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, Normandy University, 27000 Evreux, France
| | - Emeline Bouffartigues
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, Normandy University, 27000 Evreux, France
| | - Josselin Bodilis
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, Normandy University, 27000 Evreux, France
| | - Olivier Maillot
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, Normandy University, 27000 Evreux, France
| | - Olivier Lesouhaitier
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, Normandy University, 27000 Evreux, France
| | - Marc G J Feuilloley
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, Normandy University, 27000 Evreux, France
| | - Nicole Orange
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, Normandy University, 27000 Evreux, France
| | - Alain Dufour
- IUEM, Laboratoire de Biotechnologie et Chimie Marines EA 3884, Université de Bretagne-Sud (UEB), 56321 Lorient, France
| | - Pierre Cornelis
- Laboratory of Microbiology Signals and Microenvironment LMSM EA 4312, University of Rouen, Normandy University, 27000 Evreux, France
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21
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Identification of 1-((2,4-Dichlorophenethyl)Amino)-3-Phenoxypropan-2-ol, a Novel Antibacterial Compound Active against Persisters of Pseudomonas aeruginosa. Antimicrob Agents Chemother 2017. [PMID: 28630188 DOI: 10.1128/aac.00836-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Antibiotics typically fail to completely eradicate a bacterial population, leaving a small fraction of transiently antibiotic-tolerant persister cells intact. Persisters are therefore seen to be a major cause of treatment failure and greatly contribute to the recalcitrant nature of chronic infections. The current study focused on Pseudomonas aeruginosa, a Gram-negative pathogen belonging to the notorious ESKAPE group of pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) and, due to increasing resistance against most conventional antibiotics, posing a serious threat to human health. Greatly contributing to the difficult treatment of P. aeruginosa infections is the presence of persister cells, and elimination of these cells would therefore significantly improve patient outcomes. In this study, a small-molecule library was screened for compounds that, in combination with the fluoroquinolone antibiotic ofloxacin, reduced the number of P. aeruginosa persisters compared to the number achieved with treatment with the antibiotic alone. Based on the early structure-activity relationship, 1-((2,4-dichlorophenethyl)amino)-3-phenoxypropan-2-ol (SPI009) was selected for further characterization. Combination of SPI009 with mechanistically distinct classes of antibiotics reduced the number of persisters up to 106-fold in both lab strains and clinical isolates of P. aeruginosa Further characterization of the compound revealed a direct and efficient killing of persister cells. SPI009 caused no erythrocyte damage and demonstrated minor cytotoxicity. In conclusion, we identified a novel antipersister compound active against P. aeruginosa with promising applications for the design of novel, case-specific combination therapies in the fight against chronic infections.
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22
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Haidar G, Philips NJ, Shields RK, Snyder D, Cheng S, Potoski BA, Doi Y, Hao B, Press EG, Cooper VS, Clancy CJ, Nguyen MH. Ceftolozane-Tazobactam for the Treatment of Multidrug-Resistant Pseudomonas aeruginosa Infections: Clinical Effectiveness and Evolution of Resistance. Clin Infect Dis 2017; 65:110-120. [PMID: 29017262 PMCID: PMC5848332 DOI: 10.1093/cid/cix182] [Citation(s) in RCA: 205] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Accepted: 02/24/2017] [Indexed: 12/22/2022] Open
Abstract
Background Data on the use of ceftolozane-tazobactam and emergence of ceftolozane-tazobactam resistance during multidrug resistant (MDR)-Pseudomonas aeruginosa infections are limited. Methods We performed a retrospective study of 21 patients treated with ceftolozane-tazobactam for MDR-P. aeruginosa infections. Whole genome sequencing and quantitative real-time polymerase chain reaction were performed on longitudinal isolates. Results Median age was 58 years; 9 patients (43%) were transplant recipients. Median simplified acute physiology score-II (SAPS-II) was 26. Eighteen (86%) patients were treated for respiratory tract infections; others were treated for bloodstream, complicated intraabdominal infections, or complicated urinary tract infections. Ceftolozane-tazobactam was discontinued in 1 patient (rash). Thirty-day all-cause and attributable mortality rates were 10% (2/21) and 5% (1/21), respectively; corresponding 90-day mortality rates were 48% (10/21) and 19% (4/21). The ceftolozane-tazobactam failure rate was 29% (6/21). SAPS-II score was the sole predictor of failure. Ceftolozane-tazobactam resistance emerged in 3 (14%) patients. Resistance was associated with de novo mutations, rather than acquisition of resistant nosocomial isolates. ampC overexpression and mutations were identified as potential resistance determinants. Conclusions In this small study, ceftolozane-tazobactam was successful in treating 71% of patients with MDR-P. aeruginosa infections, most of whom had pneumonia. The emergence of ceftolozane-tazobactam resistance in 3 patients is worrisome and may be mediated in part by AmpC-related mechanisms. More research on treatment responses and resistance during various types of MDR-P. aeruginosa infections is needed to define ceftolozane-tazobactam's place in the armamentarium.
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Affiliation(s)
- Ghady Haidar
- Department of Medicine, University of Pittsburgh
| | - Nathan J Philips
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine
| | - Ryan K Shields
- Department of Medicine, University of Pittsburgh
- Antibiotic Management Program, and
- XDR Pathogen Laboratory, University of Pittsburgh Medical Center
| | - Daniel Snyder
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine
| | - Shaoji Cheng
- XDR Pathogen Laboratory, University of Pittsburgh Medical Center
| | - Brian A Potoski
- Department of Medicine, University of Pittsburgh
- Antibiotic Management Program, and
- Department of Pharmacy and Therapeutics, University of Pittsburgh, and
| | - Yohei Doi
- Department of Medicine, University of Pittsburgh
| | - Binghua Hao
- XDR Pathogen Laboratory, University of Pittsburgh Medical Center
| | | | - Vaughn S Cooper
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine
| | - Cornelius J Clancy
- Department of Medicine, University of Pittsburgh
- XDR Pathogen Laboratory, University of Pittsburgh Medical Center
- VA Pittsburgh Healthcare System, Pennsylvania
| | - M Hong Nguyen
- Department of Medicine, University of Pittsburgh
- Antibiotic Management Program, and
- XDR Pathogen Laboratory, University of Pittsburgh Medical Center
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Vassilara F, Galani I, Souli M, Papanikolaou K, Giamarellou H, Papadopoulos A. Mechanisms responsible for imipenem resistance among Pseudomonas aeruginosa clinical isolates exposed to imipenem concentrations within the mutant selection window. Diagn Microbiol Infect Dis 2017; 88:276-281. [PMID: 28434899 DOI: 10.1016/j.diagmicrobio.2017.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 03/30/2017] [Accepted: 04/07/2017] [Indexed: 10/19/2022]
Abstract
The aim of this study was to determine the propensities of imipenem to select for resistant Pseudomonas aeruginosa mutants by determining the mutant prevention concentrations (MPCs) for 9 unrelated clinical isolates and the accession of any relationship with mechanisms of resistance development. The MPC/MIC ratios ranged from 4 to 16. Detection of resistance mechanisms in the mutant derivatives of the nine isolates mainly revealed inactivating mutations in the gene coding for outer membrane protein OprD. Point mutations leading to premature stop codons or amino acid substitution S278P, ≥1bp deletion leading to frameshift mutations and interruption of the oprD by an insertion sequence, were observed. MPC and mutant selection window (MSW) are unique parameters that may guide the implementation of antimicrobial treatment, providing useful information about the necessary imipenem concentration needed in the infection area, in order to avoid the emergence of resistance, especially in clinical situations with high bacterial load.
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Affiliation(s)
| | - Irene Galani
- Infectious Diseases Laboratory, 4th Department of Internal Medicine, University General Hospital "Attikon", Medical School, National and Kapodistrian University of Athens, Athens, Greece.
| | - Maria Souli
- Infectious Diseases Laboratory, 4th Department of Internal Medicine, University General Hospital "Attikon", Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | | | - Helen Giamarellou
- 6th Department of Internal Medicine, Hygeia General Hospital, Athens, Greece
| | - Antonios Papadopoulos
- Infectious Diseases Laboratory, 4th Department of Internal Medicine, University General Hospital "Attikon", Medical School, National and Kapodistrian University of Athens, Athens, Greece
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24
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Kos VN, McLaughlin RE, Gardner HA. Identification of unique in-frame deletions in OprD among clinical isolates of Pseudomonas aeruginosa. Pathog Dis 2016; 74:ftw031. [PMID: 27073254 DOI: 10.1093/femspd/ftw031] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2016] [Indexed: 12/21/2022] Open
Abstract
A large percentage of Pseudomonas aeruginosa clinical isolates have been noted to be resistant to carbapenems due to loss of function of the OprD porin, the primary mechanism of entry for carbapenems. Such modifications also substantially abolish the organism's ability to transport arginine. Here we report the identification of an in-frame deletion in oprD which confers carbapenem resistance but is expressed and retains the ability to transport arginine.
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Affiliation(s)
- Veronica N Kos
- Infection Innovative Medicines Unit, AstraZeneca R&D Boston, 35 Gatehouse Drive, Waltham, MA 02451, USA
| | - Robert E McLaughlin
- Infection Innovative Medicines Unit, AstraZeneca R&D Boston, 35 Gatehouse Drive, Waltham, MA 02451, USA
| | - Humphrey A Gardner
- Early Clinical Development Innovative Medicines Unit, AstraZeneca R&D Boston, Waltham, MA 02451, USA
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25
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Mutant Alleles of lptD Increase the Permeability of Pseudomonas aeruginosa and Define Determinants of Intrinsic Resistance to Antibiotics. Antimicrob Agents Chemother 2015; 60:845-54. [PMID: 26596941 DOI: 10.1128/aac.01747-15] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 11/15/2015] [Indexed: 01/11/2023] Open
Abstract
Gram-negative bacteria provide a particular challenge to antibacterial drug discovery due to their cell envelope structure. Compound entry is impeded by the lipopolysaccharide (LPS) of the outer membrane (OM), and those molecules that overcome this barrier are often expelled by multidrug efflux pumps. Understanding how efflux and permeability affect the ability of a compound to reach its target is paramount to translating in vitro biochemical potency to cellular bioactivity. Herein, a suite of Pseudomonas aeruginosa strains were constructed in either a wild-type or efflux-null background in which mutations were engineered in LptD, the final protein involved in LPS transport to the OM. These mutants were demonstrated to be defective in LPS transport, resulting in compromised barrier function. Using isogenic strain sets harboring these newly created alleles, we were able to define the contributions of permeability and efflux to the intrinsic resistance of P. aeruginosa to a variety of antibiotics. These strains will be useful in the design and optimization of future antibiotics against Gram-negative pathogens.
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Mathlouthi N, Areig Z, Al Bayssari C, Bakour S, Ali El Salabi A, Ben Gwierif S, Zorgani AA, Ben Slama K, Chouchani C, Rolain JM. Emergence of Carbapenem-Resistant Pseudomonas aeruginosa and Acinetobacter baumannii Clinical Isolates Collected from Some Libyan Hospitals. Microb Drug Resist 2015; 21:335-41. [DOI: 10.1089/mdr.2014.0235] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Affiliation(s)
- Najla Mathlouthi
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
- Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Campus Universitaire, Université de Tunis El-Manar, El-Manar, Tunisie
| | - Zaynab Areig
- Infection Control Office, Benghazi Medical Centre, Benghazi, Libya
- Department of Microbiology, The Libyan Academy, Benghazi, Libya
| | - Charbel Al Bayssari
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
| | - Sofiane Bakour
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
| | - Allaaeddin Ali El Salabi
- Infection Control Office, Benghazi Medical Centre, Benghazi, Libya
- Department of Environmental Health, Faculty of Public Health, University of Benghazi, Benghazi, Libya
| | - Salha Ben Gwierif
- Department of Microbiology, The Libyan Academy, Benghazi, Libya
- Department of Botany, University of Benghazi, Benghazi, Libya
| | - Abdulaziz A. Zorgani
- Department of Medical Microbiology and Immunology, Faculty of Medicine, University of Tripoli, Libya
| | - Karim Ben Slama
- Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Campus Universitaire, Université de Tunis El-Manar, El-Manar, Tunisie
| | - Chedly Chouchani
- Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Campus Universitaire, Université de Tunis El-Manar, El-Manar, Tunisie
- Université de Carthage, Institut Supérieur des Sciences et Technologies de l'Environnement de Borj-Cedria, Hammam-Lif, Tunisie
| | - Jean-Marc Rolain
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE), UM 63, CNRS 7278, IRD 198, INSERM 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille-Université, Marseille, France
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Isabella V, Campbell A, Manchester J, Sylvester M, Nayar A, Ferguson K, Tommasi R, Miller A. Toward the Rational Design of Carbapenem Uptake in Pseudomonas aeruginosa. ACTA ACUST UNITED AC 2015; 22:535-547. [DOI: 10.1016/j.chembiol.2015.03.018] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 03/14/2015] [Accepted: 03/27/2015] [Indexed: 12/22/2022]
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Stepanyan K, Wenseleers T, Duéñez-Guzmán EA, Muratori F, Van den Bergh B, Verstraeten N, De Meester L, Verstrepen KJ, Fauvart M, Michiels J. Fitness trade-offs explain low levels of persister cells in the opportunistic pathogen Pseudomonas aeruginosa. Mol Ecol 2015; 24:1572-83. [PMID: 25721227 DOI: 10.1111/mec.13127] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 01/09/2015] [Accepted: 02/13/2015] [Indexed: 02/03/2023]
Abstract
Microbial populations often contain a fraction of slow-growing persister cells that withstand antibiotics and other stress factors. Current theoretical models predict that persistence levels should reflect a stable state in which the survival advantage of persisters under adverse conditions is balanced with the direct growth cost impaired under favourable growth conditions, caused by the nonreplication of persister cells. Based on this direct growth cost alone, however, it remains challenging to explain the observed low levels of persistence (<<1%) seen in the populations of many species. Here, we present data from the opportunistic human pathogen Pseudomonas aeruginosa that can explain this discrepancy by revealing various previously unknown costs of persistence. In particular, we show that in the absence of antibiotic stress, increased persistence is traded off against a lengthened lag phase as well as a reduced survival ability during stationary phase. We argue that these pleiotropic costs contribute to the very low proportions of persister cells observed among natural P. aeruginosa isolates (3 × 10(-8) -3 × 10(-4)) and that they can explain why strains with higher proportions of persister cells lose out very quickly in competition assays under favourable growth conditions, despite a negligible difference in maximal growth rate. We discuss how incorporating these trade-offs could lead to models that can better explain the evolution of persistence in nature and facilitate the rational design of alternative therapeutic strategies for treating infectious diseases.
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Affiliation(s)
- Kristine Stepanyan
- Centre of Microbial and Plant Genetics, KU Leuven - University of Leuven, Kasteelpark Arenberg 20 bus 2460, 3001 Leuven, Belgium
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Charretier Y, Köhler T, Cecchini T, Bardet C, Cherkaoui A, Llanes C, Bogaerts P, Chatellier S, Charrier JP, Schrenzel J. Label-free SRM-based relative quantification of antibiotic resistance mechanisms in Pseudomonas aeruginosa clinical isolates. Front Microbiol 2015; 6:81. [PMID: 25713571 PMCID: PMC4322712 DOI: 10.3389/fmicb.2015.00081] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 01/22/2015] [Indexed: 12/26/2022] Open
Abstract
Both acquired and intrinsic mechanisms play a crucial role in Pseudomonas aeruginosa antibiotic resistance. Many clinically relevant resistance mechanisms result from changes in gene expression, namely multidrug efflux pump overproduction, AmpC β-lactamase induction or derepression, and inactivation or repression of the carbapenem-specific porin OprD. Changes in gene expression are usually assessed using reverse-transcription quantitative real-time PCR (RT-qPCR) assays. Here, we evaluated label-free Selected Reaction Monitoring (SRM)-based mass spectrometry to directly quantify proteins involved in antibiotic resistance. We evaluated the label-free SRM using a defined set of P. aeruginosa isolates with known resistance mechanisms and compared it with RT-qPCR. Referring to efflux systems, we found a more robust relative quantification of antibiotic resistance mechanisms by SRM than RT-qPCR. The SRM-based approach was applied to a set of clinical P. aeruginosa isolates to detect antibiotic resistance proteins. This multiplexed SRM-based approach is a rapid and reliable method for the simultaneous detection and quantification of resistance mechanisms and we demonstrate its relevance for antibiotic resistance prediction.
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Affiliation(s)
- Yannick Charretier
- Genomic Research Laboratory, Service of Infectious Diseases, Geneva University Hospitals Geneva, Switzerland
| | - Thilo Köhler
- Department of Microbiology and Molecular Medicine, University of Geneva Geneva, Switzerland
| | - Tiphaine Cecchini
- Institute for Analytical Sciences, Joint Research Unit 5280 CNRS/Lyon 1 University Villeurbanne, France ; Technology Research Department, BioMérieux SA Marcy l'Etoile, France
| | - Chloé Bardet
- UMR1092 INSERM, Limoges University Limoges, France ; MD3, BioMérieux SA Marcy l'Etoile, France
| | - Abdessalam Cherkaoui
- Laboratory of Bacteriology, Department of Genetic and Laboratory Medicine, Geneva University Hospitals Geneva, Switzerland
| | - Catherine Llanes
- Laboratoire de Bactériologie, EA4266, Université de Franche-Comté Besançon, France
| | - Pierre Bogaerts
- Laboratoire de Microbiologie, CHU Dinant-Godinne UCL Namur Yvoir, Belgique
| | | | | | - Jacques Schrenzel
- Genomic Research Laboratory, Service of Infectious Diseases, Geneva University Hospitals Geneva, Switzerland ; Laboratory of Bacteriology, Department of Genetic and Laboratory Medicine, Geneva University Hospitals Geneva, Switzerland
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O'Brien S, Hodgson DJ, Buckling A. Social evolution of toxic metal bioremediation in Pseudomonas aeruginosa. Proc Biol Sci 2015; 281:rspb.2014.0858. [PMID: 24898376 PMCID: PMC4071558 DOI: 10.1098/rspb.2014.0858] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bacteria are often iron-limited, and hence produce extracellular iron-scavenging siderophores. A crucial feature of siderophore production is that it can be an altruistic behaviour (individually costly but benefitting neighbouring cells), thus siderophore producers can be invaded by non-producing social 'cheats'. Recent studies have shown that siderophores can also bind other heavy metals (such as Cu and Zn), but in this case siderophore chelation actually reduces metal uptake by bacteria. These complexes reduce heavy metal toxicity, hence siderophore production may contribute to toxic metal bioremediation. Here, we show that siderophore production in the context of bioremediation is also an altruistic trait and can be exploited by cheating phenotypes in the opportunistic pathogen Pseudomonas aeruginosa. Specifically, we show that in toxic copper concentrations (i) siderophore non-producers evolve de novo and reach high frequencies, and (ii) producing strains are fitter than isogenic non-producing strains in monoculture, and vice versa in co-culture. Moreover, we show that the evolutionary effect copper has on reducing siderophore production is greater than the reduction observed under iron-limited conditions. We discuss the relevance of these results to the evolution of siderophore production in natural communities and heavy metal bioremediation.
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Affiliation(s)
- Siobhán O'Brien
- Department of Biosciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - David J Hodgson
- Department of Biosciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Angus Buckling
- Department of Biosciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
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A novel Pseudomonas aeruginosa strain with an oprD mutation in relation to a nosocomial respiratory infection outbreak in an intensive care unit. J Clin Microbiol 2014; 52:4388-90. [PMID: 25297323 DOI: 10.1128/jcm.02782-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Seven imipenem-resistant Pseudomonas aeruginosa isolates were recovered from the sputum samples of pneumonia patients in southwestern China. They had identical antibiotic resistance patterns and indistinguishable pulsed-field gel electrophoresis profiles. Nucleotide sequence analysis revealed a 4-bp (AGTC) insertion in the oprD gene, resulting in a frameshift in the cognate open reading frame. These isolates became imipenem susceptible when the chromosomal oprD lesion was complemented, indicating that the 4-bp insertion in the oprD gene resulted in imipenem resistance.
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Schwartz T, Armant O, Bretschneider N, Hahn A, Kirchen S, Seifert M, Dötsch A. Whole genome and transcriptome analyses of environmental antibiotic sensitive and multi-resistant Pseudomonas aeruginosa isolates exposed to waste water and tap water. Microb Biotechnol 2014; 8:116-30. [PMID: 25186059 PMCID: PMC4321378 DOI: 10.1111/1751-7915.12156] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 07/23/2014] [Indexed: 11/29/2022] Open
Abstract
The fitness of sensitive and resistant Pseudomonas aeruginosa in different aquatic environments depends on genetic capacities and transcriptional regulation. Therefore, an antibiotic-sensitive isolate PA30 and a multi-resistant isolate PA49 originating from waste waters were compared via whole genome and transcriptome Illumina sequencing after exposure to municipal waste water and tap water. A number of different genomic islands (e.g. PAGIs, PAPIs) were identified in the two environmental isolates beside the highly conserved core genome. Exposure to tap water and waste water exhibited similar transcriptional impacts on several gene clusters (antibiotic and metal resistance, genetic mobile elements, efflux pumps) in both environmental P. aeruginosa isolates. The MexCD-OprJ efflux pump was overexpressed in PA49 in response to waste water. The expression of resistance genes, genetic mobile elements in PA49 was independent from the water matrix. Consistently, the antibiotic sensitive strain PA30 did not show any difference in expression of the intrinsic resistance determinants and genetic mobile elements. Thus, the exposure of both isolates to polluted waste water and oligotrophic tap water resulted in similar expression profiles of mentioned genes. However, changes in environmental milieus resulted in rather unspecific transcriptional responses than selected and stimuli-specific gene regulation.
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Affiliation(s)
- Thomas Schwartz
- Institute of Functional Interfaces (IFG), Campus North, Karlsruhe Institute of Technology (KIT), Hermann von Helmholtz Platz 1, Eggenstein-Leopoldshafen, D-76344, Germany
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Musafer HK, Kuchma SL, Naimie AA, Schwartzman JD, Al-Mathkhury HJF, O'Toole GA. Investigating the link between imipenem resistance and biofilm formation by Pseudomonas aeruginosa. MICROBIAL ECOLOGY 2014; 68:111-120. [PMID: 24435545 PMCID: PMC8978818 DOI: 10.1007/s00248-013-0361-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 12/23/2013] [Indexed: 06/03/2023]
Abstract
Pseudomonas aeruginosa, a ubiquitous environmental organism, is a difficult-to-treat opportunistic pathogen due to its broad-spectrum antibiotic resistance and its ability to form biofilms. In this study, we investigate the link between resistance to a clinically important antibiotic, imipenem, and biofilm formation. First, we observed that the laboratory strain P. aeruginosa PAO1 carrying a mutation in the oprD gene, which confers resistance to imipenem, showed a modest reduction in biofilm formation. We also observed an inverse relationship between imipenem resistance and biofilm formation for imipenem-resistant strains selected in vitro, as well as for clinical isolates. We identified two clinical isolates of P. aeruginosa from the sputum of cystic fibrosis patients that formed robust biofilms, but were sensitive to imipenem (MIC ≤ 2 μg/ml). To test the hypothesis that there is a general link between imipenem resistance and biofilm formation, we performed transposon mutagenesis of these two clinical strains to identify mutants defective in biofilm formation, and then tested these mutants for imipenem resistance. Analysis of the transposon mutants revealed a role for previously described biofilm factors in these clinical isolates of P. aeruginosa, including mutations in the pilY1, pilX, pilW, algC, and pslI genes, but none of the biofilm-deficient mutants became imipenem resistant (MIC ≥ 8 μg/ml), arguing against a general link between biofilm formation and resistance to imipenem. Thus, assessing biofilm formation capabilities of environmental isolates is unlikely to serve as a good predictor of imipenem resistance. We also discuss our findings in light of the limited literature addressing planktonic antibiotic resistance factors that impact biofilm formation.
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Affiliation(s)
- Hadeel K Musafer
- Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq
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Role of efflux pumps: MexAB-OprM and MexXY(-OprA), AmpC cephalosporinase and OprD porin in non-metallo-β-lactamase producing Pseudomonas aeruginosa isolated from cystic fibrosis and burn patients. INFECTION GENETICS AND EVOLUTION 2014; 24:187-92. [DOI: 10.1016/j.meegid.2014.03.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Revised: 03/09/2014] [Accepted: 03/19/2014] [Indexed: 11/21/2022]
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Art-175 is a highly efficient antibacterial against multidrug-resistant strains and persisters of Pseudomonas aeruginosa. Antimicrob Agents Chemother 2014; 58:3774-84. [PMID: 24752267 DOI: 10.1128/aac.02668-14] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Artilysins constitute a novel class of efficient enzyme-based antibacterials. Specifically, they covalently combine a bacteriophage-encoded endolysin, which degrades the peptidoglycan, with a targeting peptide that transports the endolysin through the outer membrane of Gram-negative bacteria. Art-085, as well as Art-175, its optimized homolog with increased thermostability, are each composed of the sheep myeloid 29-amino acid (SMAP-29) peptide fused to the KZ144 endolysin. In contrast to KZ144, Art-085 and Art-175 pass the outer membrane and kill Pseudomonas aeruginosa, including multidrug-resistant strains, in a rapid and efficient (∼ 5 log units) manner. Time-lapse microscopy confirms that Art-175 punctures the peptidoglycan layer within 1 min, inducing a bulging membrane and complete lysis. Art-175 is highly refractory to resistance development by naturally occurring mutations. In addition, the resistance mechanisms against 21 therapeutically used antibiotics do not show cross-resistance to Art-175. Since Art-175 does not require an active metabolism for its activity, it has a superior bactericidal effect against P. aeruginosa persisters (up to >4 log units compared to that of the untreated controls). In summary, Art-175 is a novel antibacterial that is well suited for a broad range of applications in hygiene and veterinary and human medicine, with a unique potential to target persister-driven chronic infections.
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Emergence of carbapenem resistance due to the novel insertion sequence ISPa8 in Pseudomonas aeruginosa. PLoS One 2014; 9:e91299. [PMID: 24614163 PMCID: PMC3948848 DOI: 10.1371/journal.pone.0091299] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 02/09/2014] [Indexed: 11/19/2022] Open
Abstract
Chronic lung infections due to the persistence of Pseudomonas aeruginosa in cystic fibrosis patients are typically associated with the emergence of antibiotic resistance. The purpose of this study was to investigate the mechanisms responsible for the emergence of carbapenem resistance when a clinical isolate of P. aeruginosa collected from a patient with cystic fibrosis was challenged with meropenem. Nine carbapenem-resistant mutants were selected with subinhibitory concentrations of meropenem from a clinical isolate of P. aeruginosa and characterized for carbapenem resistance. Increased carbapenem MICs were associated with the identification of the novel insertion sequence ISPa8 within oprD or its promoter region in all the mutants. The position of ISPa8 was different for each of the mutants evaluated. In addition, Southern blot analyses identified multiple copies of ISPa8 within the genomes of the mutants and their parent isolate. These data demonstrate that transposition of IS elements within the Pseudomonas genome can influence antibiotic susceptibility. Understanding the selective pressures associated with the emergence of antibiotic resistance is critical for the judicious use of antimicrobial chemotherapy and the successful treatment of bacterial infections.
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Abstract
The threat of antibacterial resistance continues to increase globally, and therapeutic options for the treatment of some serious infectious diseases are diminishing. The carbapenems are a potent class of broad-spectrum drugs, and their stability against hydrolysis by many important beta-lactamases make them an important weapon in the treatment of beta-lactamase-producing bacterial pathogens. This review focuses on four carbapenems of clinical importance in the USA: imipenem, meropenem, ertapenem and doripenem. After a historical review of carbapenem development, these four carbapenems are evaluated based on their mechanism of action, spectrum of activity, potency, pharmacodynamics, clinical pharmacokinetics, clinical profiles and toxicity issues.
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Affiliation(s)
- Philip D Lister
- Creighton University School of Medicine, Department of Medical Microbiology and Immunology, 2500 California Plaza, Omaha, NE 68178, USA.
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Sefraoui I, Berrazeg M, Drissi M, Rolain JM. Molecular epidemiology of carbapenem-resistant Pseudomonas aeruginosa clinical strains isolated from western Algeria between 2009 and 2012. Microb Drug Resist 2013; 20:156-61. [PMID: 24320688 DOI: 10.1089/mdr.2013.0161] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Infections caused by carbapenem-resistant Pseudomonas aeruginosa strains represent a major therapeutic and epidemiological problem. The aim of this study was to characterize carbapenem resistance in 89 clinical strains of P. aeruginosa isolated from three hospitals in western Algeria between October 2009 and November 2012. Minimum inhibitory concentrations (MICs) of imipenem were determined by the Etest method. Screening for metallo-β-lactamase (MβL) was performed using Etest MβL strips, and a PCR was conducted to detect carbapenemase-encoding genes. The amplification of the oprD gene followed by a sequencing reaction was performed for all strains resistant to imipenem. The clonality of 53 P. aeruginosa strains was demonstrated using multilocus sequence typing (MLST). Among the 89 isolates, 35 (39.33%) were found to be resistant to IMP (MICs ≥16 μg/ml). The blaVIM-2 gene was detected in two strains. The remaining imipenem-resistant isolates showed the presence of oprD mutations. The MLST analysis differentiated strains into various clones and the strains from the same clone had an identical sequence of the oprD gene. We report the second detection in 2010 of blaVIM-2 in Algerian P. aeruginosa strains. We also found that oprD mutations were the major determinant of high-level imipenem resistance. We demonstrate that these oprD mutations can be used as a tool to study the clonality in P. aeruginosa isolates.
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Affiliation(s)
- Imane Sefraoui
- 1 Aix-Marseille Université , Unité de Recherche en Maladies Infectieuses et Tropicales Emergentes (URMITE), UM63, CNRS 7278, IRD 198, Inserm 1095, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Marseille, France
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Zeng ZR, Wang WP, Huang M, Shi LN, Wang Y, Shao HF. Mechanisms of carbapenem resistance in cephalosporin-susceptible Pseudomonas aeruginosa in China. Diagn Microbiol Infect Dis 2013; 78:268-70. [PMID: 24359931 DOI: 10.1016/j.diagmicrobio.2013.11.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Revised: 10/17/2013] [Accepted: 11/09/2013] [Indexed: 11/25/2022]
Abstract
Twenty-nine Pseudomonas aeruginosa isolates, which are resistant to carbapenems but susceptible to ceftazidime or/and cefepime, were recovered from our hospital from July 2011 to October 2011. The results of Western blotting showed that the OprD was reduced or lost. None of the 29 clinical isolates produced carbapenemases, extended-spectrum β-lactamases, or Ambler class C β-lactamases enzymes by the modified 3-dimensional test. The sequencing of oprD for these isolates showed that there are multiple point mutations, large fragment substitutions, deletions, and insertions. It showed that the expression of oprD decreased while mexA and mexX increased by real-time reverse transcriptase-PCR. These results suggested that the loss of OprD and overexpression of mexXY-OprM and mexAB-OprM are associated with carbapenem resistance in cephalosporin-susceptible Pseudomonas aeruginosa.
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Affiliation(s)
- Zhang-Rui Zeng
- Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China
| | - Wei-Ping Wang
- Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China
| | - Mei Huang
- Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China
| | - Li-Ning Shi
- Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China
| | - Ying Wang
- Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China
| | - Hai-Feng Shao
- Laboratory of Microbiology, Institute of Clinical Laboratory Medicine, Jinling Hospital, School of Medicine, Nanjing University, Nanjing 210002, PR China.
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Fournier D, Richardot C, Müller E, Robert-Nicoud M, Llanes C, Plésiat P, Jeannot K. Complexity of resistance mechanisms to imipenem in intensive care unit strains of Pseudomonas aeruginosa. J Antimicrob Chemother 2013; 68:1772-80. [DOI: 10.1093/jac/dkt098] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Allydice-Francis K, Brown PD. Diversity of Antimicrobial Resistance and Virulence Determinants in Pseudomonas aeruginosa Associated with Fresh Vegetables. Int J Microbiol 2012; 2012:426241. [PMID: 23213336 PMCID: PMC3508576 DOI: 10.1155/2012/426241] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 10/09/2012] [Indexed: 11/18/2022] Open
Abstract
With the increased focus on healthy eating and consuming raw vegetables, this study assessed the extent of contamination of fresh vegetables by Pseudomonas aeruginosa in Jamaica and examined the antibiotic susceptibility profiles and the presence of various virulence associated determinants of P. aeruginosa. Analyses indicated that vegetables from retail markets and supermarkets were widely contaminated by P. aeruginosa; produce from markets were more frequently contaminated, but the difference was not significant. Lettuce and carrots were the most frequently contaminated vegetables, while tomatoes were the least. Pigment production (Pyoverdine, pyocyanin, pyomelanin and pyorubin), fluorescein and alginate were common in these isolates. Imipenem, gentamicin and ciprofloxacin were the most inhibitory antimicrobial agents. However, isolates were resistant or showed reduced susceptibility to ampicillin, chloramphenicol, sulphamethoxazole/trimethoprim and aztreonam, and up to 35% of the isolates were resistant to four antimicrobial agents. As many as 30% of the isolates were positive for the fpv1 gene, and 13% had multiple genes. Sixty-four percent of the isolates harboured an exoenzyme gene (exoS, exoT, exoU or exoY), and multiple exo genes were common. We conclude that P. aeruginosa is a major contaminant of fresh vegetables, which might be a source of infection for susceptible persons within the community.
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Affiliation(s)
| | - Paul D. Brown
- Biochemistry Section, Department of Basic Medical Sciences, University of the West Indies, Mona, Kingston 7, Jamaica
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Pan-β-lactam resistance development in Pseudomonas aeruginosa clinical strains: molecular mechanisms, penicillin-binding protein profiles, and binding affinities. Antimicrob Agents Chemother 2012; 56:4771-8. [PMID: 22733064 DOI: 10.1128/aac.00680-12] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We investigated the mechanisms leading to Pseudomonas aeruginosa pan-β-lactam resistance (PBLR) development during the treatment of nosocomial infections, with a particular focus on the modification of penicillin-binding protein (PBP) profiles and imipenem, ceftazidime, and ceftolozane (former CXA-101) PBP binding affinities. For this purpose, six clonally related pairs of sequential susceptible-PBLR isolates were studied. The presence of oprD, ampD, and dacB mutations was explored by PCR followed by sequencing and the expression of ampC and efflux pump genes by real-time reverse transcription-PCR. The fluorescent penicillin Bocillin FL was used to determine PBP profiles in membrane preparations from all pairs, and 50% inhibitory concentrations (IC(50)s) of ceftolozane, ceftazidime, and imipenem were analyzed in 3 of them. Although a certain increase was noted (0 to 5 2-fold dilutions), the MICs of ceftolozane were ≤4 μg/ml in all PBLR isolates. All 6 PBLR isolates lacked OprD and overexpressed ampC and one or several efflux pumps, particularly mexB and/or mexY. Additionally, 5 of them showed modified PBP profiles, including a modified pattern (n = 1) or diminished expression (n = 1) of PBP1a and a lack of PBP4 expression (n = 4), which correlated with AmpC overexpression driven by dacB mutation. Analysis of the essential PBP IC(50)s revealed significant variation of PBP1a/b binding affinities, both within each susceptible-PBLR pair and across the different pairs. Moreover, despite the absence of significant differences in gene expression or sequence, a clear tendency toward increased PBP2 (imipenem) and PBP3 (ceftazidime, ceftolozane, imipenem) IC(50)s was noted in PBLR isolates. Thus, our results suggest that in addition to AmpC, efflux pumps, and OprD, the modification of PBP patterns appears to play a role in the in vivo emergence of PBLR strains, which still conserve certain susceptibility to the new antipseudomonal cephalosporin ceftolozane.
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Alterations of OprD in carbapenem-intermediate and -susceptible strains of Pseudomonas aeruginosa isolated from patients with bacteremia in a Spanish multicenter study. Antimicrob Agents Chemother 2012; 56:1703-13. [PMID: 22290967 DOI: 10.1128/aac.05451-11] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We investigated the presence of OprD mutations in 60 strains of metallo-ß-lactamase-negative Pseudomonas aeruginosa intermediately susceptible (IS [n = 12]; MIC = 8 μg/ml) or susceptible (S [n = 48]; MICs ≤ 1 to 4 μg/ml) to imipenem and/or meropenem that were isolated from patients with bacteremia in order to evaluate their impact on carbapenem susceptibility profiles. The presence of mutations in oprD was detected by sequencing analysis. OprD expression was assessed by both outer membrane protein (OMP) analysis and real-time PCR (RT-PCR). Fourteen (23%) isolates had an OprD identical to that of PAO1, and OprD modifications were detected in 46 isolates (77%). Isolates were classified as OprD "full-length types" (T1 [n = 40, including both wild-type OprD and variants showing several polymorphisms]) and OprD "deficient types" (T2 [n = 3 for OprD frameshift mutations] and T3 [n = 17 for premature stop codons in oprD]). RT-PCR showed that 5 OprD type T1 isolates presented reduced transcription of oprD (0.1- to 0.4-fold compared to PAO1), while oprD levels increased more than 2-fold over that seen with PAO1 in 4 OprD type T1 isolates. A total of 50% of the isolates belonging to OprD "deficient types" were susceptible to both carbapenems, and 40% were susceptible to meropenem and intermediately susceptible to imipenem. Only one isolate (5%) within this group was intermediately susceptible to both carbapenems, and one (5%) was susceptible to imipenem and intermediately susceptible to meropenem. We concluded that OprD inactivating mutations in clinical isolates of P. aeruginosa are not restricted only to carbapenem-resistant isolates but are also found in isolates with imipenem or meropenem MICs of only 0.06 to 4 μg/ml.
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Li H, Luo YF, Williams BJ, Blackwell TS, Xie CM. Structure and function of OprD protein in Pseudomonas aeruginosa: from antibiotic resistance to novel therapies. Int J Med Microbiol 2012; 302:63-8. [PMID: 22226846 DOI: 10.1016/j.ijmm.2011.10.001] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2011] [Revised: 10/06/2011] [Accepted: 10/16/2011] [Indexed: 11/16/2022] Open
Abstract
Pseudomonas aeruginosa (P. aeruginosa) is a common pathogen isolated from patients with nosocomial infections. Due to its intrinsic and acquired antimicrobial resistance, limited classes of antibiotics can be used for the treatment of infection with P. aeruginosa. Of these, the carbapenems are very important; however, the occurrence of carbapenem-resistant strains is gradually increasing over time. Deficiency of the outer membrane protein OprD confers P. aeruginosa a basal level of resistance to carbapenems, especially to imipenem. Functional studies have revealed that loops 2 and 3 in the OprD protein contain the entrance and/or binding sites for imipenem. Therefore, any mutation in loop 2 and/or loop 3 that causes conformational changes could result in carbapenem resistance. OprD is also a common channel for some amino acids and peptides, and competition with carbapenems through the channel may also occur. Furthermore, OprD is a highly regulated protein at transcriptional and post-transcriptional levels by some metals, small bioactive molecules, amino acids, and efflux pump regulators. Because of its hypermutability and highly regulated properties, OprD is thought to be the most prevalent mechanism for carbapenem resistance in P. aeruginosa. Developing new strategies to combat infection with carbapenem-resistant P. aeruginosa lacking OprD is an ongoing challenge.
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Affiliation(s)
- Hui Li
- Division of Respiratory Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong 510080, China
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Horizontal gene transfer and assortative recombination within the Acinetobacter baumannii clinical population provide genetic diversity at the single carO gene, encoding a major outer membrane protein channel. J Bacteriol 2011; 193:4736-48. [PMID: 21764928 DOI: 10.1128/jb.01533-10] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We described previously the presence in Acinetobacter baumannii of a novel outer membrane (OM) protein, CarO, which functions as an L-ornithine OM channel and whose loss was concomitant with increased carbapenem resistance among clonally related nosocomial isolates of this opportunistic pathogen. Here, we describe the existence of extensive genetic diversity at the carO gene within the A. baumannii clinical population. The systematic analysis of carO sequences from A. baumannii isolates obtained from public hospitals in Argentina revealed the existence of four highly polymorphic carO variants among them. Sequence polymorphism between the different A. baumannii CarO variants was concentrated in three well-defined protein regions that superimposed mostly to predicted surface-exposed loops. Polymorphism among A. baumannii CarO variants was manifested in differential electrophoretic mobilities, antigenic properties, abilities to form stable oligomeric structures, and l-ornithine influx abilities through the A. baumannii OM under in vivo conditions. Incongruence between the phylogenies of the clinical A. baumannii isolates analyzed and those of the carO variants they harbor suggests the existence of assortative (entire-gene) carO recombinational exchange within the A. baumannii population. Exchange of carO variants possessing differential characteristics mediated by horizontal gene transfer may constitute an A. baumannii population strategy to survive radically changing environmental conditions, such as the leap from inanimate sources to human hosts and vice versa, persistence in a compromised host, and/or survival in health care facilities.
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Wu Y, Cheng A, Wang M, Zhang S, Zhu D, Jia R, Luo Q, Chen Z, Chen X. Establishment of real-time quantitative reverse transcription polymerase chain reaction assay for transcriptional analysis of duck enteritis virus UL55 gene. Virol J 2011; 8:266. [PMID: 21631934 PMCID: PMC3120788 DOI: 10.1186/1743-422x-8-266] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 06/01/2011] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Real-time quantitative reverse transcription polymerase chain reaction assay (qRT-PCR) has become the benchmark for detection and quantification of target gene expression level and been utilized increasingly in detection of viral load and therapy monitoring. The dynamic transcription variation of duck enteritis virus UL55 gene during the life cycle of duck enteritis virus in infected cells has not been reported yet. RESULTS The newly identified duck enteritis virus UL55 gene was amplified and cloned into pMD18-T vector after digestion to generate a recombinant plasmid pMD18-T/UL55 for the establishment of qRT-PCR as standard DNA. The results of agarose gel electrophoresis and melting curve analysis demonstrated the primers we designed for qRT-PCR were specific and available. We used β-actin as a reference gene for normalization and established two standard curves based on pMD18-T/UL55 and pMD18-T/β-actin successfully. Based on that, the transcriptional analysis of DEV UL55 gene was performed, and the result suggested the expression of UL55 mRNA was at a low level from 0 to 8 h post-infection(p.i.), then accumulated quickly since 12 h p.i. and peaked at 36 h p.i., it can be detected till 60 h p.i.. Nucleic acid inhibition test was carried out for analyzing a temporal regulation condition of DEV UL55 gene, result revealed that it was sensitive to ganciclovir. Synthesis procedures of DEV UL55 gene can be inhibited by ganciclovir. CONCLUSIONS The method we established in this paper can provide quantitative values reflecting the amounts of measured mRNA in samples. It's available for detection and quantification, also can be used in DEV diagnosis. The DEV UL55 gene was produced most abundantly during the late phase of replication in DEV-infected cells and the transcription of it depended on the synthesized DNA. DEV UL55 gene is a γ2 gene which occurs last and have a strict requirement for viral DNA synthesis.
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Affiliation(s)
- Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan, China
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Stenkova AM, Isaeva MP, Shubin FN, Rasskazov VA, Rakin AV. Trends of the major porin gene (ompF) evolution: insight from the genus Yersinia. PLoS One 2011; 6:e20546. [PMID: 21655186 PMCID: PMC3105102 DOI: 10.1371/journal.pone.0020546] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 05/05/2011] [Indexed: 11/18/2022] Open
Abstract
OmpF is one of the major general porins of Enterobacteriaceae that belongs to the first line of bacterial defense and interactions with the biotic as well as abiotic environments. Porins are surface exposed and their structures strongly reflect the history of multiple interactions with the environmental challenges. Unfortunately, little is known on diversity of porin genes of Enterobacteriaceae and the genus Yersinia especially. We analyzed the sequences of the ompF gene from 73 Yersinia strains covering 14 known species. The phylogenetic analysis placed most of the Yersinia strains in the same line assigned by 16S rDNA-gyrB tree. Very high congruence in the tree topologies was observed for Y. enterocolitica, Y. kristensenii, Y. ruckeri, indicating that intragenic recombination in these species had no effect on the ompF gene. A significant level of intra- and interspecies recombination was found for Y. aleksiciae, Y. intermedia and Y. mollaretii. Our analysis shows that the ompF gene of Yersinia has evolved with nonrandom mutational rate under purifying selection. However, several surface loops in the OmpF porin contain positively selected sites, which very likely reflect adaptive diversification Yersinia to their ecological niches. To our knowledge, this is a first investigation of diversity of the porin gene covering the whole genus of the family Enterobacteriaceae. This study demonstrates that recombination and positive selection both contribute to evolution of ompF, but the relative contribution of these evolutionary forces are different among Yersinia species.
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Affiliation(s)
- Anna M Stenkova
- Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of Russian Academy of Sciences, Vladivostok, Russian Federation.
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Riou M, Carbonnelle S, Avrain L, Mesaros N, Pirnay JP, Bilocq F, De Vos D, Simon A, Piérard D, Jacobs F, Dediste A, Tulkens PM, Van Bambeke F, Glupczynski Y. In vivo development of antimicrobial resistance in Pseudomonas aeruginosa strains isolated from the lower respiratory tract of Intensive Care Unit patients with nosocomial pneumonia and receiving antipseudomonal therapy. Int J Antimicrob Agents 2010; 36:513-22. [DOI: 10.1016/j.ijantimicag.2010.08.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 08/06/2010] [Accepted: 08/10/2010] [Indexed: 10/19/2022]
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Turton J, Turton S, Yearwood L, Yarde S, Kaufmann M, Pitt T. Evaluation of a nine-locus variable-number tandem-repeat scheme for typing of Pseudomonas aeruginosa. Clin Microbiol Infect 2010; 16:1111-6. [DOI: 10.1111/j.1469-0691.2009.03049.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Efflux pumps, OprD porin, AmpC beta-lactamase, and multiresistance in Pseudomonas aeruginosa isolates from cystic fibrosis patients. Antimicrob Agents Chemother 2010; 54:2219-24. [PMID: 20194693 DOI: 10.1128/aac.00816-09] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Expression of ampC, oprD, mexA, mexC, mexE, and mexX was studied in 25 Pseudomonas aeruginosa isolates from cystic fibrosis patients, including 14 isolates of the Liverpool epidemic strain. Overexpressed mexA or ampC and reduced oprD were associated with beta-lactam resistance. A specific combination of mexR, nalC, and nalD mutations occurred in 11 Liverpool strain isolates, including 7 with upregulated mexA.
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