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Abstract
Each month, subscribers to The Formulary Monograph Service receive five to six well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to your Pharmacy and Therapeutics Committee. Subscribers also receive monthly one-page summary monographs on the agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation (DUE) is also provided each month. With a subscription, the monographs are sent to you in print and CD ROM forms and are available online. Monographs can be customized to meet the needs of your facility. Subscribers to the The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X.). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. If you would like information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The October 2005 monograph topics are ramelteon, lidocaine/tetracaine patch, dapsone gel, altrasentan, and deferasirox. The DUE is on ramelteon.
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Affiliation(s)
| | - Terri Levien
- Drug Information Pharmacist, Drug Information Center, Washington State University Spokane
| | - Danial E. Baker
- Drug Information Center and Pharmacy Practice, Washington State University Spokane, PO Box 1495, Spokane, WA 99210-1495
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Abstract
Emergence of resistance among the most important bacterial pathogens is recognized as a major public health threat affecting humans worldwide. Multidrug-resistant organisms have not only emerged in the hospital environment but are now often identified in community settings, suggesting that reservoirs of antibiotic-resistant bacteria are present outside the hospital. The bacterial response to the antibiotic "attack" is the prime example of bacterial adaptation and the pinnacle of evolution. "Survival of the fittest" is a consequence of an immense genetic plasticity of bacterial pathogens that trigger specific responses that result in mutational adaptations, acquisition of genetic material, or alteration of gene expression producing resistance to virtually all antibiotics currently available in clinical practice. Therefore, understanding the biochemical and genetic basis of resistance is of paramount importance to design strategies to curtail the emergence and spread of resistance and to devise innovative therapeutic approaches against multidrug-resistant organisms. In this chapter, we will describe in detail the major mechanisms of antibiotic resistance encountered in clinical practice, providing specific examples in relevant bacterial pathogens.
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Lyu Y, Yang X, Goswami S, Gorityala BK, Idowu T, Domalaon R, Zhanel GG, Shan A, Schweizer F. Amphiphilic Tobramycin-Lysine Conjugates Sensitize Multidrug Resistant Gram-Negative Bacteria to Rifampicin and Minocycline. J Med Chem 2017; 60:3684-3702. [PMID: 28409644 DOI: 10.1021/acs.jmedchem.6b01742] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Chromosomally encoded low membrane permeability and highly efficient efflux systems are major mechanisms by which Pseudomonas aeruginosa evades antibiotic actions. Our previous reports have shown that amphiphilic tobramycin-fluoroquinolone hybrids can enhance efficacy of fluoroquinolone antibiotics against multidrug-resistant (MDR) P. aeruginosa isolates. Herein, we report on a novel class of tobramycin-lysine conjugates containing an optimized amphiphilic tobramycin-C12 tether that sensitize Gram-negative bacteria to legacy antibiotics. Combination studies indicate the ability of these conjugates to synergize rifampicin and minocycline against MDR and extensively drug resistant (XDR) P. aeruginosa isolates and enhance efficacy of both antibiotics in the Galleria mellonella larvae in vivo infection model. Mode of action studies indicate that the amphiphilic tobramycin-lysine adjuvants enhance outer membrane cell penetration and affect the proton motive force, which energizes efflux pumps. Overall, this study provides a strategy for generating effective antibiotic adjuvants that overcome resistance of rifampicin and minocycline in MDR and XDR Gram-negative bacteria including P. aeruginosa.
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Affiliation(s)
- Yinfeng Lyu
- Institute of Animal Nutrition, Northeast Agricultural University , Harbin, Heilongjiang 150030, P.R. China.,Department of Chemistry, University of Manitoba , Winnipeg, MB R3T 2N2, Canada
| | - Xuan Yang
- Department of Chemistry, University of Manitoba , Winnipeg, MB R3T 2N2, Canada
| | - Sudeep Goswami
- Department of Chemistry, University of Manitoba , Winnipeg, MB R3T 2N2, Canada
| | | | - Temilolu Idowu
- Department of Chemistry, University of Manitoba , Winnipeg, MB R3T 2N2, Canada
| | - Ronald Domalaon
- Department of Chemistry, University of Manitoba , Winnipeg, MB R3T 2N2, Canada
| | - George G Zhanel
- Department of Medical Microbiology/Infectious Diseases, University of Manitoba , Winnipeg, MB R3T 1R9, Canada
| | - Anshan Shan
- Institute of Animal Nutrition, Northeast Agricultural University , Harbin, Heilongjiang 150030, P.R. China
| | - Frank Schweizer
- Department of Chemistry, University of Manitoba , Winnipeg, MB R3T 2N2, Canada.,Department of Medical Microbiology/Infectious Diseases, University of Manitoba , Winnipeg, MB R3T 1R9, Canada
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Mastrolia MV, Galli L, De Martino M, Chiappini E. Use of tigecycline in pediatric clinical practice. Expert Rev Anti Infect Ther 2017; 15:605-612. [PMID: 28395551 DOI: 10.1080/14787210.2017.1318064] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Tigecycline, a derivative of minocycline, is an extended-spectrum antimicrobial agent. It has a restricted approval field in children and the experience of its adoption in clinical practice is reserved for cases of challenging infections. The aim of this review was to summarize evidence regarding the use of tigecycline in infants and children, focusing on the drug's clinical efficacy data and tolerability profile. Areas covered: We have conducted a literature search of the Cochrane Library, EMBASE, and MEDLINE databases, from their inception through 5 January 2017, using the following terms: tigecycline, newborn, infant, child, pediatrics, adolescent, human, clinical trial, and case report. Articles were excluded if they were redundant or not pertinent. Bibliographies of all relevant articles were also evaluated. Seventeen publications were included: 1 pharmacokinetic study, 16 case reports. In the selected publications, the patients' mean age was 4.45 years, 38.7% of children was <3 years old and favorable clinical response was achieved in 74.2% of cases. Expert commentary: Tigecycline may be a considerable option in life-threatening infections in pediatric patients. Its administration is well tolerated and has demonstrated a good clinical response in nonbacteremic patients. However, the available clinical records are limited and more studies are needed.
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Affiliation(s)
- Maria Vincenza Mastrolia
- a Pediatric Infectious Disease Unit , Anna Meyer Children's University Hospital , Florence , Italy
| | - Luisa Galli
- a Pediatric Infectious Disease Unit , Anna Meyer Children's University Hospital , Florence , Italy
| | - Maurizio De Martino
- a Pediatric Infectious Disease Unit , Anna Meyer Children's University Hospital , Florence , Italy
| | - Elena Chiappini
- a Pediatric Infectious Disease Unit , Anna Meyer Children's University Hospital , Florence , Italy
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Determinants of Antibacterial Spectrum and Resistance Potential of the Elongation Factor G Inhibitor Argyrin B in Key Gram-Negative Pathogens. Antimicrob Agents Chemother 2017; 61:AAC.02400-16. [PMID: 28096160 DOI: 10.1128/aac.02400-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 12/24/2016] [Indexed: 11/20/2022] Open
Abstract
Argyrins are natural products with antibacterial activity against Gram-negative pathogens, such as Pseudomonas aeruginosa, Burkholderia multivorans, and Stenotrophomonas maltophilia We previously showed that argyrin B targets elongation factor G (FusA). Here, we show that argyrin B activity against P. aeruginosa PAO1 (MIC = 8 μg/ml) was not affected by deletion of the MexAB-OprM, MexXY-OprM, MexCD-OprJ, or MexEF-OprN efflux pump. However, argyrin B induced expression of MexXY, causing slight but reproducible antagonism with the MexXY substrate antibiotic ciprofloxacin. Argyrin B activity against Escherichia coli increased in a strain with nine tolC efflux pump partner genes deleted. Complementation experiments showed that argyrin was effluxed by AcrAB, AcrEF, and MdtFX. Argyrin B was inactive against Acinetobacter baumannii Differences between A. baumannii and P. aeruginosa FusA proteins at key residues for argyrin B interaction implied that natural target sequence variation impacted antibacterial activity. Consistent with this, expression of the sensitive P. aeruginosa FusA1 protein in A. baumannii conferred argyrin susceptibility, whereas resistant variants did not. Argyrin B was active against S. maltophilia (MIC = 4 μg/ml). Spontaneous resistance occurred at high frequency in the bacterium (circa 10-7), mediated by mutational inactivation of fusA1 rather than by amino acid substitutions in the target binding region. This strongly suggested that resistance occurred at high frequency through loss of the sensitive FusA1, leaving an alternate argyrin-insensitive elongation factor. Supporting this, an additional fusA-like gene (fusA2) is present in S. maltophilia that was strongly upregulated in response to mutational loss of fusA1.
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Chen Y, Hu D, Zhang Q, Liao XP, Liu YH, Sun J. Efflux Pump Overexpression Contributes to Tigecycline Heteroresistance in Salmonella enterica serovar Typhimurium. Front Cell Infect Microbiol 2017; 7:37. [PMID: 28261566 PMCID: PMC5313504 DOI: 10.3389/fcimb.2017.00037] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/31/2017] [Indexed: 01/09/2023] Open
Abstract
Bacterial heteroresistance has been identified in several combinations of bacteria and antibiotics, and it complicated the therapeutic strategies. Tigecycline is being used as one of the optimal options for the treatment of infections caused by multidrug-resistant Salmonella. This study investigated whether heterorresistance to tigecycline exists in a Salmonella enterica serovar Typhimurium strain harboring the oqxAB-bearing IncHI2 plasmid pHXY0908. MIC and population analyses were performed to evaluate population-wide susceptibility to tigecycline. The effects of efflux pumps on MIC levels were assessed using the efflux pump inhibitor Phe-Arg-β-naphthylamide, measuring intracellular tigecycline accumulation as well as mRNA levels of regulatory and efflux pump genes. DNA sequencing of regulatory regions were performed and plasmid curing from a resistant strain provided an appropriate control. Results showed that MICs of a parental strain with and without pHXY0908 as well as a plasmid-cured strain 14028/Δp52 were 0.5, 1, and 1 μg/mL, respectively. Population analysis profiling (PAP) illustrated that only the pHXY0908-containg strain was heteroresistant to tigecycline. A fraction of colonies exhibited stable profiles with 4- to 8-fold increases in MIC. The frequencies of emergence of these isolates were higher in the plasmid-containing strain pHXY0908 than either the parental or the 14028/Δp52 strain. Phe-Arg-β-naphthylamide addition restored tigecycline susceptibility of these isolates and intracellular tigecycline accumulation was reduced. Heteroresistant isolates of the strain containing pHXY0908 also had elevated expression of acrB, ramA, and oqxB. DNA sequencing identified numerous mutations in RamR that have been shown to lead to ramA overexpression. In conclusions, heteroresistance to tigecycline in Salmonella enterica serovar Typhimurium was manifested in a plasmid-bearing strain. Our results suggest that this phenotype was associated with overexpression of the AcrAB-TolC and OqxAB efflux pumps.
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Affiliation(s)
- Yi Chen
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural UniversityGuangzhou, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural UniversityGuangzhou, China
| | - Daxing Hu
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural UniversityGuangzhou, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural UniversityGuangzhou, China
| | - Qijing Zhang
- Department of Veterinary Microbiology and Preventive Medicine, Iowa State University Ames, IA, USA
| | - Xiao-Ping Liao
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural UniversityGuangzhou, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural UniversityGuangzhou, China
| | - Ya-Hong Liu
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural UniversityGuangzhou, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural UniversityGuangzhou, China
| | - Jian Sun
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural UniversityGuangzhou, China; Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, South China Agricultural UniversityGuangzhou, China
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Lee H, Roh KH, Hong SG, Shin HB, Jeong SH, Song W, Uh Y, Yong D, Lee K. In Vitro Synergistic Effects of Antimicrobial Combinations on Extensively Drug-Resistant Pseudomonas aeruginosa and Acinetobacter baumannii Isolates. Ann Lab Med 2017; 36:138-44. [PMID: 26709261 PMCID: PMC4713847 DOI: 10.3343/alm.2016.36.2.138] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 06/13/2015] [Accepted: 12/02/2015] [Indexed: 01/30/2023] Open
Abstract
Background Extensively drug-resistant (XDR) Pseudomonas aeruginosa and Acinetobacter baumannii are a threat to hospitalized patients. We evaluated the effects of antimicrobial combinations on XDR P. aeruginosa and A. baumannii isolates. Methods P. aeruginosa and A. baumannii isolates, which were resistant to all antibiotics except colistin (CL), were collected from eight hospitals in Korea. Genes encoding metallo-β-lactamases (MBLs) and OXA carbapenemases were detected by PCR in eight P. aeruginosa and 30 A. baumannii isolates. In vitro synergy of antimicrobial combinations was tested by using the checkerboard method. Results Minimum inhibitory concentrations of β-lactams, aminoglycosides, and fluoroquinolones were very high, while that of CL was low for majority of XDR P. aeruginosa and A. baumannii isolates. Antimicrobial combinations including Imipenem (IPM)-CL, ceftazidime (CAZ)-CL, and rifampin (RIF)-CL exerted only additive/indifferent effects on majority of XDR P. aeruginosa isolates. Proportions of XDR A. baumannii isolates that showed synergistic and additive/indifferent inhibition after treatment with antimicrobial combinations used are as follows: IPM-ampicillin-sulbactam (AMS), 17% and 80% isolates, respectively; IPM-rifampin (RIF), 13% and 81% isolates, respectively; IPM-CL, 13% and 87% isolates, respectively; and RIF-COL, 20% and 73% isolates, respectively. Significant proportion (19%) of XDR P. aeruginosa isolates produced MBLs, and majority (82%) of A. baumannii isolates produced either MBLs or OXA-23. Conclusions Our results suggest that combinations of IPM-AMS, IPM-RIF, IPM-CL, and RIF-CL are more useful than individual drugs for treating 13-20% of XDR A. baumannii infections.
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Affiliation(s)
- Hyukmin Lee
- Department of Laboratory Medicine, International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, Korea
| | - Kyung Ho Roh
- Seegene Institute of Life Sciences, Seoul, Korea
| | - Seong Geun Hong
- Department of Laboratory Medicine, Bundang CHA Hospital, Pochon CHA University College of Medicine, Seongnam, Korea
| | - Hee Bong Shin
- Department of Laboratory Medicine, Soonchunhyang Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea
| | - Seok Hoon Jeong
- Department of Laboratory Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Wonkeun Song
- Department of Laboratory Medicine, Gangnam Sacred Hospital, Hallym University College of Medicine, Seoul, Korea
| | - Young Uh
- Department of Laboratory Medicine, Wonju Severance Christian Hospital, Yonsei University, Wonju College of Medicine, Wonju, Korea
| | - Dongeun Yong
- Department of Laboratory Medicine, Severance Hospital Yonsei University College of Medicine, Seoul, Korea
| | - Kyungwon Lee
- Department of Laboratory Medicine, Severance Hospital Yonsei University College of Medicine, Seoul, Korea.
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58
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Tetracyclines and Chloramphenicol. Infect Dis (Lond) 2017. [DOI: 10.1016/b978-0-7020-6285-8.00146-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/05/2023] Open
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Reynolds LJ, Roberts AP, Anjum MF. Efflux in the Oral Metagenome: The Discovery of a Novel Tetracycline and Tigecycline ABC Transporter. Front Microbiol 2016; 7:1923. [PMID: 27999567 PMCID: PMC5138185 DOI: 10.3389/fmicb.2016.01923] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 11/16/2016] [Indexed: 01/07/2023] Open
Abstract
Antibiotic resistance in human bacterial pathogens and commensals is threatening our ability to treat infections and conduct common medical procedures. As novel antibiotics are discovered and marketed it is important that we understand how resistance to them may arise and know what environments may act as reservoirs for such resistance genes. In this study a tetracycline and tigecycline resistant clone was identified by screening a human saliva metagenomic library in Escherichia coli EPI300 on agar containing 5 μg/ml tetracycline. Sequencing of the DNA insert present within the tetracycline resistant clone revealed it to contain a 7,765 bp fragment harboring novel ABC half transporter genes, tetAB(60). Mutagenesis studies performed on these genes confirmed that they were responsible for the tetracycline and tigecycline resistance phenotypes. Growth studies performed using E. coli EPI300 clones that harbored either the wild type, the mutated, or none of these genes indicated that there was a fitness cost associated with presence of these genes, with the isolate harboring both genes exhibiting a significantly slower growth than control strains. Given the emergence of E. coli strains that are sensitive only to tigecycline and doxycycline it is concerning that such a resistance mechanism has been identified in the human oral cavity.
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Affiliation(s)
- Liam J Reynolds
- Department of Microbial Diseases, UCL Eastman Dental Institute, Faculty of Medical Sciences, University College LondonLondon, UK; Department of Bacteriology, Animal and Plant Health AgencyAddlestone, UK
| | - Adam P Roberts
- Department of Microbial Diseases, UCL Eastman Dental Institute, Faculty of Medical Sciences, University College London London, UK
| | - Muna F Anjum
- Department of Microbial Diseases, UCL Eastman Dental Institute, Faculty of Medical Sciences, University College LondonLondon, UK; Department of Bacteriology, Animal and Plant Health AgencyAddlestone, UK
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Active efflux in dormant bacterial cells - New insights into antibiotic persistence. Drug Resist Updat 2016; 30:7-14. [PMID: 28363336 DOI: 10.1016/j.drup.2016.11.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 10/14/2016] [Accepted: 11/02/2016] [Indexed: 01/07/2023]
Abstract
Bacterial persisters are phenotypic variants of an isogenic cell population that can survive antibiotic treatment and resume growth after the antibiotics have been removed. Cell dormancy has long been considered the principle mechanism underlying persister formation. However, dormancy alone is insufficient to explain the full range of bacterial persistence. Our recent work revealed that in addition to 'passive defense' via dormancy, persister cells employ 'active defense' via enhanced efflux activity to expel drugs. This finding suggests that persisters combine two seemingly contradictory mechanisms to tolerate antibiotic attack. Here, we review the passive and active aspects of persister formation, discuss new insights into the process, and propose new techniques that can facilitate the study of bacterial persistence.
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Khanam S, Guragain M, Lenaburg DL, Kubat R, Patrauchan MA. Calcium induces tobramycin resistance in Pseudomonas aeruginosa by regulating RND efflux pumps. Cell Calcium 2016; 61:32-43. [PMID: 28034459 DOI: 10.1016/j.ceca.2016.11.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 10/27/2016] [Accepted: 11/17/2016] [Indexed: 11/24/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic multidrug resistant pathogen causing severe chronic infections. Our previous studies showed that elevated calcium (Ca2+) enhances production of several virulence factors and plant infectivity of the pathogen. Here we show that Ca2+ increases resistance of P. aeruginosa PAO1 to tobramycin, antibiotic commonly used to treat Pseudomonas infections. LC-MS/MS-based comparative analysis of the membrane proteomes of P aeruginosa grown at elevated versus not added Ca2+, determined that the abundances of two RND (resistance-nodulation-cell division) efflux pumps, MexAB-OprM and MexVW-OprM, were increased in the presence of elevated Ca2+. Analysis of twelve transposon mutants with disrupted RND efflux pumps showed that six of them (mexB, muxC, mexY, mexJ, czcB, and mexE) contribute to Ca2+-induced tobramycin resistance. Transcriptional analyses by promoter activity and RT-qPCR showed that the expression of mexAB, muxABC, mexXY, mexJK, czcCBA, and mexVW is increased by elevated Ca2+. Disruption of mexJ, mexC, mexI, and triA significantly decreased Ca2+-induced plant infectivity of the pathogen. Earlier, our group showed that PAO1 maintains intracellular Ca2+ (Ca2+in) homeostasis, which mediates Ca2+ regulation of P. aeruginosa virulence, and identified four putative Ca2+ transporters involved in this process (Guragain et al., 2013). Here we show that three of these transporters (PA2435, PA2092, PA4614) play role in Ca2+-induced tobramycin resistance and one of them (PA2435) contributes to Ca2+ regulation of mexAB-oprM promoter activity. Furthermore, mexJ, czcB, and mexE contribute to the maintenance of Ca2+in homeostasis. This provides the first evidence that Ca2+in homeostasis mediates Ca2+ regulation of RND transport systems, which contribute to Ca2+-enhanced tobramycin resistance and plant infectivity in P. aeruginosa.
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Affiliation(s)
- Sharmily Khanam
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Manita Guragain
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Dirk L Lenaburg
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Ryan Kubat
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States
| | - Marianna A Patrauchan
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, United States.
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Osei Sekyere J, Govinden U, Bester LA, Essack SY. Colistin and tigecycline resistance in carbapenemase-producing Gram-negative bacteria: emerging resistance mechanisms and detection methods. J Appl Microbiol 2016; 121:601-17. [PMID: 27153928 DOI: 10.1111/jam.13169] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 04/13/2016] [Accepted: 05/02/2016] [Indexed: 01/31/2023]
Abstract
A literature review was undertaken to ascertain the molecular basis for tigecycline and colistin resistance mechanisms and the experimental basis for the detection and delineation of this resistance particularly in carbapenemase-producing Gram-negative bacteria. Pubmed, Google Scholar and Science Direct were searched with the keywords colistin, tigecycline, resistance mechanisms and detection methods. Trans-complementation and comparative MIC studies, mass spectrometry, chromatography, spectrofluorometry, PCR, qRT-PCR and whole genome sequencing (WGS) were commonly used to determine tigecycline and colistin resistance mechanisms, specifically modifications in the structural and regulatory efflux (acrAB, OqxAB, kpgABC adeABC-FGH-IJK, mexAB-XY-oprJM and soxS, rarA robA, ramRAB marRABC, adeLRS, mexRZ and nfxb) and lipid A (pmrHFIJFKLM, lpxA, lpxC lpxD and mgrB, pmrAB, phoPQ,) genes respectively. Mutations in the ribosomal 16S rRNA operon rrnBC, also yielded resistance to tigecycline through target site modifications. The mcr-1 gene conferring resistance to colistin was identified via WGS, trans-complementation and a murine thigh infection model studies. Common detection methods are mainly antibiotic sensitivity testing with broth microdilution while molecular identification tools are mostly PCR and WGS. Spectrofluorometry, MALDI-TOF MS, micro-array and real-time multiplex PCR hold much promise for the future as new detection tools.
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Affiliation(s)
- J Osei Sekyere
- Antimicrobial Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - U Govinden
- Antimicrobial Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - L A Bester
- Biomedical Resource Unit, School of Laboratory Medicine and Medical Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - S Y Essack
- Antimicrobial Research Unit, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa
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Current perspectives on tigecycline resistance in Enterobacteriaceae: susceptibility testing issues and mechanisms of resistance. Int J Antimicrob Agents 2016; 48:11-18. [DOI: 10.1016/j.ijantimicag.2016.04.017] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 03/31/2016] [Accepted: 04/02/2016] [Indexed: 11/23/2022]
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Prickett MH, Hauser AR, McColley SA, Cullina J, Potter E, Powers C, Jain M. Aminoglycoside resistance of Pseudomonas aeruginosa in cystic fibrosis results from convergent evolution in the mexZ gene. Thorax 2016; 72:40-47. [PMID: 27325751 DOI: 10.1136/thoraxjnl-2015-208027] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 05/10/2016] [Accepted: 05/24/2016] [Indexed: 01/17/2023]
Abstract
RATIONALE Aminoglycoside (AG) resistance of Pseudomonas aeruginosa in cystic fibrosis (CF) is associated with poorer clinical outcomes and is usually due to overexpression of the efflux pump MexXY. MexXY is regulated by mexZ, one of the most commonly mutated genes in CF P. aeruginosa isolates. Little is known about the evolutionary relationship between AG resistance, MexXY expression and mexZ mutations. OBJECTIVES To test the hypothesis that AG resistance in P. aeruginosa develops in parallel with higher MexXY expression and mexZ mutations. METHODS CF P. aeruginosa isolates were compared for chronically infected (CI) adults, CI children and children with new infection. MEASUREMENTS One P. aeruginosa isolate from each patient was analysed for mexZ mutations, mexY mRNA expression and amikacin resistance. MAIN RESULTS 56 patients with CF were enrolled: 21 children with new P. aeruginosa infection, 18 CI children and 17 CI adults. Amikacin resistance and mexY mRNA expression were higher in cohorts with longer P. aeruginosa infection. The prevalence of non-conservative mexZ mutations was 0%, 33% and 65% in children with new infection, CI children and CI adults, respectively. The same trend was seen in the ratio of non-conservative to non-synonymous mexZ mutations. Of isolates with non-conservative mexZ mutations, 59% were amikacin-resistant compared with 18% of isolates with non-synonymous mutations. The doubling rate of amikacin resistance and non-conservative mexZ mutations was approximately 5 years. CONCLUSIONS P. aeruginosa mexZ mutations undergo positive selection resulting in increased mexY mRNA expression and amikacin resistance and likely play a role in bacterial adaption in the CF lung.
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Affiliation(s)
- Michelle H Prickett
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Alan R Hauser
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Susanna A McColley
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
| | - Joanne Cullina
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
| | - Eileen Potter
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
| | - Cathy Powers
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
| | - Manu Jain
- Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
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Abstract
Tetracyclines possess many properties considered ideal for antibiotic drugs, including activity against Gram-positive and -negative pathogens, proven clinical safety, acceptable tolerability, and the availability of intravenous (IV) and oral formulations for most members of the class. As with all antibiotic classes, the antimicrobial activities of tetracyclines are subject to both class-specific and intrinsic antibiotic-resistance mechanisms. Since the discovery of the first tetracyclines more than 60 years ago, ongoing optimization of the core scaffold has produced tetracyclines in clinical use and development that are capable of thwarting many of these resistance mechanisms. New chemistry approaches have enabled the creation of synthetic derivatives with improved in vitro potency and in vivo efficacy, ensuring that the full potential of the class can be explored for use against current and emerging multidrug-resistant (MDR) pathogens, including carbapenem-resistant Enterobacteriaceae, MDR Acinetobacter species, and Pseudomonas aeruginosa.
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66
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Cerceo E, Deitelzweig SB, Sherman BM, Amin AN. Multidrug-Resistant Gram-Negative Bacterial Infections in the Hospital Setting: Overview, Implications for Clinical Practice, and Emerging Treatment Options. Microb Drug Resist 2016; 22:412-31. [PMID: 26866778 DOI: 10.1089/mdr.2015.0220] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The increasing prevalence of infections due to multidrug-resistant (MDR) gram-negative bacteria constitutes a serious threat to global public health due to the limited treatment options available and the historically slow pace of development of new antimicrobial agents. Infections due to MDR strains are associated with increased morbidity and mortality and prolonged hospitalization, which translates to a significant burden on healthcare systems. In particular, MDR strains of Enterobacteriaceae (especially Klebsiella pneumoniae and Escherichia coli), Pseudomonas aeruginosa, and Acinetobacter baumannii have emerged as particularly serious concerns. In the United States, MDR strains of these organisms have been reported from hospitals throughout the country and are not limited to a small subset of hospitals. Factors that have contributed to the persistence and spread of MDR gram-negative bacteria include the following: overuse of existing antimicrobial agents, which has led to the development of adaptive resistance mechanisms by bacteria; a lack of good antimicrobial stewardship such that use of multiple broad-spectrum agents has helped perpetuate the cycle of increasing resistance; and a lack of good infection control practices. The rising prevalence of infections due to MDR gram-negative bacteria presents a significant dilemma in selecting empiric antimicrobial therapy in seriously ill hospitalized patients. A prudent initial strategy is to initiate treatment with a broad-spectrum regimen pending the availability of microbiological results allowing for targeted or narrowing of therapy. Empiric therapy with newer agents that exhibit good activity against MDR gram-negative bacterial strains such as tigecycline, ceftolozane-tazobactam, ceftazidime-avibactam, and others in the development pipeline offer promising alternatives to existing agents.
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Affiliation(s)
- Elizabeth Cerceo
- 1 Division of Hospital Medicine, Cooper Medical School of Rowan University , Camden, New Jersey
| | - Steven B Deitelzweig
- 2 Department of Hospital Medicine, Ochsner Clinical School, Ochsner Health Center , New Orleans, Louisiana
| | | | - Alpesh N Amin
- 4 Department of Medicine, University of California , Irvine, California
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Fiedler S, Bender JK, Klare I, Halbedel S, Grohmann E, Szewzyk U, Werner G. Tigecycline resistance in clinical isolates of Enterococcus faecium is mediated by an upregulation of plasmid-encoded tetracycline determinants tet(L) and tet(M). J Antimicrob Chemother 2015; 71:871-81. [PMID: 26682961 DOI: 10.1093/jac/dkv420] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 11/05/2015] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES Tigecycline represents one of the last-line therapeutics to combat multidrug-resistant bacterial pathogens, including VRE and MRSA. The German National Reference Centre for Staphylococci and Enterococci has received 73 tigecycline-resistant Enterococcus faecium and Enterococcus faecalis isolates in recent years. The precise mechanism of how enterococci become resistant to tigecycline remains undetermined. This study documents an analysis of the role of efflux pumps in tigecycline resistance in clinical isolates of Enterococcus spp. METHODS Various tigecycline MICs were found for the different isolates analysed. Tigecycline-resistant strains were analysed with respect to genome and transcriptome differences by means of WGS and RT-qPCR. Genes of interest were cloned and expressed in Listeria monocytogenes for verification of their functionality. RESULTS Detailed comparative whole-genome analyses of three isogenic strains, showing different levels of tigecycline resistance, revealed the major facilitator superfamily (MFS) efflux pump TetL and the ribosomal protection protein TetM as possible drug resistance proteins. Subsequent RT-qPCR confirmed up-regulation of the respective genes. A correlation of gene copy number and level of MIC was inferred from further qPCR analyses. Expression of both tet(L) and tet(M) in L. monocytogenes unequivocally demonstrated the potential to increase tigecycline MICs upon acquisition of either locus. CONCLUSIONS Our results indicate that increased expression of two tetracycline resistance determinants, a tet(L)-encoded MFS pump and a tet(M)-encoded ribosomal protection protein, is capable of conferring tigecycline resistance in enterococcal clinical isolates.
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Affiliation(s)
- S Fiedler
- Division of Nosocomial Pathogens and Antibiotic Resistances, National Reference Centre for Staphylococci and Enterococci, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany
| | - J K Bender
- Division of Nosocomial Pathogens and Antibiotic Resistances, National Reference Centre for Staphylococci and Enterococci, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany
| | - I Klare
- Division of Nosocomial Pathogens and Antibiotic Resistances, National Reference Centre for Staphylococci and Enterococci, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany
| | - S Halbedel
- Division of Enteropathogenic Bacteria and Legionella, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany
| | - E Grohmann
- Department of Life Sciences and Technology, Beuth University of Applied Sciences, Berlin, Germany Division of Infectious Diseases, University Medical Centre Freiburg, Freiburg, Germany
| | - U Szewzyk
- Environmental Microbiology, Technical University Berlin, Berlin, Germany
| | - G Werner
- Division of Nosocomial Pathogens and Antibiotic Resistances, National Reference Centre for Staphylococci and Enterococci, Department of Infectious Diseases, Robert Koch Institute, Wernigerode Branch, Wernigerode, Germany
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68
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Shen F, Han Q, Xie D, Fang M, Zeng H, Deng Y. Efficacy and safety of tigecycline for the treatment of severe infectious diseases: an updated meta-analysis of RCTs. Int J Infect Dis 2015; 39:25-33. [PMID: 26283551 DOI: 10.1016/j.ijid.2015.08.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 08/04/2015] [Accepted: 08/09/2015] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVES To assess the efficacy and safety of tigecycline in comparison with other antimicrobial treatments for infectious diseases. DESIGN Databases of PubMed, Embase and the Cochrane Library were searched through Feb. 2015. The reference lists of the initially identified articles and systemic review articles were manually searched. Randomized controlled trials assessing tigecycline and other antibiotics for infectious diseases in adult patients were included. RESULTS Fifteen RCTs including 7689 cases were identified. We found that tigecycline was not as effective as the comparator agents for clinical treatment success (for the clinically evaluable population, odds ratio [OR] = 0.83, 95% confidence interval [CI] = (0.73, 0.96), P=0.01; for the clinically modified intent-to-treat (mITT) population, OR = 0.81, 95% CI = (0.72, 0.92), P=0.001). There was no significant difference in microbiological treatment success with lower eradication rate in tigecycline versus comparators (for the microbiologically evaluable population, OR = 0.94, 95% CI = (0.77, 1.16), P=0.56; for the microbiological mITT populations, OR = 0.91, 95% CI = (0.74, 1.11), P=0.35). Adverse events and all-cause mortality were more common in the tigecycline group. CONCLUSIONS Tigecycline is not as effective as other antibiotics with relatively more frequency of adverse events and higher mortality rate.
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Affiliation(s)
- Fengcai Shen
- Department of Critical Care Medicine and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, People's Republic of China; Shantou University Medical College, Shantou, Guangdong, People's Republic of China.
| | - Qianpeng Han
- Department of Critical Care Medicine and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, People's Republic of China.
| | - Di Xie
- Department of Critical Care Medicine and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, People's Republic of China.
| | - Ming Fang
- Department of Critical Care Medicine and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, People's Republic of China.
| | - Hongke Zeng
- Department of Critical Care Medicine and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, People's Republic of China.
| | - Yiyu Deng
- Department of Critical Care Medicine and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, People's Republic of China.
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69
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Induced tigecycline resistance inStreptococcus pneumoniaemutants reveals mutations in ribosomal proteins and rRNA. J Antimicrob Chemother 2015; 70:2973-80. [DOI: 10.1093/jac/dkv211] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/21/2015] [Indexed: 11/12/2022] Open
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70
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Dreier J, Ruggerone P. Interaction of antibacterial compounds with RND efflux pumps in Pseudomonas aeruginosa. Front Microbiol 2015; 6:660. [PMID: 26217310 PMCID: PMC4495556 DOI: 10.3389/fmicb.2015.00660] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 06/16/2015] [Indexed: 01/14/2023] Open
Abstract
Pseudomonas aeruginosa infections are becoming increasingly difficult to treat due to intrinsic antibiotic resistance and the propensity of this pathogen to accumulate diverse resistance mechanisms. Hyperexpression of efflux pumps of the Resistance-Nodulation-Cell Division (RND)-type multidrug efflux pumps (e.g., MexAB-OprM), chromosomally encoded by mexAB-oprM, mexCD-oprJ, mexEF-oprN, and mexXY (-oprA) is often detected in clinical isolates and contributes to worrying multi-drug resistance phenotypes. Not all antibiotics are affected to the same extent by the aforementioned RND efflux pumps. The impact of efflux on antibiotic activity varies not only between different classes of antibiotics but also between members of the same family of antibiotics. Subtle differences in physicochemical features of compound-pump and compound-solvent interactions largely determine how compounds are affected by efflux activity. The combination of different high-resolution techniques helps to gain insight into the functioning of these molecular machineries. This review discusses substrate recognition patterns based on experimental evidence and computer simulations with a focus on MexB, the pump subunit of the main RND transporter in P. aeruginosa.
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Affiliation(s)
- Jürg Dreier
- Basilea Pharmaceutica International Ltd.,Basel, Switzerland
| | - Paolo Ruggerone
- Dipartimento di Fisica, Università di Cagliari – Cittadella UniversitariaMonserrato, Italy
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71
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Case-control study of the risk factors for acquisition of Pseudomonas and Proteus species during tigecycline therapy. Antimicrob Agents Chemother 2015; 59:5830-3. [PMID: 26100705 DOI: 10.1128/aac.04865-14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Accepted: 06/15/2015] [Indexed: 11/20/2022] Open
Abstract
Tigecycline is an important agent in clinical practice because of its broad-spectrum activity. However, it has no activity against Pseudomonas or Proteus species. We conducted a case-control study to analyze risk factors for the acquisition of Pseudomonas or Proteus spp. during tigecycline therapy. Placement of suction drainage at infected wound sites, ICU stay, and neurologic disease were identified as independent risk factors for the acquisition of Pseudomonas and Proteus spp.
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72
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Li XZ, Plésiat P, Nikaido H. The challenge of efflux-mediated antibiotic resistance in Gram-negative bacteria. Clin Microbiol Rev 2015; 28:337-418. [PMID: 25788514 PMCID: PMC4402952 DOI: 10.1128/cmr.00117-14] [Citation(s) in RCA: 1005] [Impact Index Per Article: 100.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps.
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Affiliation(s)
- Xian-Zhi Li
- Human Safety Division, Veterinary Drugs Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada
| | - Patrick Plésiat
- Laboratoire de Bactériologie, Faculté de Médecine-Pharmacie, Centre Hospitalier Régional Universitaire, Université de Franche-Comté, Besançon, France
| | - Hiroshi Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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73
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Sodium nitrite blocks the activity of aminoglycosides against Pseudomonas aeruginosa biofilms. Antimicrob Agents Chemother 2015; 59:3329-34. [PMID: 25801569 DOI: 10.1128/aac.00546-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 03/17/2015] [Indexed: 12/26/2022] Open
Abstract
Sodium nitrite has broad antimicrobial activity at pH 6.5, including the ability to prevent biofilm growth by Pseudomonas aeruginosa on the surfaces of airway epithelial cells. Because of its antimicrobial activity, nitrite is being investigated as an inhaled agent for chronic P. aeruginosa airway infections in cystic fibrosis patients. However, the interaction between nitrite and commonly used aminoglycosides is unknown. This paper investigates the interaction between nitrite and tobramycin in liquid culture, abiotic biofilms, and a biotic biofilm model simulating the conditions in the cystic fibrosis airway. The addition of nitrite prevented killing by aminoglycosides in liquid culture, with dose dependence between 1.5 and 15 mM. The effect was not blocked by the nitric oxide scavenger CPTIO or dependent on efflux pump activity. Nitrite shifted the biofilm minimal bactericidal concentration (MBC-biofilm) from 256 μg/ml to >1,024 μg/ml in an abiotic biofilm model. In a biotic biofilm model, the addition of 50 mM nitrite decreased the antibiofilm activity of tobramycin by up to 1.2 log. Respiratory chain inhibition recapitulated the inhibition of aminoglycoside activity by nitrite, suggesting a potential mechanism of inhibition of energy-dependent aminoglycoside uptake. In summary, sodium nitrite induces resistance to both gentamicin and tobramycin in P. aeruginosa grown in liquid culture, as an abiotic biofilm, or as a biotic biofilm.
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74
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Blair JMA, Richmond GE, Piddock LJV. Multidrug efflux pumps in Gram-negative bacteria and their role in antibiotic resistance. Future Microbiol 2014; 9:1165-77. [DOI: 10.2217/fmb.14.66] [Citation(s) in RCA: 201] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
ABSTRACT Gram-negative bacteria express a plethora of efflux pumps that are capable of transporting structurally varied molecules, including antibiotics, out of the bacterial cell. This efflux lowers the intracellular antibiotic concentration, allowing bacteria to survive at higher antibiotic concentrations. Overexpression of some efflux pumps can cause clinically relevant levels of antibiotic resistance in Gram-negative pathogens. This review discusses the role of efflux in resistance of clinical isolates of Gram-negative bacteria, the regulatory mechanisms that control efflux pump expression, the recent advances in our understanding of efflux pump structure and how inhibition of efflux is a promising future strategy for tackling multidrug resistance in Gram-negative pathogens.
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Affiliation(s)
- Jessica MA Blair
- Antimicrobials Research Group, Institute of Microbiology & Infection, School of Immunity & Infection, College of Medical & Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Grace E Richmond
- Antimicrobials Research Group, Institute of Microbiology & Infection, School of Immunity & Infection, College of Medical & Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Laura JV Piddock
- Antimicrobials Research Group, Institute of Microbiology & Infection, School of Immunity & Infection, College of Medical & Dental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
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75
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Hua X, Chen Q, Li X, Yu Y. Global transcriptional response of Acinetobacter baumannii to a subinhibitory concentration of tigecycline. Int J Antimicrob Agents 2014; 44:337-44. [DOI: 10.1016/j.ijantimicag.2014.06.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 05/08/2014] [Accepted: 06/16/2014] [Indexed: 11/15/2022]
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76
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Purssell A, Fruci M, Mikalauskas A, Gilmour C, Poole K. EsrC, an envelope stress-regulated repressor of themexCD-oprJmultidrug efflux operon inPseudomonas aeruginosa. Environ Microbiol 2014; 17:186-98. [DOI: 10.1111/1462-2920.12602] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 08/01/2014] [Accepted: 08/10/2014] [Indexed: 11/27/2022]
Affiliation(s)
- Andrew Purssell
- Department of Biomedical and Molecular Sciences; Queen's University; Kingston ON K7L 3N6 Canada
| | - Michael Fruci
- Department of Biomedical and Molecular Sciences; Queen's University; Kingston ON K7L 3N6 Canada
| | - Alaya Mikalauskas
- Department of Biomedical and Molecular Sciences; Queen's University; Kingston ON K7L 3N6 Canada
| | - Christie Gilmour
- Department of Biomedical and Molecular Sciences; Queen's University; Kingston ON K7L 3N6 Canada
| | - Keith Poole
- Department of Biomedical and Molecular Sciences; Queen's University; Kingston ON K7L 3N6 Canada
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77
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Ratnaraja NVDV, Hawkey PM. Current challenges in treating MRSA: what are the options? Expert Rev Anti Infect Ther 2014; 6:601-18. [DOI: 10.1586/14787210.6.5.601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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78
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Zavascki AP, Carvalhaes CG, Picão RC, Gales AC. Multidrug-resistantPseudomonas aeruginosaandAcinetobacter baumannii: resistance mechanisms and implications for therapy. Expert Rev Anti Infect Ther 2014; 8:71-93. [DOI: 10.1586/eri.09.108] [Citation(s) in RCA: 203] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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79
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Zhanel GG, Karlowsky JA, Rubinstein E, Hoban DJ. Tigecycline: a novel glycylcycline antibiotic. Expert Rev Anti Infect Ther 2014; 4:9-25. [PMID: 16441206 DOI: 10.1586/14787210.4.1.9] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Tigecycline, the first-in-class glycylcycline, was developed to recapture the broad spectrum of activity of the tetracycline class and to treat patients with difficult-to-treat bacterial infections. Tigecycline's in vitro spectrum of activity encompasses aerobic, facultative and anaerobic Gram-positive and -negative bacteria, including antimicrobial-resistant bacteria such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis and Enterococcus faecium, and extended-spectrum beta-lactamase-producing Enterobacteriaceae. Clinical trials involving patients with complicated skin and skin-structure infections and complicated intra-abdominal infections, including patients infected with methicillin-resistant S. aureus, demonstrated that tigecycline was bacteriologically and clinically effective with mild-to-moderate gastrointestinal adverse events (i.e., nausea, vomiting and diarrhea) the most commonly reported. Tigecycline is a promising new broad-spectrum parenteral monotherapy for the treatment of patients with Gram-positive and -negative bacterial infections.
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Affiliation(s)
- George G Zhanel
- Department of Medical Microbiology, Faculty of Medicine, Health Sciences Centre, University of Manitoba, Winnipeg, Manitoba, Canada.
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80
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Schafer JJ, Goff DA. Establishing the role of tigecycline in an era of antimicrobial resistance. Expert Rev Anti Infect Ther 2014; 6:557-67. [DOI: 10.1586/14787210.6.5.557] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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81
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Morita Y, Tomida J, Kawamura Y. Responses of Pseudomonas aeruginosa to antimicrobials. Front Microbiol 2014; 4:422. [PMID: 24409175 PMCID: PMC3884212 DOI: 10.3389/fmicb.2013.00422] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 12/24/2013] [Indexed: 11/29/2022] Open
Abstract
Infections caused by Pseudomonas aeruginosa often are hard to treat; inappropriate chemotherapy readily selects multidrug-resistant P. aeruginosa. This organism can be exposed to a wide range of concentrations of antimicrobials during treatment; learning more about the responses of P. aeruginosa to antimicrobials is therefore important. We review here responses of the bacterium P. aeruginosa upon exposure to antimicrobials at levels below the inhibitory concentration. Carbapenems (e.g., imipenem) have been shown to induce the formation of thicker and more robust biofilms, while fluoroquinolones (e.g., ciprofloxacin) and aminoglycosides (e.g., tobramycin) have been shown to induce biofilm formation. Ciprofloxacin also has been demonstrated to enhance the frequency of mutation to carbapenem resistance. Conversely, although macrolides (e.g., azithromycin) typically are not effective against P. aeruginosa because of the pseudomonal outer-membrane impermeability and efflux, macrolides do lead to a reduction in virulence factor production. Similarly, tetracycline is not very effective against this organism, but is known to induce the type-III secretion system and consequently enhance cytotoxicity of P. aeruginosain vivo. Of special note are the effects of antibacterials and disinfectants on pseudomonal efflux systems. Sub-inhibitory concentrations of protein synthesis inhibitors (aminoglycosides, tetracycline, chloramphenicol, etc.) induce the MexXY multidrug efflux system. This response is known to be mediated by interference with the translation of the leader peptide PA5471.1, with consequent effects on expression of the PA5471 gene product. Additionally, induction of the MexCD-OprJ multidrug efflux system is observed upon exposure to sub-inhibitory concentrations of disinfectants such as chlorhexidine and benzalkonium. This response is known to be dependent upon the AlgU stress response factor. Altogether, these biological responses of P. aeruginosa provide useful clues for the improvement and optimization of chemotherapy in order to appropriately treat pseudomonal infections while minimizing the emergence of resistance.
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Affiliation(s)
- Yuji Morita
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya Japan
| | - Junko Tomida
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya Japan
| | - Yoshiaki Kawamura
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya Japan
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82
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Multiple mutations lead to MexXY-OprM-dependent aminoglycoside resistance in clinical strains of Pseudomonas aeruginosa. Antimicrob Agents Chemother 2013; 58:221-8. [PMID: 24145539 DOI: 10.1128/aac.01252-13] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Constitutive overproduction of the pump MexXY-OprM is recognized as a major cause of resistance to aminoglycosides, fluoroquinolones, and zwitterionic cephalosporins in Pseudomonas aeruginosa. In this study, 57 clonally unrelated strains recovered from non-cystic fibrosis patients were analyzed to characterize the mutations resulting in upregulation of the mexXY operon. Forty-four (77.2%) of the strains, classified as agrZ mutants were found to harbor mutations inactivating the local repressor gene (mexZ) of the mexXY operon (n = 33; 57.9%) or introducing amino acid substitutions in its product, MexZ (n = 11; 19.3%). These sequence variations, which mapped in the dimerization domain, the DNA binding domain, or the rest of the MexZ structure, mostly affected amino acid positions conserved in TetR-like regulators. The 13 remaining MexXY-OprM strains (22.8%) contained intact mexZ genes encoding wild-type MexZ proteins. Eight (14.0%) of these isolates, classified as agrW1 mutants, overexpressed the gene PA5471, which codes for the MexZ antirepressor ArmZ [corrected], with 5 strains exhibiting growth defects at 37°C and 44°C, consistent with mutations impairing ribosome activity. Interestingly, one agrW1 mutant appeared to harbor a 7-bp deletion in the coding sequence of the leader peptide, PA5471.1, involved in ribosome-dependent, translational attenuation of PA5471 expression. Finally, DNA sequencing and complementation experiments revealed that 5 (8.8%) strains, classified as agrW2 mutants, harbored single amino acid variations in the sensor histidine kinase of ParRS, a two-component system known to positively control mexXY expression. Collectively, these results demonstrate that clinical strains of P. aeruginosa exploit different regulatory circuitries to mutationally overproduce the MexXY-OprM pump and become multidrug resistant, which accounts for the high prevalence of MexXY-OprM mutants in the clinical setting.
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83
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Purssell A, Poole K. Functional characterization of the NfxB repressor of the mexCD–oprJ multidrug efflux operon of Pseudomonas aeruginosa. Microbiology (Reading) 2013; 159:2058-2073. [DOI: 10.1099/mic.0.069286-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Andrew Purssell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Keith Poole
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
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84
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Linkevicius M, Sandegren L, Andersson DI. Mechanisms and fitness costs of tigecycline resistance in Escherichia coli. J Antimicrob Chemother 2013; 68:2809-19. [DOI: 10.1093/jac/dkt263] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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85
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Korth-Bradley JM, McGovern PC, Salageanu J, Matschke K, Plotka A, Pawlak S. Tigecycline does not prolong corrected QT intervals in healthy subjects. Antimicrob Agents Chemother 2013; 57:1895-901. [PMID: 23403419 PMCID: PMC3623319 DOI: 10.1128/aac.01576-12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 01/31/2013] [Indexed: 11/20/2022] Open
Abstract
We evaluated the effect of tigecycline (50-mg and 200-mg doses) on corrected QT (QTc) intervals and assessed safety and tolerability in a randomized, placebo-controlled, four-period crossover study of 48 (44 male) healthy volunteers aged 22 to 53 years. Fed subjects received tigecycline (50 mg or 200 mg) or placebo in a blinded fashion or an open-label oral dose of moxifloxacin (400 mg) after 1 liter of intravenous fluid. Serial electrocardiograms were recorded before, and for 96 h after, dosing. Blood samples for tigecycline pharmacokinetics were collected after each recording. QTc intervals were corrected using Fridericia's correction (QTcF). Pharmacokinetic parameters were calculated using noncompartmental methods with potential relationships examined using linear mixed-effects modeling. Adverse events were recorded. The upper limits of the 90% confidence interval for the mean difference between both tigecycline doses and placebo for all time-matched QTcF interval changes from baseline were <5 ms. The tigecycline concentrations initially declined rapidly and then more slowly. In the group given 50 mg of tigecycline, the pharmacokinetic parameters and means were as follows: maximum concentration of drug in serum (C(max)), 432 ng/ml; area under the concentration-time curve from time zero extrapolated to infinity (AUC0-∞), 2,366 ng · h/ml; clearance (CL), 21.1 liters/h; volume of distribution at steady state (V(ss)), 610 liters; and terminal half-life (t(1/2)), 22.1 h. Proportional or similar values were found for the group given 200 mg of tigecycline. Linear mixed-effects modeling failed to show an effect on QTcF values by tigecycline concentrations (P = 0.755). Tigecycline does not prolong the QTc interval in healthy subjects. This study has been registered at ClinicalTrials.gov under registration no. NCT01287793.
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Affiliation(s)
| | | | | | | | - Anna Plotka
- Pfizer Inc., Collegeville, Pennsylvania, USA
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86
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Beceiro A, Tomás M, Bou G. Antimicrobial resistance and virulence: a successful or deleterious association in the bacterial world? Clin Microbiol Rev 2013; 26:185-230. [PMID: 23554414 PMCID: PMC3623377 DOI: 10.1128/cmr.00059-12] [Citation(s) in RCA: 676] [Impact Index Per Article: 56.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Hosts and bacteria have coevolved over millions of years, during which pathogenic bacteria have modified their virulence mechanisms to adapt to host defense systems. Although the spread of pathogens has been hindered by the discovery and widespread use of antimicrobial agents, antimicrobial resistance has increased globally. The emergence of resistant bacteria has accelerated in recent years, mainly as a result of increased selective pressure. However, although antimicrobial resistance and bacterial virulence have developed on different timescales, they share some common characteristics. This review considers how bacterial virulence and fitness are affected by antibiotic resistance and also how the relationship between virulence and resistance is affected by different genetic mechanisms (e.g., coselection and compensatory mutations) and by the most prevalent global responses. The interplay between these factors and the associated biological costs depend on four main factors: the bacterial species involved, virulence and resistance mechanisms, the ecological niche, and the host. The development of new strategies involving new antimicrobials or nonantimicrobial compounds and of novel diagnostic methods that focus on high-risk clones and rapid tests to detect virulence markers may help to resolve the increasing problem of the association between virulence and resistance, which is becoming more beneficial for pathogenic bacteria.
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Affiliation(s)
- Alejandro Beceiro
- Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña-INIBIC, A Coruña, Spain
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87
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Cox G, Wright GD. Intrinsic antibiotic resistance: mechanisms, origins, challenges and solutions. Int J Med Microbiol 2013; 303:287-92. [PMID: 23499305 DOI: 10.1016/j.ijmm.2013.02.009] [Citation(s) in RCA: 378] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The intrinsic antibiotic resistome is a naturally occurring phenomenon that predates antibiotic chemotherapy and is present in all bacterial species. In addition to the intrinsic resistance mediated by the bacterial outer membrane and active efflux, studies have shown that a surprising number of additional genes and genetic loci also contribute to this phenotype. Antibiotic resistance is rife in both the clinic and the environment; novel therapeutic strategies need to be developed in order to prevent a major global clinical threat. The possibility of inhibiting elements comprising the intrinsic resistome in bacterial pathogens offers the promise for repurposing existing antibiotics against intrinsically resistant bacteria.
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Affiliation(s)
- Georgina Cox
- DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8N 4K1, Canada
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88
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Goulart CP, Mahmudi M, Crona KA, Jacobs SD, Kallmann M, Hall BG, Greene DC, Barlow M. Designing antibiotic cycling strategies by determining and understanding local adaptive landscapes. PLoS One 2013; 8:e56040. [PMID: 23418506 PMCID: PMC3572165 DOI: 10.1371/journal.pone.0056040] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 01/04/2013] [Indexed: 11/22/2022] Open
Abstract
The evolution of antibiotic resistance among bacteria threatens our continued ability to treat infectious diseases. The need for sustainable strategies to cure bacterial infections has never been greater. So far, all attempts to restore susceptibility after resistance has arisen have been unsuccessful, including restrictions on prescribing [1] and antibiotic cycling [2], [3]. Part of the problem may be that those efforts have implemented different classes of unrelated antibiotics, and relied on removal of resistance by random loss of resistance genes from bacterial populations (drift). Here, we show that alternating structurally similar antibiotics can restore susceptibility to antibiotics after resistance has evolved. We found that the resistance phenotypes conferred by variant alleles of the resistance gene encoding the TEM β-lactamase (blaTEM) varied greatly among 15 different β-lactam antibiotics. We captured those differences by characterizing complete adaptive landscapes for the resistance alleles blaTEM-50 and blaTEM-85, each of which differs from its ancestor blaTEM-1 by four mutations. We identified pathways through those landscapes where selection for increased resistance moved in a repeating cycle among a limited set of alleles as antibiotics were alternated. Our results showed that susceptibility to antibiotics can be sustainably renewed by cycling structurally similar antibiotics. We anticipate that these results may provide a conceptual framework for managing antibiotic resistance. This approach may also guide sustainable cycling of the drugs used to treat malaria and HIV.
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Affiliation(s)
- Christiane P. Goulart
- School of Natural Sciences, University of California Merced, Merced, California, United States of America
| | - Mentar Mahmudi
- School of Engineering, University of California Merced, Merced, California, United States of America
| | - Kristina A. Crona
- School of Natural Sciences, University of California Merced, Merced, California, United States of America
| | - Stephen D. Jacobs
- School of Natural Sciences, University of California Merced, Merced, California, United States of America
| | - Marcelo Kallmann
- School of Engineering, University of California Merced, Merced, California, United States of America
| | - Barry G. Hall
- Bellingham Research Institute, Bellingham, Washington, United States of America
| | - Devin C. Greene
- School of Natural Sciences, University of California Merced, Merced, California, United States of America
| | - Miriam Barlow
- School of Natural Sciences, University of California Merced, Merced, California, United States of America
- * E-mail:
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89
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Sun Y, Cai Y, Liu X, Bai N, Liang B, Wang R. The emergence of clinical resistance to tigecycline. Int J Antimicrob Agents 2013; 41:110-6. [DOI: 10.1016/j.ijantimicag.2012.09.005] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 09/07/2012] [Accepted: 09/07/2012] [Indexed: 02/09/2023]
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90
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Stein GE, Babinchak T. Tigecycline: an update. Diagn Microbiol Infect Dis 2013; 75:331-6. [PMID: 23357291 DOI: 10.1016/j.diagmicrobio.2012.12.004] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 12/10/2012] [Accepted: 12/18/2012] [Indexed: 01/05/2023]
Abstract
Tigecycline is a broad-spectrum antibiotic with activity against difficult-to-treat pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp., Acinetobacter baumannii, and Gram-negative bacterial strains that produce extended-spectrum β-lactamases. Minimal organ toxicity and lack of dosage adjustment in most patients are important considerations for tigecycline use. Tigecycline has been shown to be as effective and safe as standard antimicrobial therapy for treatment of adults with complicated intra-abdominal infections, complicated skin and skin structure infections, and community-acquired bacterial pneumonia. The clearest applications of tigecycline are for on-label indications. Whether tigecycline should be utilized as therapy for other infections including hospital-acquired infections with a high likelihood of multidrug-resistant pathogens is a complex issue that requires ongoing assessment. This article offers an updated overview of tigecycline clinical studies, current microbial resistance patterns, pharmacokinetic/pharmacodynamic investigations, and safety analyses.
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Affiliation(s)
- Gary E Stein
- Michigan State University, East Lansing, MI 48824, USA.
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91
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Morita Y, Tomida J, Kawamura Y. MexXY multidrug efflux system of Pseudomonas aeruginosa. Front Microbiol 2012; 3:408. [PMID: 23233851 PMCID: PMC3516279 DOI: 10.3389/fmicb.2012.00408] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 11/13/2012] [Indexed: 01/01/2023] Open
Abstract
Anti-pseudomonas aminoglycosides, such as amikacin and tobramycin, are used in the treatment of Pseudomonas aeruginosa infections. However, their use is linked to the development of resistance. During the last decade, the MexXY multidrug efflux system has been comprehensively studied, and numerous reports of laboratory and clinical isolates have been published. This system has been increasingly recognized as one of the primary determinants of aminoglycoside resistance in P. aeruginosa. In P. aeruginosa cystic fibrosis isolates, upregulation of the pump is considered the most common mechanism of aminoglycoside resistance. Non-fermentative Gram-negative pathogens possessing very close MexXY orthologs such as Achromobacter xylosoxidans and various Burkholderia species (e.g., Burkholderia pseudomallei and B. cepacia complexes), but not B. gladioli, are intrinsically resistant to aminoglycosides. Here, we summarize the properties (e.g., discovery, mechanism, gene expression, clinical significance) of the P. aeruginosa MexXY pump and other aminoglycoside efflux pumps such as AcrD of Escherichia coli, AmrAB-OprA of B. pseudomallei, and AdeABC of Acinetobacter baumannii. MexXY inducibility of the PA5471 gene product, which is dependent on ribosome inhibition or oxidative stress, is noteworthy. Moreover, the discovery of the cognate outer membrane component (OprA) of MexXY in the multidrug-resistant clinical isolate PA7, serotype O12 deserves special attention.
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Affiliation(s)
- Yuji Morita
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University Nagoya, Japan
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92
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Matthews P, Alpert M, Rahav G, Rill D, Zito E, Gardiner D, Pedersen R, Babinchak T, McGovern PC. A randomized trial of tigecycline versus ampicillin-sulbactam or amoxicillin-clavulanate for the treatment of complicated skin and skin structure infections. BMC Infect Dis 2012; 12:297. [PMID: 23145952 PMCID: PMC3560230 DOI: 10.1186/1471-2334-12-297] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 11/01/2012] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Complicated skin and skin structure infections (cSSSIs) frequently result in hospitalization with significant morbidity and mortality. METHODS In this phase 3b/4 parallel, randomized, open-label, comparative study, 531 subjects with cSSSI received tigecycline (100 mg initial dose, then 50 mg intravenously every 12 hrs) or ampicillin-sulbactam 1.5-3 g IV every 6 hrs or amoxicillin-clavulanate 1.2 g IV every 6-8 hrs. Vancomycin could be added at the discretion of the investigator to the comparator arm if methicillin-resistant Staphylococcus aureus (MRSA) was confirmed or suspected within 72 hrs of enrollment. The primary endpoint was clinical response in the clinically evaluable (CE) population at the test-of-cure (TOC) visit. Microbiologic response and safety were also assessed. The modified intent-to-treat (mITT) population comprised 531 subjects (tigecycline, n = 268; comparator, n = 263) and 405 were clinically evaluable (tigecycline, n = 209; comparator, n = 196). RESULTS In the CE population, 162/209 (77.5%) tigecycline-treated subjects and 152/196 (77.6%) comparator-treated subjects were clinically cured (difference 0.0; 95% confidence interval [CI]: -8.7, 8.6). The eradication rates at the subject level for the microbiologically evaluable (ME) population were 79.2% in the tigecycline treatment group and 76.8% in the comparator treatment group (difference 2.4; 95% CI: -9.6, 14.4) at the TOC assessment. Nausea, vomiting, and diarrhea rates were higher in the tigecycline group. CONCLUSIONS Tigecycline was generally safe and effective in the treatment of cSSSIs. TRIAL REGISTRATION ClinicalTrials.gov NCT00368537.
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Affiliation(s)
- Peter Matthews
- Department of Family Medicine, Department of Health, Mpumalanga, Middelburg, 1050, South Africa
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93
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Reduced expression of the rplU-rpmA ribosomal protein operon in mexXY-expressing pan-aminoglycoside-resistant mutants of pseudomonas aeruginosa. Antimicrob Agents Chemother 2012; 56:5171-9. [PMID: 22825121 DOI: 10.1128/aac.00846-12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Pan-aminoglycoside-resistant Pseudomonas aeruginosa mutants expressing the mexXY components of the aminoglycoside-accommodating MexXY-OprM multidrug efflux system but lacking mutations in the mexZ gene encoding a repressor of this efflux system and in the mexXY promoter have been reported (S. Fraud and K. Poole, Antimicrob. Agents Chemother. 55:1068-1074, 2011). Genome sequencing of one of these mutants, K2966, revealed the presence of a mutation within the predicted promoter region of the rplU-rpmA operon encoding ribosomal proteins L21 and L27, consistent with an observed 2-fold decrease in expression of this operon in the mutant relative to wild-type P. aeruginosa PAO1. Moreover, correction of the mutation restored rplU-rpmA expression and, significantly, reversed the elevated mexXY expression and pan-aminoglycoside resistance of the mutant. Reduced rplU-rpmA expression was also observed in a second mexXY-expressing pan-aminoglycoside-resistant mutant, K2968, which, however, lacked a mutation in the rplU-rpmA promoter region. Restoration of rplU-rpmA expression in the K2968 mutant following chromosomal integration of the rplU-rpmA operon derived from wild-type P. aeruginosa failed, however, to reverse the elevated mexXY expression and pan-aminoglycoside resistance of this mutant, although it did so for K2966, suggesting that the mutation impacting rplU-rpmA expression in K2968 also impacts other mexXY-related genes. Increased mexXY expression owing to reduced rplU-rpmA expression in K2966 and K2968 was dependent on PA5471, whose expression was also elevated in these mutants. Thus, mutational disruption of ribosome function, by limiting expression of ribosomal constituents, promotes recruitment of mexXY and does so via PA5471, reminiscent of mexXY induction by ribosome-disrupting antimicrobial agents. Interestingly, reduced rplU-rpmA expression was also observed in a mexXY-expressing pan-aminoglycoside-resistant clinical isolate, suggesting that ribosome-perturbing mutations have clinical relevance in the recruitment of the MexXY-OprM aminoglycoside resistance determinant.
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94
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Adawi A, Bisignano C, Genovese T, Filocamo A, Khouri-Assi C, Neville A, Feuerstein GZ, Cuzzocrea S, Neville LF. In vitro and in vivo properties of a fully human IgG1 monoclonal antibody that combats multidrug resistant Pseudomonas aeruginosa. Int J Mol Med 2012; 30:455-64. [PMID: 22735858 PMCID: PMC3573743 DOI: 10.3892/ijmm.2012.1040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 05/31/2012] [Indexed: 01/16/2023] Open
Abstract
The development of an anti-bacterial drug in the form of a monoclonal antibody (mAb) targeting an exposed virulence factor, represents an innovative therapeutic strategy. Consequently, a fully human IgG1 mAb (LST-007) targeting Pseudomonas aeruginosa (PA) flagellin type b was recombinantly expressed and characterized in vitro and in an infection model driven by a multidrug resistant (MDR) PA strain. LST-007 demonstrated a highly specific binding towards whole PA bacteria harboring flagellin type b and its recombinant counterpart, with a K(D) of 7.4x10(-10) M. In bioactivity assays, LST-007 or titers of Cmax sera derived from pharmacokinetic studies, markedly attenuated PA motility in an equipotent manner. In vivo, parenteral LST-007 (20 mg/kg) given as a single or double-dosing paradigm post-infection, afforded survival (up to 75% at Day 7) in a lethal model of pneumonia driven by the intratracheal (i.t.) instillation of an LD(80) of the MDR PA isolate. This protective effect was markedly superior to that of imipenem (30% survival at Day 7) and totally devoid with an irrelevant, human isotype mAb. These data lay credence that LST-007 may be a valuable adjunct to the limited list of anti-bacterials that can tackle MDR PA strains, thereby warranting its continued development for eventual clinical evaluation.
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Affiliation(s)
- Azmi Adawi
- Lostam BioPharmaceuticals, Nazareth, Israel
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95
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In vivo emergence of tigecycline resistance in multidrug-resistant Klebsiella pneumoniae and Escherichia coli. Antimicrob Agents Chemother 2012; 56:4516-8. [PMID: 22644031 DOI: 10.1128/aac.00234-12] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although resistance to tigecycline has been reported in surveillance studies, very few reports have described the emergence of resistance in vivo. We report two cases of patients with infections due to SHV-12-producing Klebsiella pneumoniae and K. pneumoniae carbapenemase-3 (KPC-3)-producing Escherichia coli, which developed tigecycline resistance in vivo after treatment. The reported limited experience underlines the risk of occurrence of a tigecycline MIC increase under treatment pressure.
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96
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Morita Y, Tomida J, Kawamura Y. Primary mechanisms mediating aminoglycoside resistance in the multidrug-resistant Pseudomonas aeruginosa clinical isolate PA7. MICROBIOLOGY-SGM 2012; 158:1071-1083. [PMID: 22282519 DOI: 10.1099/mic.0.054320-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The multiresistant taxonomic outlier Pseudomonas aeruginosa PA7 possesses the conserved efflux genes, mexXY; however these are linked to a unique gene encoding an outer membrane channel, dubbed oprA, that is absent in most P. aeruginosa strains. Using genetic knockouts and single copy chromosomal complementation, we showed that aminoglycoside resistance in PA7 is mediated in part by the MexXY-OprA pump, and intriguingly that MexXY in this strain can utilize either the OprA or OprM outer membrane channel, linked to the mexAB efflux genes. We also identified a small portion of the oprA gene immediately downstream of the mexY gene in PAO1, suggesting that non-PA7 P. aeruginosa strains might have possessed, but lost, the intact mexXY-oprA efflux pump locus. Consistent with this, most of a panel of serotype strains possessed the truncated oprA but the serotype O12 isolate had an intact mexXY-oprA locus, similar to PA7 and the related strain DSM 1128. We also showed that the mexZ repressor gene upstream of mexXY-oprA in PA7 is mutated, leading to overexpression of mexXY-oprA, using sequencing, homologous replacement and real-time quantitative reverse transcriptase PCR. Finally we assessed the contribution of MexXY and aminoglycoside modifying enzymes AAC together to resistance in PA7 and the AAC(6')-Iae-mediated amikacin-resistant clinical isolate IMCJ2.S1, concluding that the effect of the modifying enzymes is enhanced by functional efflux, especially in the presence of divalent cations, to develop high-level aminoglycoside resistance in P. aeruginosa.
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Affiliation(s)
- Yuji Morita
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya, Aichi 464-8650, Japan
| | - Junko Tomida
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya, Aichi 464-8650, Japan
| | - Yoshiaki Kawamura
- Department of Microbiology, School of Pharmacy, Aichi Gakuin University, Nagoya, Aichi 464-8650, Japan
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97
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McIntosh EDG. Efflux: how bacteria use pumps to control their microenvironment. Handb Exp Pharmacol 2012:153-166. [PMID: 23090601 DOI: 10.1007/978-3-642-28951-4_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Efflux pumps are a potent and clinically important cause of antibiotic resistance. The particular focus of this chapter is on the efflux pump as a target for antimicrobial therapy and the development of new antibacterials to address the efflux problem.Tigecycline is an example of how old antibiotics, in this case tetracyclines, which have become substrates for efflux pumps, can be extensively modified to restore antimicrobial activity and clinical efficacy.
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98
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Wei Q, Tarighi S, Dötsch A, Häussler S, Müsken M, Wright VJ, Cámara M, Williams P, Haenen S, Boerjan B, Bogaerts A, Vierstraete E, Verleyen P, Schoofs L, Willaert R, De Groote VN, Michiels J, Vercammen K, Crabbé A, Cornelis P. Phenotypic and genome-wide analysis of an antibiotic-resistant small colony variant (SCV) of Pseudomonas aeruginosa. PLoS One 2011; 6:e29276. [PMID: 22195037 PMCID: PMC3240657 DOI: 10.1371/journal.pone.0029276] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 11/23/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Small colony variants (SCVs) are slow-growing bacteria, which often show increased resistance to antibiotics and cause latent or recurrent infections. It is therefore important to understand the mechanisms at the basis of this phenotypic switch. METHODOLOGY/PRINCIPAL FINDINGS One SCV (termed PAO-SCV) was isolated, showing high resistance to gentamicin and to the cephalosporine cefotaxime. PAO-SCV was prone to reversion as evidenced by emergence of large colonies with a frequency of 10(-5) on media without antibiotics while it was stably maintained in presence of gentamicin. PAO-SCV showed a delayed growth, defective motility, and strongly reduced levels of the quorum sensing Pseudomonas quinolone signal (PQS). Whole genome expression analysis further suggested a multi-layered antibiotic resistance mechanism, including simultaneous over-expression of two drug efflux pumps (MexAB-OprM, MexXY-OprM), the LPS modification operon arnBCADTEF, and the PhoP-PhoQ two-component system. Conversely, the genes for the synthesis of PQS were strongly down-regulated in PAO-SCV. Finally, genomic analysis revealed the presence of mutations in phoP and phoQ genes as well as in the mexZ gene encoding a repressor of the mexXY and mexAB-oprM genes. Only one mutation occurred only in REV, at nucleotide 1020 of the tufA gene, a paralog of tufB, both encoding the elongation factor Tu, causing a change of the rarely used aspartic acid codon GAU to the more common GAC, possibly causing an increase of tufA mRNA translation. High expression of phoP and phoQ was confirmed for the SCV variant while the revertant showed expression levels reduced to wild-type levels. CONCLUSIONS By combining data coming from phenotypic, gene expression and proteome analysis, we could demonstrate that resistance to aminoglycosides in one SCV mutant is multifactorial including overexpression of efflux mechanisms, LPS modification and is accompanied by a drastic down-regulation of the Pseudomonas quinolone signal quorum sensing system.
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Affiliation(s)
- Qing Wei
- Research Group Microbiology, VIB Department of Structural Biology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Saeed Tarighi
- Research Group Microbiology, VIB Department of Structural Biology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Andreas Dötsch
- Chronic Pseudomonas Infections, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Susanne Häussler
- Chronic Pseudomonas Infections, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Twincore, Center for Experimental and Clinical Infection Research, Helmholtz Center for Infection Research and the Medical School Hannover, Hannover, Germany
| | - Mathias Müsken
- Chronic Pseudomonas Infections, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Twincore, Center for Experimental and Clinical Infection Research, Helmholtz Center for Infection Research and the Medical School Hannover, Hannover, Germany
| | - Victoria J. Wright
- School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Miguel Cámara
- School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Paul Williams
- School of Molecular Medical Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Steven Haenen
- Functional Genomics and Proteomics, Faculty of Sciences, K.U. Leuven, Leuven, Belgium
| | - Bart Boerjan
- Functional Genomics and Proteomics, Faculty of Sciences, K.U. Leuven, Leuven, Belgium
| | - Annelies Bogaerts
- Functional Genomics and Proteomics, Faculty of Sciences, K.U. Leuven, Leuven, Belgium
| | - Evy Vierstraete
- Functional Genomics and Proteomics, Faculty of Sciences, K.U. Leuven, Leuven, Belgium
| | - Peter Verleyen
- Functional Genomics and Proteomics, Faculty of Sciences, K.U. Leuven, Leuven, Belgium
| | - Liliane Schoofs
- Functional Genomics and Proteomics, Faculty of Sciences, K.U. Leuven, Leuven, Belgium
| | - Ronnie Willaert
- Structural Biology Brussels, VIB Department of Structural Biology, Vrije Universiteit Brussel, Brussels, Belgium
| | | | - Jan Michiels
- Centre of Microbial and Plant Genetics, K.U. Leuven, Heverlee, Belgium
| | - Ken Vercammen
- Research Group Microbiology, VIB Department of Structural Biology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
| | - Aurélie Crabbé
- The Biodesign Institute, Center for Infectious Diseases and Vaccinology, Arizona State University, Tempe, Arizona, United States of America
| | - Pierre Cornelis
- Research Group Microbiology, VIB Department of Structural Biology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium
- * E-mail:
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99
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Mohamed NM, Youssef AA. In VitroActivity of Tigecycline and Comparators Against Gram-Negative Bacteria Isolated from a Tertiary Hospital in Alexandria, Egypt. Microb Drug Resist 2011; 17:489-95. [DOI: 10.1089/mdr.2010.0195] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Nelly M. Mohamed
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Alaa A.F. Youssef
- Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
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Mechanisms decreasing in vitro susceptibility to the LpxC inhibitor CHIR-090 in the gram-negative pathogen Pseudomonas aeruginosa. Antimicrob Agents Chemother 2011; 56:17-27. [PMID: 22024823 DOI: 10.1128/aac.05417-11] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Testing P. aeruginosa efflux pump mutants showed that the LpxC inhibitor CHIR-090 is a substrate for MexAB-OprM, MexCD-OprJ, and MexEF-OprN. Utilizing P. aeruginosa PAO1 with a chromosomal mexC::luxCDABE fusion, luminescent mutants arose on medium containing 4 μg/ml CHIR-090, indicating upregulation of MexCD-OprJ. These mutants were less susceptible to CHIR-090 (MIC, 4 μg/ml) and had mutations in the mexCD-oprJ repressor gene nfxB. Nonluminescent mutants (MIC, 4 μg/ml) that had mutations in the mexAB-oprM regulator gene mexR were also observed. Plating the clinical isolate K2153 on 4 μg/ml CHIR-090 selected mutants with alterations in mexS (immediately upstream of mexT), which upregulates MexEF-OprN. A mutant altered in the putative1ribosomal binding site (RBS) upstream of lpxC and overexpressing LpxC was selected on a related LpxC inhibitor and exhibited reduced susceptibility to CHIR-090. Overexpression of LpxC from a plasmid reduced susceptibility to CHIR-090, and introduction of the altered RBS in this construct further increased expression of LpxC and decreased susceptibility to CHIR-090. Using a mutS (hypermutator) strain, a mutant with an altered lpxC target gene (LpxC L18V) was also selected. Purified LpxC L18V had activity similar to that of wild-type LpxC in an in vitro assay but had reduced inhibition by CHIR-090. Finally, an additional class of mutant, typified by an extreme growth defect, was identified. These mutants had mutations in fabG, indicating that alteration in fatty acid synthesis conferred resistance to LpxC inhibitors. Passaging experiments showed progressive decreases in susceptibility to CHIR-090. Therefore, P. aeruginosa can employ several strategies to reduce susceptibility to CHIR-090 in vitro.
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