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Wang L, Zhang X, Zhou X, Bi Y, Wang M, Guo Q, Yang F. Insertion of IS Pa1635 in IS CR1 Creates a Hybrid Promoter for blaPER-1 Resulting in Resistance to Novel β-lactam/β-lactamase Inhibitor Combinations and Cefiderocol. Antimicrob Agents Chemother 2023; 67:e0013523. [PMID: 37212660 PMCID: PMC10269150 DOI: 10.1128/aac.00135-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/13/2023] [Indexed: 05/23/2023] Open
Abstract
Eleven blaPER-1-positive Pseudomonas aeruginosa clinical isolates showed variable susceptibility to ceftazidime-avibactam (CZA). The genetic contexts of blaPER-1 were identical (ISCR1-blaPER-1-gst) except for the ST697 isolate HS204 (ISCR1-ISPa1635-blaPER-1-gst). The insertion of ISPa1635 in ISCR1 upstream of blaPER-1 created a hybrid promoter, which elevated the blaPER-1 transcription level and resulted in increased resistance to CZA, ceftolozane-tazobactam, cefepime-zidebactam, and cefiderocol. Diversity in the promoter activity of blaPER-1 partially explains the variable susceptibility to CZA in PER-producing isolates.
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Affiliation(s)
- Leilei Wang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Xuefei Zhang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
- Department of Clinical Laboratory, Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Xun Zhou
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Yingmin Bi
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Minggui Wang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Qinglan Guo
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
| | - Fan Yang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, China
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Structural Basis of PER-1-Mediated Cefiderocol Resistance and Synergistic Inhibition of PER-1 by Cefiderocol in Combination with Avibactam or Durlobactam in Acinetobacter baumannii. Antimicrob Agents Chemother 2022; 66:e0082822. [PMID: 36377939 PMCID: PMC9765288 DOI: 10.1128/aac.00828-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Cefiderocol is a novel siderophore cephalosporin that displays activity against Gram-negative bacteria. To establish cefiderocol susceptibility levels of Acinetobacter baumannii strains from China, we performed susceptibility testing and genomic analyses on 131 clinical isolates. Cefiderocol shows high activity against the strains. The production of PER-1 is the key mechanism of cefiderocol resistance. In silico studies predicted that avibactam and durlobactam could inhibit cefiderocol hydrolysis by PER-1, which was confirmed by determining cefiderocol MICs in combination with inhibitors.
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Lallement C, Pasternak C, Ploy MC, Jové T. The Role of IS CR1-Borne P OUT Promoters in the Expression of Antibiotic Resistance Genes. Front Microbiol 2018; 9:2579. [PMID: 30425694 PMCID: PMC6218425 DOI: 10.3389/fmicb.2018.02579] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/09/2018] [Indexed: 11/13/2022] Open
Abstract
The ISCR1 (Insertion sequence Common Region) element is the most widespread member of the ISCR family, and is frequently present within γ-proteobacteria that occur in clinical settings. ISCR1 is always associated with the 3'Conserved Segment (3'CS) of class 1 integrons. ISCR1 contains outward-oriented promoters POUT, that may contribute to the expression of downstream genes. In ISCR1, there are two POUT promoters named PCR1-1 and PCR1-2. We performed an in silico analysis of all publically available ISCR1 sequences and identified numerous downstream genes that mainly encode antibiotic resistance genes and that are oriented in the same direction as the POUT promoters. Here, we showed that both PCR1-1 and PCR1-2 significantly increase the expression of the downstream genes bla CTX-M-9 and dfrA19. Our data highlight the role of ISCR1 in the expression of antibiotic resistance genes, which may explain why ISCR1 is so frequent in clinical settings.
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Affiliation(s)
- Claire Lallement
- INSERM, CHU Limoges, RESINFIT, U1092, University of Limoges, Limoges, France
| | - Cécile Pasternak
- INSERM, CHU Limoges, RESINFIT, U1092, University of Limoges, Limoges, France
| | - Marie-Cécile Ploy
- INSERM, CHU Limoges, RESINFIT, U1092, University of Limoges, Limoges, France
| | - Thomas Jové
- INSERM, CHU Limoges, RESINFIT, U1092, University of Limoges, Limoges, France
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Prevalence of Integrons and Insertion Sequences in ESBL-Producing E. coli Isolated from Different Sources in Navarra, Spain. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15102308. [PMID: 30347800 PMCID: PMC6209886 DOI: 10.3390/ijerph15102308] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/11/2018] [Accepted: 10/18/2018] [Indexed: 11/17/2022]
Abstract
Mobile genetic elements play an important role in the dissemination of antibiotic resistant bacteria among human and environmental sources. Therefore, the aim of this study was to determine the occurrence and patterns of integrons and insertion sequences of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolated from different sources in Navarra, northern Spain. A total of 150 isolates coming from food products, farms and feeds, aquatic environments, and humans (healthy people and hospital inpatients), were analyzed. PCRs were applied for the study of class 1, 2, and 3 integrons (intI1, intI2, and intI3), as well as for the determination of insertion sequences (IS26, ISEcp1, ISCR1, and IS903). Results show the wide presence and dissemination of intI1 (92%), while intI3 was not detected. It is remarkable, the prevalence of intI2 among food isolates, as well as the co-existence of class 1 and class 2 (8% of isolates). The majority of isolates have two or three IS elements, with the most common being IS26 (99.4%). The genetic pattern IS26⁻ISEcp1 (related with the pathogen clone ST131) was present in the 22% of isolates (including human isolates). In addition, the combination ISEcp1⁻IS26⁻IS903⁻ISCR1 was detected in 11 isolates being, to our knowledge, the first study that describes this genetic complex. Due to the wide variability observed, no relationship was determined among these mobile genetic elements and β-lactam resistance. More investigations regarding the genetic composition of these elements are needed to understand the role of multiple types of integrons and insertion sequences on the dissemination of antimicrobial resistance genes among different environments.
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Plasmid-mediated quinolone resistance: Two decades on. Drug Resist Updat 2016; 29:13-29. [PMID: 27912841 DOI: 10.1016/j.drup.2016.09.001] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/03/2016] [Accepted: 08/29/2016] [Indexed: 11/21/2022]
Abstract
After two decades of the discovery of plasmid-mediated quinolone resistance (PMQR), three different mechanisms have been associated to this phenomenon: target protection (Qnr proteins, including several families with multiple alleles), active efflux pumps (mainly QepA and OqxAB pumps) and drug modification [AAC(6')-Ib-cr acetyltransferase]. PMQR genes are usually associated with mobile or transposable elements on plasmids, and, in the case of qnr genes, are often incorporated into sul1-type integrons. PMQR has been found in clinical and environmental isolates around the world and appears to be spreading. Although the three PMQR mechanisms alone cause only low-level resistance to quinolones, they can complement other mechanisms of chromosomal resistance to reach clinical resistance level and facilitate the selection of higher-level resistance, raising a threat to the treatment of infections by microorganisms that host these mechanisms.
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Genetic Features of MCR-1-Producing Colistin-Resistant Escherichia coli Isolates in South Africa. Antimicrob Agents Chemother 2016; 60:4394-7. [PMID: 27161623 DOI: 10.1128/aac.00444-16] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/22/2016] [Indexed: 02/03/2023] Open
Abstract
A series of colistin-resistant Escherichia coli clinical isolates was recovered from hospitalized and community patients in South Africa. Seven clonally unrelated isolates harbored the mcr-1 gene located on different plasmid backbones. Two distinct plasmids were fully sequenced, and identical 2,600-bp-long DNA sequences defining a mcr-1 cassette were identified. Promoter sequences responsible for the expression of mcr-1, deduced from the precise identification of the +1 transcription start site for mcr-1, were characterized.
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Abstract
Three mechanisms for plasmid-mediated quinolone resistance (PMQR) have been discovered since 1998. Plasmid genes qnrA, qnrB, qnrC, qnrD, qnrS, and qnrVC code for proteins of the pentapeptide repeat family that protects DNA gyrase and topoisomerase IV from quinolone inhibition. The qnr genes appear to have been acquired from chromosomal genes in aquatic bacteria, are usually associated with mobilizing or transposable elements on plasmids, and are often incorporated into sul1-type integrons. The second plasmid-mediated mechanism involves acetylation of quinolones with an appropriate amino nitrogen target by a variant of the common aminoglycoside acetyltransferase AAC(6')-Ib. The third mechanism is enhanced efflux produced by plasmid genes for pumps QepAB and OqxAB. PMQR has been found in clinical and environmental isolates around the world and appears to be spreading. The plasmid-mediated mechanisms provide only low-level resistance that by itself does not exceed the clinical breakpoint for susceptibility but nonetheless facilitates selection of higher-level resistance and makes infection by pathogens containing PMQR harder to treat.
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Jayol A, Janvier F, Guillard T, Chau F, Mérens A, Robert J, Fantin B, Berçot B, Cambau E. qnrA6genetic environment and quinolone resistance conferred onProteus mirabilis. J Antimicrob Chemother 2016; 71:903-8. [DOI: 10.1093/jac/dkv431] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/12/2015] [Indexed: 11/13/2022] Open
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Relative Strengths of Promoters Provided by Common Mobile Genetic Elements Associated with Resistance Gene Expression in Gram-Negative Bacteria. Antimicrob Agents Chemother 2015; 59:5088-91. [PMID: 26055385 DOI: 10.1128/aac.00420-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 06/05/2015] [Indexed: 01/01/2023] Open
Abstract
Comparison of green fluorescent protein expression from outward-facing promoters (POUT) of ISAba1, ISEcp1, and ISAba125 revealed approximate equivalence in strength, intermediate between PCS (strong) and PCWTGN-10 (weak) class 1 integron promoter variants, >30-fold stronger than POUT of ISCR1, and >5 times stronger than Ptac. Consistent with its usual role, PCWTGN-10 produces more mRNA from a "downstream" gfp gene transcriptionally linked to a "usual" PCWTGN-10-associated gene cassette than does POUT of ISAba1.
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Li J, Lan R, Xiong Y, Ye C, Yuan M, Liu X, Chen X, Yu D, Liu B, Lin W, Bai X, Wang Y, Sun Q, Wang Y, Zhao H, Meng Q, Chen Q, Zhao A, Xu J. Sequential isolation in a patient of Raoultella planticola and Escherichia coli bearing a novel ISCR1 element carrying blaNDM-1. PLoS One 2014; 9:e89893. [PMID: 24594606 PMCID: PMC3940617 DOI: 10.1371/journal.pone.0089893] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 01/23/2014] [Indexed: 11/30/2022] Open
Abstract
Background The gene for New Delhi metallo-β-lactamase 1 (NDM-1) has been reported to be transmitted via plasmids which are easily transferable and capable of wide distribution. We report the isolation of two NDM-1 producing strains and possible in vivo transfer of blaNDM-1 in a patient. Methods Clinical samples were collected for bacterial culture and antibiotic susceptibility testing from a patient during a 34-day hospitalization. The presence of blaNDM-1 was detected by PCR and sequencing. Plasmids of interest were sequenced. Medical records were reviewed for evidence of association between the administration of antibiotics and the acquisition of the NDM-1 resistance. Results A NDM-1 positive Raoultella planticola was isolated from blood on the ninth day of hospitalization without administration of any carbapenem antibiotics and a NDM-1 positive Escherichia coli was isolated from feces on the 29th day of hospitalization and eight days after imipenem administration. The blaNDM-1 was carried by a 280 kb plasmid pRpNDM1-1 in R. planticola and a 58 kb plasmid pEcNDM1-4 in E. coli. The two plasmids shared a 4812 bp NDM-1-ISCR1 element which was found to be excisable from the plasmid as a free form and transferrable in vitro to a NDM-1 negative plasmid from E. coli. Conclusion blaNDM-1 was embedded in an ISCR1 complex class 1 integron as a novel 4812 bp NDM-1-ISCR1 element. The element was found to be able to self excise to become a free form, which may provide a new vehicle for NDM-1 dissemination. This mechanism could greatly accelerate the spread of NDM-1 mediated broad spectrum β-lactam resistance.
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Affiliation(s)
- Juan Li
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Ruiting Lan
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Yanwen Xiong
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Changyun Ye
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Min Yuan
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Xinfeng Liu
- Gansu Provincial Center for Disease Control and Prevention, Lanzhou, Gansu Province, China
| | - Xia Chen
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Deshan Yu
- Gansu Provincial Center for Disease Control and Prevention, Lanzhou, Gansu Province, China
| | - Bin Liu
- College of Life Sciences, Nankai University, Tianjin, China
| | - Wenchao Lin
- College of Life Sciences, Nankai University, Tianjin, China
| | - Xuemei Bai
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Yan Wang
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Qiangzheng Sun
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Yiting Wang
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Hongqing Zhao
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Qiong Meng
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Qiang Chen
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Ailan Zhao
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
| | - Jianguo Xu
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, National Institute for Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China
- * E-mail:
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Galán JC, González-Candelas F, Rolain JM, Cantón R. Antibiotics as selectors and accelerators of diversity in the mechanisms of resistance: from the resistome to genetic plasticity in the β-lactamases world. Front Microbiol 2013; 4:9. [PMID: 23404545 PMCID: PMC3567504 DOI: 10.3389/fmicb.2013.00009] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Accepted: 01/09/2013] [Indexed: 11/13/2022] Open
Abstract
Antibiotics and antibiotic resistance determinants, natural molecules closely related to bacterial physiology and consistent with an ancient origin, are not only present in antibiotic-producing bacteria. Throughput sequencing technologies have revealed an unexpected reservoir of antibiotic resistance in the environment. These data suggest that co-evolution between antibiotic and antibiotic resistance genes has occurred since the beginning of time. This evolutionary race has probably been slow because of highly regulated processes and low antibiotic concentrations. Therefore to understand this global problem, a new variable must be introduced, that the antibiotic resistance is a natural event, inherent to life. However, the industrial production of natural and synthetic antibiotics has dramatically accelerated this race, selecting some of the many resistance genes present in nature and contributing to their diversification. One of the best models available to understand the biological impact of selection and diversification are β-lactamases. They constitute the most widespread mechanism of resistance, at least among pathogenic bacteria, with more than 1000 enzymes identified in the literature. In the last years, there has been growing concern about the description, spread, and diversification of β-lactamases with carbapenemase activity and AmpC-type in plasmids. Phylogenies of these enzymes help the understanding of the evolutionary forces driving their selection. Moreover, understanding the adaptive potential of β-lactamases contribute to exploration the evolutionary antagonists trajectories through the design of more efficient synthetic molecules. In this review, we attempt to analyze the antibiotic resistance problem from intrinsic and environmental resistomes to the adaptive potential of resistance genes and the driving forces involved in their diversification, in order to provide a global perspective of the resistance problem.
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Affiliation(s)
- Juan-Carlos Galán
- Servicio de Microbiología, Hospital Universitario Ramón y Cajal Madrid, Spain ; Centros de Investigación Biomédica en Red en Epidemiología y Salud Pública, Instituto Ramón y Cajal de Investigación Sanitaria Madrid, Spain ; Unidad de Resistencia a Antibióticos y Virulencia Bacteriana Asociada al Consejo Superior de Investigaciones Científicas Madrid, Spain
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Ilyina TS. Mobile ISCR elements: Structure, functions, and role in emergence, increase, and spread of blocks of bacterial multiple antibiotic resistance genes. MOLECULAR GENETICS MICROBIOLOGY AND VIROLOGY 2012. [DOI: 10.3103/s0891416812040040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Genetic and biochemical characterization of an acquired subgroup B3 metallo-β-lactamase gene, blaAIM-1, and its unique genetic context in Pseudomonas aeruginosa from Australia. Antimicrob Agents Chemother 2012; 56:6154-9. [PMID: 22985886 DOI: 10.1128/aac.05654-11] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three clinical Pseudomonas aeruginosa isolates (WCH2677, WCH2813, and WCH2837) isolated from the Women's and Children's Hospital, Adelaide, Australia, produced a metallo-β-lactamase (MBL)-positive Etest result. All isolates were PCR negative for known MBL genes. A gene bank was created, and an MBL gene, designated bla(AIM-1), was cloned and fully characterized. The encoded enzyme, AIM-1, is a group B3 MBL that has the highest level of identity to THIN-B and L1. It is chromosomal and flanked by two copies (one intact and one truncated) of an ISCR element, ISCR15. Southern hybridization studies indicated the movement of both ISCR15 and bla(AIM-1) within the three different clinical isolates. AIM-1 hydrolyzes most β-lactams, with the exception of aztreonam and, to a lesser extent, ceftazidime; however, it possesses significantly higher k(cat) values for cefepime and carbapenems than most other MBLs. AIM-1 was the first mobile group B3 enzyme detected and signals further problems for already beleaguered antimicrobial regimes to treat serious P. aeruginosa and other Gram-negative infections.
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Poirel L, Bonnin RA, Nordmann P. Genetic support and diversity of acquired extended-spectrum β-lactamases in Gram-negative rods. INFECTION GENETICS AND EVOLUTION 2012; 12:883-93. [DOI: 10.1016/j.meegid.2012.02.008] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 02/14/2012] [Accepted: 02/15/2012] [Indexed: 02/01/2023]
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Zhao WH, Hu ZQ. Epidemiology and genetics of CTX-M extended-spectrum β-lactamases in Gram-negative bacteria. Crit Rev Microbiol 2012; 39:79-101. [PMID: 22697133 PMCID: PMC4086240 DOI: 10.3109/1040841x.2012.691460] [Citation(s) in RCA: 203] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CTX-M enzymes, the plasmid-mediated cefotaximases, constitute a rapidly growing family of extended-spectrum β-lactamases (ESBLs) with significant clinical impact. CTX-Ms are found in at least 26 bacterial species, particularly in Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. At least 109 members in CTX-M family are identified and can be divided into seven clusters based on their phylogeny. CTX-M-15 and CTX-M-14 are the most dominant variants. Chromosome-encoded intrinsic cefotaximases in Kluyvera spp. are proposed to be the progenitors of CTX-Ms, while ISEcp1, ISCR1 and plasmid are closely associated with their mobilization and dissemination.
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Affiliation(s)
- Wei-Hua Zhao
- Department of Microbiology and Immunology, Showa University School of Medicine, Tokyo, Japan.
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El Salabi A, Walsh TR, Chouchani C. Extended spectrum β-lactamases, carbapenemases and mobile genetic elements responsible for antibiotics resistance in Gram-negative bacteria. Crit Rev Microbiol 2012; 39:113-22. [DOI: 10.3109/1040841x.2012.691870] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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17
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Complex Class 1 Integron Containing bla CTX-M-1 Genes Isolated from Escherichia coli: A Potentially Novel Resistant Gene-Capturing Tool Kit. Curr Microbiol 2011; 64:265-70. [DOI: 10.1007/s00284-011-0062-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 12/03/2011] [Indexed: 10/14/2022]
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Evolution of an incompatibility group IncA/C plasmid harboring blaCMY-16 and qnrA6 genes and its transfer through three clones of Providencia stuartii during a two-year outbreak in a Tunisian burn unit. Antimicrob Agents Chemother 2011; 56:1342-9. [PMID: 22155825 DOI: 10.1128/aac.05267-11] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During a 2-year period in 2005 and 2006, 64 multidrug-resistant Providencia stuartii isolates, including 58 strains from 58 patients and 6 strains obtained from the same tracheal aspirator, were collected in a burn unit of a Tunisian hospital. They divided into four antibiotypes (ATB1 to ATB4) and three SmaI pulsotypes (PsA to PsC), including 49 strains belonging to clone PsA (48 of ATB1 and 1 of ATB4), 11 strains to clone PsB (7 of ATB2 and 4 of ATB3), and 4 strains to clone PsC (ATB3). All strains, except for the PsA/ATB4 isolate, were highly resistant to broad-spectrum cephalosporins due to the production of the plasmid-mediated CMY-16 β-lactamase. In addition, the 15 strains of ATB2 and ATB3 exhibited decreased quinolone susceptibility associated with QnrA6. Most strains (ATB1 and ATB3) were gentamicin resistant, related to an AAC(6')-Ib' enzyme. All these genes were located on a conjugative plasmid belonging to the incompatibility group IncA/C(2) of 195, 175, or 100 kb. Despite differences in size and in number of resistance determinants, they derived from the same plasmid, as demonstrated by similar profiles in plasmid restriction analysis and strictly homologous sequences of repAIncA/C(2), unusual antibiotic resistance genes (e.g., aphA-6), and their genetic environments. Further investigation suggested that deletions, acquisition of the ISCR1 insertion sequence, and integron cassette mobility accounted for these variations. Thus, this outbreak was due to both the spread of three clonal strains and the dissemination of a single IncA/C(2) plasmid which underwent a remarkable evolution during the epidemic period.
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Complete sequence of broad-host-range plasmid pRIO-5 harboring the extended-spectrum-β-lactamase gene blaBES₋₁. Antimicrob Agents Chemother 2011; 56:1116-9. [PMID: 22083487 DOI: 10.1128/aac.00480-11] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Broad-host-range plasmid pRIO-5, harboring the extended-spectrum β-lactamase bla(BES-1) gene in Serratia marcescens, was fully sequenced. Analysis of the 12,957-bp sequence of this IncP6-type plasmid revealed that the bla(BES-1) gene was associated with two copies of the insertion sequence IS26. The promoter responsible for the bla(BES-1) expression was hybrid, made of a -35 box located inside the inverted repeat of IS26 and a -10 box inside a remnant of an insertion sequence.
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Group IIC intron with an unusual target of integration in Enterobacter cloacae. J Bacteriol 2011; 194:150-60. [PMID: 22020643 DOI: 10.1128/jb.05786-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A potential role of group IIC-attC introns in integron gene cassette formation, that is, the way in which they could provide the attC sequence essential for recombination, has been proposed. Group IIC introns usually target the attC site of gene cassettes and more specifically their inverse core. Here we characterized a novel group IIC intron targeting the core site of the aadA1 gene cassette attC site (aadA1-qacEΔ1 gene cassette junction) from enterobacterial isolates. Intron mobility (retrohoming) was analyzed using a two-plasmid assay performed in Escherichia coli. Intron mobility assays confirmed the mobilization-integration of the group II intron into the core site of the aadA2, bla(VIM-2), bla(CARB-2), aac(6')-Ib, dfrXVb, arr2, cmlA4, and aadB gene cassettes but not into the attI site. This mobility was dependent on maturase activity. Reverse transcriptase PCR showed that this intron was transcriptionally active, and an intermediate circular form was detected by inverse PCR. This element was linked to the bla(VEB-1) extended-spectrum β-lactamase gene in a high number of enterobacterial isolates. A phylogenetic tree showed that the identified element was located in a branch separate from group IIC-attC introns, being an IIC intron possessing the ability to integrate using the core site of the attC sites as target.
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21
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PER-7, an extended-spectrum beta-lactamase with increased activity toward broad-spectrum cephalosporins in Acinetobacter baumannii. Antimicrob Agents Chemother 2011; 55:2424-7. [PMID: 21383087 DOI: 10.1128/aac.01795-10] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acinetobacter baumannii isolate AP2 was recovered from a bronchial lavage sample of a patient hospitalized in Paris, France. A. baumannii AP2 was resistant to all β-lactams, including carbapenems, and expressed the extended-spectrum β-lactamase (ESBL) PER-7, which differs from PER-1 by 4 amino acid substitutions. Compared to PER-1, PER-7 possessed higher-level hydrolytic activities against cephalosporins and aztreonam. The blaPER-7 gene was chromosomally located and associated with a mosaic class 1 integron structure. Additionally, isolate AP2 expressed the carbapenem-hydrolyzing oxacillinase OXA-23 and the 16S RNA methylase ArmA, conferring high-level resistance to aminoglycosides.
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Naseer U, Sundsfjord A. The CTX-M Conundrum: Dissemination of Plasmids andEscherichia coliClones. Microb Drug Resist 2011; 17:83-97. [DOI: 10.1089/mdr.2010.0132] [Citation(s) in RCA: 169] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Umaer Naseer
- Research Group for Host-Microbe Interactions, Department of Medical Biology, University of Tromsø, Tromsø, Norway
| | - Arnfinn Sundsfjord
- Research Group for Host-Microbe Interactions, Department of Medical Biology, University of Tromsø, Tromsø, Norway
- Reference Centre for Detection of Antimicrobial Resistance, Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway
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Richter SN, Frasson I, Bergo C, Manganelli R, Cavallaro A, Palù G. Characterisation of qnr plasmid-mediated quinolone resistance in Enterobacteriaceae from Italy: association of the qnrB19 allele with the integron element ISCR1 in Escherichia coli. Int J Antimicrob Agents 2010; 35:578-83. [PMID: 20356715 DOI: 10.1016/j.ijantimicag.2010.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 02/03/2010] [Accepted: 02/10/2010] [Indexed: 11/30/2022]
Abstract
The spread of plasmid-mediated quinolone resistance determinants (qnr-like determinants) was evaluated in a collection of 232 ciprofloxacin-resistant or extended-spectrum beta-lactamase (ESBL)-producing enterobacterial isolates recovered between November 2007 and May 2008 at Padua University Hospital, Italy. qnr genes were mainly found in Klebsiella pneumoniae (68%) and to a lesser extent in Escherichia coli (5.1%). Among the qnrA1, qnrS1 and qnrB19 alleles found, the latter was by far the most frequent. Genetic environment analysis revealed that one qnrB19 gene in E. coli was embedded in an ISCR1 complex class 1 integron. All other qnrB19 genes were flanked by an ISEcp1C region as part of the Tn2012 transposon. qnrA1- and qnrS1-containing strains were not clonally related. Both topoisomerase II mutations and ESBL (mainly SHV-12, TEM-1 and TEM-150 types) were present in most of the qnr-positive strains. qnrB19 is extremely frequent in K. pneumoniae isolates from Italy. In addition, association of qnrB19 with the ISCR1 mobile element in E. coli suggests a broad distribution of this resistance gene in the near future.
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Affiliation(s)
- Sara N Richter
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, via Gabelli 63, 35121 Padua, Italy.
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24
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Minarini LA, Poirel L, Trevisani NA, Darini ALC, Nordmann P. Predominance of CTX-M–type extended-spectrum β-lactamase genes among enterobacterial isolates from outpatients in Brazil. Diagn Microbiol Infect Dis 2009; 65:202-6. [DOI: 10.1016/j.diagmicrobio.2009.05.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 05/29/2009] [Accepted: 05/29/2009] [Indexed: 10/20/2022]
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25
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Abstract
The expanded-spectrum beta-lactamase (ESBL) gene bla(VEB-1), identified worldwide in Enterobacteriaceae and Pseudomonas aeruginosa, is associated with either class 1 integrons or repeated elements. We report here the first association of bla(VEB-1a) with the insertion sequence ISCR2 in six Acinetobacter species isolates recovered from Argentina. That genetic structure was likely at the origin of the mobilization of this ESBL gene.
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26
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Abstract
The DNA sequences of two IncHI2 plasmids, pEC-IMP and pEC-IMPQ, from metallo-beta-lactamase-producing Enterobacter cloacae clinical isolates were determined. The two conjugative plasmids are almost identical, but pEC-IMPQ carries an additional segment containing an orf513 (ISCR1), a truncated 3' conserved sequence, and a qnrB2. Comparative analyses provide support for the proposed ISCR1-mediated gene mobilization.
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27
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Harada S, Ishii Y, Yamaguchi K. Extended-spectrum β-Lactamases: Implications for the Clinical Laboratory and Therapy. Ann Lab Med 2008; 28:401-12. [DOI: 10.3343/kjlm.2008.28.6.401] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Sohei Harada
- Department of Microbiology and Infectious Diseases, School of Medicine, Faculty of Medicine, Toho University, Tokyo, Japan
- Division of Infectious Diseases2, The University of Tokyo Hospital, Tokyo, Japan
| | - Yoshikazu Ishii
- Department of Microbiology and Infectious Diseases, School of Medicine, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Keizo Yamaguchi
- Department of Microbiology and Infectious Diseases, School of Medicine, Faculty of Medicine, Toho University, Tokyo, Japan
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28
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Bae IK, Lee YH, Jeong HJ, Hong SG, Lee SH, Jeong SH. A novel blaCTX-M-14 gene-harboring complex class 1 integron with an In4-like backbone structure from a clinical isolate of Escherichia coli. Diagn Microbiol Infect Dis 2008; 62:340-2. [DOI: 10.1016/j.diagmicrobio.2008.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 06/16/2008] [Accepted: 06/25/2008] [Indexed: 10/21/2022]
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29
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Poirel L, Naas T, Nordmann P. Genetic support of extended-spectrum β-lactamases. Clin Microbiol Infect 2008; 14 Suppl 1:75-81. [DOI: 10.1111/j.1469-0691.2007.01865.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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30
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Rodríguez-Martínez JM, Velasco C, García I, Cano ME, Martínez-Martínez L, Pascual A. Characterisation of integrons containing the plasmid-mediated quinolone resistance gene qnrA1 in Klebsiella pneumoniae. Int J Antimicrob Agents 2007; 29:705-9. [PMID: 17368003 DOI: 10.1016/j.ijantimicag.2007.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Revised: 02/01/2007] [Accepted: 02/01/2007] [Indexed: 11/28/2022]
Abstract
The aim of this study was to determine the structural relationships of qnrA1 and other resistance genes in four integrons contained in four clinical isolates of Klebsiella pneumoniae. In the four integrons, the sequences surrounding qnrA1 were similar to those described for pMG252 (accession no. AY070235). The four integrons carried a class 1 integrase gene belonging to the complex class 1 integron. Three of the strains contained an identical integron coding for resistance to beta-lactams, aminoglycosides, chloramphenicol and trimethoprim. The fourth strain contained a different integron coding for resistance to beta-lactams, aminoglycosides and chloramphenicol. Downstream of the last integron, copies of IS6100 and IS26 were present. We describe two new and different integrons containing qnrA1. These integrons code for resistance to different groups of antimicrobial agents from K. pneumoniae clinical strains isolated in the USA.
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31
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Bae IK, Lee YN, Lee WG, Lee SH, Jeong SH. Novel complex class 1 integron bearing an ISCR1 element in an Escherichia coli isolate carrying the blaCTX-M-14 gene. Antimicrob Agents Chemother 2007; 51:3017-9. [PMID: 17517851 PMCID: PMC1932499 DOI: 10.1128/aac.00279-07] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This work identifies an ISCR1-related bla(CTX-M-14) gene, which has never been reported before, from a clinical isolate of Escherichia coli. The bla(CTX-M-14) gene was preceded by an ISCR1 element that was followed by a class 1 integron containing three different insert gene cassettes, i.e., dfrA12, orfF, and aadA2.
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Affiliation(s)
- Il Kwon Bae
- Research Institute for Antimicrobial Resistance and Department of Laboratory Medicine, Kosin University College of Medicine, 34 Amnam-Dong, Suh-Gu, Busan, Republic of Korea
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32
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Rodríguez-Martínez JM, Velasco C, García I, Cano ME, Martínez-Martínez L, Pascual A. Mutant prevention concentrations of fluoroquinolones for Enterobacteriaceae expressing the plasmid-carried quinolone resistance determinant qnrA1. Antimicrob Agents Chemother 2007; 51:2236-9. [PMID: 17404007 PMCID: PMC1891403 DOI: 10.1128/aac.01444-06] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The influence of qnrA1 on the development of quinolone resistance in Enterobacteriaceae was evaluated by using the mutant prevention concentration parameter. The expression of qnrA1 considerably increased the mutant prevention concentration compared to strains without this gene. In the presence of qnrA1, mutations in gyrA and parC genes were easily selected to produce high levels of quinolone resistance.
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Affiliation(s)
- J M Rodríguez-Martínez
- Department of Microbiology, University of Seville, Sanchez Pizjuan s/n, Seville 41009, Spain.
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33
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Depardieu F, Podglajen I, Leclercq R, Collatz E, Courvalin P. Modes and modulations of antibiotic resistance gene expression. Clin Microbiol Rev 2007; 20:79-114. [PMID: 17223624 PMCID: PMC1797629 DOI: 10.1128/cmr.00015-06] [Citation(s) in RCA: 246] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Since antibiotic resistance usually affords a gain of function, there is an associated biological cost resulting in a loss of fitness of the bacterial host. Considering that antibiotic resistance is most often only transiently advantageous to bacteria, an efficient and elegant way for them to escape the lethal action of drugs is the alteration of resistance gene expression. It appears that expression of bacterial resistance to antibiotics is frequently regulated, which indicates that modulation of gene expression probably reflects a good compromise between energy saving and adjustment to a rapidly evolving environment. Modulation of gene expression can occur at the transcriptional or translational level following mutations or the movement of mobile genetic elements and may involve induction by the antibiotic. In the latter case, the antibiotic can have a triple activity: as an antibacterial agent, as an inducer of resistance to itself, and as an inducer of the dissemination of resistance determinants. We will review certain mechanisms, all reversible, that bacteria have elaborated to achieve antibiotic resistance by the fine-tuning of the expression of genetic information.
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Affiliation(s)
- Florence Depardieu
- Unité des Agents Antibactériens, Institut Pasteur, 75724 Paris Cedex 15, France
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34
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Poirel L, Nordmann P, De Champs C, Eloy C. Nosocomial spread of QnrA-mediated quinolone resistance in Enterobacter sakazakii. Int J Antimicrob Agents 2007; 29:223-4. [PMID: 17000086 DOI: 10.1016/j.ijantimicag.2006.08.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 08/09/2006] [Indexed: 11/29/2022]
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35
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Poirel L, Cattoir V, Soares A, Soussy CJ, Nordmann P. Novel Ambler class A beta-lactamase LAP-1 and its association with the plasmid-mediated quinolone resistance determinant QnrS1. Antimicrob Agents Chemother 2006; 51:631-7. [PMID: 17116662 PMCID: PMC1797722 DOI: 10.1128/aac.01082-06] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The plasmid-mediated quinolone resistance determinant QnrS1 was identified in non-clonally related Enterobacter cloacae isolates in association with a transferable narrow-spectrum beta-lactam resistance marker. Cloning experiments allowed the identification of a novel Ambler class A beta-lactamase, named LAP-1. It shares 62 and 61% amino acid identity with the most closely related beta-lactamases, TEM-1 and SHV-1, respectively. It has a narrow-spectrum hydrolysis of beta-lactams and is strongly inhibited by clavulanic acid and sulbactam and, to a lesser extent, by tazobactam. Association of the blaLAP-1 gene with the qnrS1 gene was identified in E. cloacae isolates from France and Vietnam. These genes were plasmid located and associated with similar insertion sequences but were not associated with sul1-type class 1 integrons, as opposed to the qnrA genes.
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Affiliation(s)
- Laurent Poirel
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94275 Le Kremlin-Bicêtre cedex, and Faculté de Médecine Paris-Sud, Université Paris-Sud, K.-Bicêtre, France
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36
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Cantón R, Coque TM. The CTX-M β-lactamase pandemic. Curr Opin Microbiol 2006; 9:466-75. [PMID: 16942899 DOI: 10.1016/j.mib.2006.08.011] [Citation(s) in RCA: 813] [Impact Index Per Article: 45.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Accepted: 08/18/2006] [Indexed: 10/24/2022]
Abstract
In the past decade CTX-M enzymes have become the most prevalent extended-spectrum beta-lactamases, both in nosocomial and in community settings. The insertion sequences (ISs) ISEcp1 and ISCR1 (formerly common region 1 [CR1] or orf513) appear to enable the mobilization of chromosomal beta-lactamase Kluyvera species genes, which display high homology with blaCTX-Ms. These ISs are preferentially linked to specific genes: ISEcp1 to most blaCTX-Ms, and ISCR1 to blaCTX-M-2 or blaCTX-M-9. The blaCTX-M genes embedded in class 1 integrons bearing ISCR1 are associated with different Tn402-derivatives, and often with mercury Tn21-like transposons. The blaCTX-M genes linked to ISEcp1 are often located in multidrug resistance regions containing different transposons and ISs. These structures have been located in narrow and broad host-range plasmids belonging to the same incompatibility groups as those of early antibiotic resistance plasmids. These plasmids frequently carry aminoglycoside, tetracycline, sulfonamide or fluoroquinolone resistance genes [qnr and/or aac(6')-Ib-cr], which would have facilitated the dissemination of blaCTX-M genes because of co-selection processes. In Escherichia coli, they are frequently carried in well-adapted phylogenetic groups with particular virulence-factor genotypes. Also, dissemination has been associated with different clones (CTX-M-9 or CTX-M-14 producers) or epidemic clones associated with specific enzymes such as CTX-M-15. All these events might have contributed to the current pandemic CTX-M beta-lactamase scenario.
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Affiliation(s)
- Rafael Cantón
- Servicio de Microbiología, Hospital Ramón y Cajal, 28034-Madrid, Spain
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