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Woods RJ, Barbosa C, Koepping L, Raygoza JA, Mwangi M, Read AF. The evolution of antibiotic resistance in an incurable and ultimately fatal infection: A retrospective case study. Evol Med Public Health 2023; 11:163-173. [PMID: 37325804 PMCID: PMC10266578 DOI: 10.1093/emph/eoad012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 04/06/2023] [Indexed: 06/17/2023] Open
Abstract
Background and objectives The processes by which pathogens evolve within a host dictate the efficacy of treatment strategies designed to slow antibiotic resistance evolution and influence population-wide resistance levels. The aim of this study is to describe the underlying genetic and phenotypic changes leading to antibiotic resistance within a patient who died as resistance evolved to available antibiotics. We assess whether robust patterns of collateral sensitivity and response to combinations existed that might have been leveraged to improve therapy. Methodology We used whole-genome sequencing of nine isolates taken from this patient over 279 days of a chronic infection with Enterobacter hormaechei, and systematically measured changes in resistance against five of the most relevant drugs considered for treatment. Results The entirety of the genetic change is consistent with de novo mutations and plasmid loss events, without acquisition of foreign genetic material via horizontal gene transfer. The nine isolates fall into three genetically distinct lineages, with early evolutionary trajectories being supplanted by previously unobserved multi-step evolutionary trajectories. Importantly, although the population evolved resistance to all the antibiotics used to treat the infection, no single isolate was resistant to all antibiotics. Evidence of collateral sensitivity and response to combinations therapy revealed inconsistent patterns across this diversifying population. Conclusions Translating antibiotic resistance management strategies from theoretical and laboratory data to clinical situations, such as this, will require managing diverse population with unpredictable resistance trajectories.
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Affiliation(s)
- Robert J Woods
- Corresponding author. 2215 Fuller Rd, Ann Arbor, MI 48105, USA. Tel: +734 845-3460; E-mail:
| | - Camilo Barbosa
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Laura Koepping
- Division of Infectious Diseases, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Juan A Raygoza
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Michael Mwangi
- Machine Learning Modeling Working Group, Synopsys, Mountain View, CA, USA
| | - Andrew F Read
- Department of Biology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
- Department of Entomology, Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
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Xie L, Xu R, Zhu D, Sun J. Emerging resistance to ceftriaxone treatment owing to different ampD mutations in Enterobacter roggenkampii. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2022; 102:105301. [PMID: 35568334 DOI: 10.1016/j.meegid.2022.105301] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/08/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
OBJECTIVES The Enterobacter cloacae complex is responsible for a variety of infections in hospitalized patients and is resistant to β-lactam antibiotics owing to the expression of AmpC β-lactamase. We report emerging resistance in Enterobacter roggenkampii exposed to ceftriaxone and explore the mechanism underlying mutations responsible for this resistance. METHODS Three strains were derived from different samples from one patient (blood and liver abscess fluid). Antimicrobial susceptibility was evaluated by standard broth microdilution, while ampC expression was determined via RT-PCR. Genetic relatedness was evaluated via pulsed-field gel electrophoresis (PFGE). Species identification and comparative genome analysis were performed via genome sequencing. Mutation rate testing and selection of AmpC-derepressed mutants were conducted to explore the mutation mechanism. RESULTS E. roggenkampii F1247 was susceptible to third-generation cephalosporins (3GCs); F95 and F1057, found in blood sample on day 11 and liver abscess drainage fluid on day 25, were resistant. ampC expression was 341- and 642-fold higher in F95 and F1057, respectively, than in F1247. Three isolates were the same PFGE and sequence types (ST1778) and were highly homologous (2 and 4 core genome single nucleotide polymorphism differences). Compared to F1247, F95 possessed a 575 bp deletion, including 537 bp of ampD, whereas F1057 harbored only one amino acid mutation (Leu140Pro in ampD). The mutation rates from F1247 exposure to cefotaxime, ceftazidime, ceftriaxone, piperacillin-tazobactam, and cefepime were (1.90 ± 0.21) × 10-8, (3.18 ± 0.43) × 10-8, (2.00 ± 0.20) × 10-8, (2.92 ± 0.29) × 10-9, and zero, respectively. In vitro-selected mutations responsible for resistance were identified in ampD, ampR, and dacB. CONCLUSIONS E. roggenkampii may develop resistance in vivo and in vitro upon exposure to 3GCs and to a lesser extent to piperacillin-tazobactam. 3GCs should not be used as a monotherapy for E. roggenkampii infections. Therapy using cefepime or carbapenems may be preferred to piperacillin-tazobactam in the treatment of E. roggenkampii, especially if source control is difficult.
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Affiliation(s)
- Lianyan Xie
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Clinical Microbiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Rong Xu
- Department of Clinical Microbiology, Shanghai Center for Clinical Laboratory, Shanghai, China
| | - Dongan Zhu
- Department of Clinical Laboratory, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China.
| | - Jingyong Sun
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Clinical Microbiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Nakano R, Yamada Y, Nakano A, Suzuki Y, Saito K, Sakata R, Ogawa M, Narita K, Kuga A, Suwabe A, Yano H. The Role of nmcR, ampR, and ampD in the Regulation of the Class A Carbapenemase NmcA in Enterobacter ludwigii. Front Microbiol 2022; 12:794134. [PMID: 35095805 PMCID: PMC8790168 DOI: 10.3389/fmicb.2021.794134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 12/23/2021] [Indexed: 11/13/2022] Open
Abstract
Various carbapenemases have been identified in the Enterobacteriaceae. However, the induction and corresponding regulator genes of carbapenemase NmcA has rarely been detected in the Enterobacter cloacae complex (ECC). The NmcA-positive isolate ECC NR1491 was first detected in Japan in 2013. It was characterized and its induction system elucidated by evaluating its associated regulator genes nmcR, ampD, and ampR. The isolate was highly resistant to all β-lactams except for third generation cephalosporins (3GC). Whole-genome analysis revealed that blaNmcA was located on a novel 29-kb putatively mobile element called EludIMEX-1 inserted into the chromosome. The inducibility of β-lactamase activity by various agents was evaluated. Cefoxitin was confirmed as a strong concentration-independent β-lactamase inducer. In contrast, carbapenems induced β-lactamase in a concentration-dependent manner. All selected 3GC-mutants harboring substitutions on ampD (as ampR and nmcR were unchanged) were highly resistant to 3GC. The ampD mutant strain NR3901 presented with a 700 × increase in β-lactamase activity with or without induction. Similar upregulation was also observed for ampC and nmcA. NR1491 (pKU412) was obtained by transforming the ampR mutant (135Asn) clone plasmid whose expression increased by ∼100×. Like NR3901, it was highly resistant to 3GC. Overexpression of ampC, rather than nmcA, may have accounted for the higher MIC in NR1491. The ampR mutant repressed nmcA despite induction and it remains unclear how it stimulates nmcA transcription via induction. Future experiments should analyze the roles of nmcR mutant strains.
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Affiliation(s)
- Ryuichi Nakano
- Department of Microbiology and Infectious Diseases, Nara Medical University, Kashihara, Japan
| | - Yuki Yamada
- Division of Central Clinical Laboratory, Iwate Medical University Hospital, Yahaba, Japan
| | - Akiyo Nakano
- Department of Microbiology and Infectious Diseases, Nara Medical University, Kashihara, Japan
| | - Yuki Suzuki
- Department of Microbiology and Infectious Diseases, Nara Medical University, Kashihara, Japan
| | - Kai Saito
- Department of Microbiology and Infectious Diseases, Nara Medical University, Kashihara, Japan
| | - Ryuji Sakata
- Department of Bacteriology, BML Inc., Kawagoe, Japan
| | - Miho Ogawa
- Department of Bacteriology, BML Inc., Kawagoe, Japan
| | - Kazuya Narita
- Division of Central Clinical Laboratory, Iwate Medical University Hospital, Yahaba, Japan
| | - Akio Kuga
- Hamamatsu Pharmaceutical Association, Hamamatsu, Japan
| | - Akira Suwabe
- Department of Laboratory Medicine, Iwate Medical University School of Medicine, Yahaba, Japan
| | - Hisakazu Yano
- Department of Microbiology and Infectious Diseases, Nara Medical University, Kashihara, Japan
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Hemarajata P, Amick T, Yang S, Gregson A, Holzmeyer C, Bush K, Humphries RM. Selection of hyperproduction of AmpC and SME-1 in a carbapenem-resistant Serratia marcescens isolate during antibiotic therapy. J Antimicrob Chemother 2019; 73:1256-1262. [PMID: 29471486 DOI: 10.1093/jac/dky028] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 01/09/2018] [Indexed: 12/21/2022] Open
Abstract
Objectives Antibiotic selective pressure may result in changes to antimicrobial susceptibility throughout the course of infection, especially for organisms that harbour chromosomally encoded AmpC β-lactamases, notably Enterobacter spp., in which hyperexpression of ampC may be induced following treatment with cephalosporins. In this study, we document a case of bacteraemia caused by a blaSME-1-harbouring Serratia marcescens that subsequently developed resistance to expanded-spectrum cephalosporins, piperacillin/tazobactam and fluoroquinolones, over the course of several months of treatment with piperacillin/tazobactam and ciprofloxacin. Methods Susceptibility testing and WGS were performed on three S. marcescens isolates from the patient. β-Lactamase activity in the presence or absence of induction by imipenem was measured by nitrocefin hydrolysis assays. Expression of ampC and blaSME-1 under the same conditions was determined by real-time PCR. Results WGS demonstrated accumulation of missense and nonsense mutations in ampD associated with stable derepression of AmpC. Gene expression and β-lactamase activity of both AmpC and SME-1 were inducible in the initial susceptible isolate, but were constitutively high in the resistant isolate, in which total β-lactamase activity was increased by 128-fold. Conclusions Although development of such in vitro resistance due to selective pressure imposed by antibiotics is reportedly low in S. marcescens, our findings highlight the need to evaluate isolates on a regular basis during long-term antibiotic therapy.
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Affiliation(s)
- Peera Hemarajata
- Pathology and Laboratory Medicine, UCLA, Los Angeles, CA 90095, USA
| | - Thomas Amick
- Biotechnology Program, Indiana University, Bloomington, IN 47405, USA
| | - Shangxin Yang
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Aric Gregson
- Division of Infectious Diseases, UCLA, Los Angeles, CA 90095, USA
| | - Cameron Holzmeyer
- Biotechnology Program, Indiana University, Bloomington, IN 47405, USA
| | - Karen Bush
- Biotechnology Program, Indiana University, Bloomington, IN 47405, USA
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Outbreak of IMI-1 carbapenemase-producing colistin-resistant Enterobacter cloacae on the French island of Mayotte (Indian Ocean). Int J Antimicrob Agents 2018; 52:416-420. [PMID: 29807164 DOI: 10.1016/j.ijantimicag.2018.05.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 05/11/2018] [Accepted: 05/19/2018] [Indexed: 11/24/2022]
Abstract
The spread of carbapenemase-producing Enterobacteriaceae in the Southwest Indian Ocean islands is poorly known. Here we describe an outbreak of colistin-resistant Enterobacter cloacae harbouring blaIMI-1 in the French overseas department of Mayotte. Between October 2015 and January 2017, all isolates of imipenem-non-susceptible E. cloacae at Mayotte Medical Center and University Hospital of Reunion Island were screened for carbapenemase production. Positive isolates were typed by pulsed-field gel electrophoresis and whole-genome sequencing (WGS)-based multilocus sequence typing (MLST), and all β-lactamase genes were identified by PCR and sequencing. Resistance profiles were determined by agar diffusion and Etest. Genetic support of the blaIMI-1 gene was determined by WGS. A total of 18 E. cloacae isolates harbouring blaIMI-1 were detected in 17 patients from Mayotte. Pulsed-field gel electrophoresis (PFGE) analysis showed 16 of the 18 strains to be clonally related and belonging to ST820. Based on clinical data, this outbreak most likely had a community origin. The blaIMI-1 gene in the 18 isolates was carried by a new variant of an integrative mobile element involving the Xer recombinases, called EcloIMEX-8. The mcr-1-mcr-5 genes were absent from the collection. The isolates belonged to E. cloacae cluster XI, known to be colistin heteroresistant. Here we report the first outbreak of IMI-1-producing Enterobacteriaceae. IMI-1-producers may be underdetected in microbiology laboratories because of their unusual antimicrobial resistance profile (resistant to imipenem but with intermediate resistance to ertapenem and susceptible to extended-spectrum cephalosporins) and the absence of blaIMI-1 in the panel of genes targeted by molecular diagnostic kits.
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Carbapenem- and Colistin-Resistant Enterobacter cloacae from Delta, Colorado, in 2015. Antimicrob Agents Chemother 2016; 60:3141-4. [PMID: 26883705 DOI: 10.1128/aac.03055-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/09/2016] [Indexed: 11/20/2022] Open
Abstract
Resistance to carbapenems in Enterobacteriaceae is a clinical problem of growing significance. Difficulty in treating multidrug-resistant Gram-negative organisms with conventional antibiotics has led to a renewed and increasing use of polymyxin compounds, such as colistin. Here, we report the isolation of carbapenem- and colistin-resistant Enterobacter cloacae from a polymicrobial lower extremity wound in an ambulatory patient. Whole-genome sequencing demonstrated the presence of chromosomal blaIMI-1 and blaAmpC, as well as numerous efflux pump genes.
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Naas T, Dortet L, Iorga BI. Structural and Functional Aspects of Class A Carbapenemases. Curr Drug Targets 2016; 17:1006-28. [PMID: 26960341 PMCID: PMC5405625 DOI: 10.2174/1389450117666160310144501] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 07/02/2015] [Accepted: 03/05/2016] [Indexed: 01/28/2023]
Abstract
The fight against infectious diseases is probably one of the greatest public health challenges faced by our society, especially with the emergence of carbapenem-resistant gram-negatives that are in some cases pan-drug resistant. Currently,β-lactamase-mediated resistance does not spare even the newest and most powerful β-lactams (carbapenems), whose activity is challenged by carbapenemases. The worldwide dissemination of carbapenemases in gram-negative organisms threatens to take medicine back into the pre-antibiotic era since the mortality associated with infections caused by these "superbugs" is very high, due to limited treatment options. Clinically-relevant carbapenemases belong either to metallo-β- lactamases (MBLs) of Ambler class B or to serine-β-lactamases (SBLs) of Ambler class A and D enzymes. Class A carbapenemases may be chromosomally-encoded (SME, NmcA, SFC-1, BIC-1, PenA, FPH-1, SHV-38), plasmid-encoded (KPC, GES, FRI-1) or both (IMI). The plasmid-encoded enzymes are often associated with mobile elements responsible for their mobilization. These enzymes, even though weakly related in terms of sequence identities, share structural features and a common mechanism of action. They variably hydrolyse penicillins, cephalosporins, monobactams, carbapenems, and are inhibited by clavulanate and tazobactam. Three-dimensional structures of class A carbapenemases, in the apo form or in complex with substrates/inhibitors, together with site-directed mutagenesis studies, provide essential input for identifying the structural factors and subtle conformational changes that influence the hydrolytic profile and inhibition of these enzymes. Overall, these data represent the building blocks for understanding the structure-function relationships that define the phenotypes of class A carbapenemases and can guide the design of new molecules of therapeutic interest.
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Affiliation(s)
- Thierry Naas
- Service de Bactériologie- Hygiène, Hôpital de Bicêtre, APHP, EA7361, Faculté de Médecine Paris- Sud, LabEx LERMIT, Le Kremlin-Bicêtre, France.
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Complex Regulation Pathways of AmpC-Mediated β-Lactam Resistance in Enterobacter cloacae Complex. Antimicrob Agents Chemother 2015; 59:7753-61. [PMID: 26438498 DOI: 10.1128/aac.01729-15] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 09/30/2015] [Indexed: 01/10/2023] Open
Abstract
Enterobacter cloacae complex (ECC), an opportunistic pathogen causing numerous infections in hospitalized patients worldwide, is able to resist β-lactams mainly by producing the AmpC β-lactamase enzyme. AmpC expression is highly inducible in the presence of some β-lactams, but the underlying genetic regulation, which is intricately linked to peptidoglycan recycling, is still poorly understood. In this study, we constructed different mutant strains that were affected in genes encoding enzymes suspected to be involved in this pathway. As expected, the inactivation of ampC, ampR (which encodes the regulator protein of ampC), and ampG (encoding a permease) abolished β-lactam resistance. Reverse transcription-quantitative PCR (qRT-PCR) experiments combined with phenotypic studies showed that cefotaxime (at high concentrations) and cefoxitin induced the expression of ampC in different ways: one involving NagZ (a N-acetyl-β-D-glucosaminidase) and another independent of NagZ. Unlike the model established for Pseudomonas aeruginosa, inactivation of DacB (also known as PBP4) was not responsible for a constitutive ampC overexpression in ECC, whereas it caused AmpC-mediated high-level β-lactam resistance, suggesting a post-transcriptional regulation mechanism. Global transcriptomic analysis by transcriptome sequencing (RNA-seq) of a dacB deletion mutant confirmed these results. Lastly, analysis of 37 ECC clinical isolates showed that amino acid changes in the AmpD sequence were likely the most crucial event involved in the development of high-level β-lactam resistance in vivo as opposed to P. aeruginosa where dacB mutations have been commonly found. These findings bring new elements for a better understanding of β-lactam resistance in ECC, which is essential for the identification of novel potential drug targets.
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Lupo A, Papp-Wallace KM, Sendi P, Bonomo RA, Endimiani A. Non-phenotypic tests to detect and characterize antibiotic resistance mechanisms in Enterobacteriaceae. Diagn Microbiol Infect Dis 2013; 77:179-94. [PMID: 24091103 DOI: 10.1016/j.diagmicrobio.2013.06.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Accepted: 06/12/2013] [Indexed: 02/07/2023]
Abstract
In the past 2 decades, we have observed a rapid increase of infections due to multidrug-resistant Enterobacteriaceae. Regrettably, these isolates possess genes encoding for extended-spectrum β-lactamases (e.g., blaCTX-M, blaTEM, blaSHV) or plasmid-mediated AmpCs (e.g., blaCMY) that confer resistance to last-generation cephalosporins. Furthermore, other resistance traits against quinolones (e.g., mutations in gyrA and parC, qnr elements) and aminoglycosides (e.g., aminoglycosides modifying enzymes and 16S rRNA methylases) are also frequently co-associated. Even more concerning is the rapid increase of Enterobacteriaceae carrying genes conferring resistance to carbapenems (e.g., blaKPC, blaNDM). Therefore, the spread of these pathogens puts in peril our antibiotic options. Unfortunately, standard microbiological procedures require several days to isolate the responsible pathogen and to provide correct antimicrobial susceptibility test results. This delay impacts the rapid implementation of adequate antimicrobial treatment and infection control countermeasures. Thus, there is emerging interest in the early and more sensitive detection of resistance mechanisms. Modern non-phenotypic tests are promising in this respect, and hence, can influence both clinical outcome and healthcare costs. In this review, we present a summary of the most advanced methods (e.g., next-generation DNA sequencing, multiplex PCRs, real-time PCRs, microarrays, MALDI-TOF MS, and PCR/ESI MS) presently available for the rapid detection of antibiotic resistance genes in Enterobacteriaceae. Taking into account speed, manageability, accuracy, versatility, and costs, the possible settings of application (research, clinic, and epidemiology) of these methods and their superiority against standard phenotypic methods are discussed.
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Affiliation(s)
- Agnese Lupo
- Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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First report of a nonmetallocarbapenemase class A carbapenemase in an Enterobacter cloacae isolate from Colombia. Antimicrob Agents Chemother 2013; 57:3457. [PMID: 23612204 DOI: 10.1128/aac.02425-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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First identification of blaIMI-1 in an Enterobacter cloacae clinical isolate from France. Antimicrob Agents Chemother 2011; 56:1664-5. [PMID: 22203599 DOI: 10.1128/aac.06328-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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AmpDI is involved in expression of the chromosomal L1 and L2 beta-lactamases of Stenotrophomonas maltophilia. Antimicrob Agents Chemother 2009; 53:2902-7. [PMID: 19414581 DOI: 10.1128/aac.01513-08] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two ampD homologues, ampD(I) and ampD(II), of Stenotrophomonas maltophilia have been cloned and analyzed. Comparative genomic analysis revealed that the genomic context of the ampD(II) genes is quite different, whereas that of the ampD(I) genes is more conserved in S. maltophilia strains. The ampD system of S. maltophilia is distinct from that of the Enterobacteriaceae and Pseudomonas aeruginosa in three respects. (i) AmpD(I) of S. maltophilia is not encoded in an ampDE operon, in contrast to what happens in the Enterobacteriaceae and P. aeruginosa. (ii) The AmpD systems of the Enterobacteriaceae and P. aeruginosa are generally involved in the regulation of ampR-linked ampC gene expression, while AmpD(I) of S. maltophilia is responsible for the regulation of two intrinsic beta-lactamase genes, of which the L2 gene, but not the L1 gene, is linked to ampR. (iii) S. maltophilia exhibits a one-step L1 and L2 gene derepression model involving ampD(I), distinct from the two- or three-step derepression of the Enterobacteriaceae and P. aeruginosa. Moreover, the ampD(I) and ampD(II) genes are constitutively expressed and not regulated by the inducer and AmpR protein, and the expression of ampD(II) is weaker than that of ampD(I). Finally, AmpD(II) is not associated with the derepression of beta-lactamases, and its role in S. maltophilia remains unclear.
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Poirel L, Pitout JD, Nordmann P. Carbapenemases: molecular diversity and clinical consequences. Future Microbiol 2007; 2:501-12. [PMID: 17927473 DOI: 10.2217/17460913.2.5.501] [Citation(s) in RCA: 219] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Carbapenemases are beta-lactamases that hydrolyze most beta-lactams including carbapenems. Carbapenemases are classified in four molecular classes; those belonging to class A are the chromosomally-encoded and clavulanic acid-inhibited IMI, NMC-A and SME, identified in Enterobacter cloacae and Serratia marcescens; the plasmid-encoded KPC enzymes identified in Enterobacteriaceae (and rarely in Pseudomonas aeruginosa); and the GES-type enzymes identified in Enterobacteriaceae and P. aeruginosa. The class B enzymes are the most clinically-significant carbapenemases; they are metallo-beta-lactamases, mostly of the IMP and the VIM series. They have been reported worldwide and their genes are plasmid- and integron-located, hydrolyzing all beta-lactams with the exception of aztreonam. One single plasmid-mediated AmpC beta-lactamase, CMY-10, identified in an Enterobacter aerogenes isolate, has been shown to be a cephaslosporinase with some carbapenemase properties. Finally, the class D carbapenemases are being increasingly reported, mostly in Acinetobacter baumannii, and they compromise the efficacy of imipenem and meropenem significantly.
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Affiliation(s)
- Laurent Poirel
- Université Paris XI, Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Punblique/Hôpitaux de Paris, Faculté de Médecine Paris-Sud, 94275 K.-Bicêtre, France.
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Abstract
Carbapenems, such as imipenem and meropenem, are most often used to treat infections caused by enterobacteria that produce extended-spectrum beta-lactamases, and the emergence of enzymes capable of inactivating carbapenems would therefore limit the options for treatment. Carbapenem resistance in Enterobacteriaceae is rare, but class A beta-lactamases with activity against the carbapenems are becoming more prevalent within this bacterial family. The class A carbapenemases can phylogenetically be segregated into six different groups of which four groups are formed by members of the GES, KPC, SME, IMI/NMC-A enzymes, while SHV-38 and SFC-1 each separately constitute a group. The genes encoding the class A carbapenemases are either plasmid-borne or located on the chromosome of the host. The bla(GES) genes reside as gene cassettes on mainly class I integrons, whereas the bla(KPC) genes and a single bla(IMI-2) gene are flanked by transposable elements on plasmids. Class A carbapenemases hydrolyse penicillins, classical cephalosporins, monobactam, and imipenem and meropenem, and the enzymes are divided into four phenotypically different groups, namely group 2br, 2be, 2e and 2f, according to the Bush-Jacoby-Medeiros classification system. Class A carbapenemases are inhibited by clavulanate and tazobactam like other class A beta-lactamases.
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Affiliation(s)
- Jan Walther-Rasmussen
- Department of Clinical Microbiology, 9301, Rigshospitalet, National University Hospital, Copenhagen, Denmark.
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Radice M, Power P, Gutkind G, Fernández K, Vay C, Famiglietti A, Ricover N, Ayala JA. First class a carbapenemase isolated from enterobacteriaceae in Argentina. Antimicrob Agents Chemother 2004; 48:1068-9. [PMID: 14982814 PMCID: PMC353161 DOI: 10.1128/aac.48.3.1068-1069.2004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Pottumarthy S, Moland ES, Juretschko S, Swanzy SR, Thomson KS, Fritsche TR. NmcA carbapenem-hydrolyzing enzyme in Enterobacter cloacae in North America. Emerg Infect Dis 2003; 9:999-1002. [PMID: 12967501 PMCID: PMC3020613 DOI: 10.3201/eid0908.030096] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
An imipenem-resistant Enterobacter cloacae isolate was recovered from the blood of a patient with a hematologic malignancy. Analytical isoelectric focusing, inhibitor studies, hydrolysis, induction assays, and molecular sequencing methods confirmed the presence of a NmcA carbapenem-hydrolyzing enzyme. This first report of NmcA detected in North America warrants further investigation into its distribution and clinical impact.
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Affiliation(s)
- Sudha Pottumarthy
- University of Washington School of Medicine, Seattle, Washington, USA
| | | | - Stefan Juretschko
- University of Washington School of Medicine, Seattle, Washington, USA
| | - Susan R. Swanzy
- University of Washington School of Medicine, Seattle, Washington, USA
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Abstract
Carbapenemases may be defined as beta-lactamases that significantly hydrolyze at least imipenem or/and meropenem. Carbapenemases involved in acquired resistance are of Ambler molecular classes A, B, and D. Class A, clavulanic acid-inhibited carbapenemases are rare. They are either chromosomally encoded (NMC-A, Sme-1 to Sme-3, IMI-1) in Enterobacter cloacae and Serratia marcescens, or plasmid encoded, such as KPC-1 in Klebsiella pneumoniae and GES-2 in Pseudomonas aeruginosa, the latter being a point-mutant of the clavulanic acid-inhibited extended-spectrum beta-lactamase GES-1. The class B enzymes are the most clinically significant carbapenemases. They are metalloenzymes of the IMP or VIM series. They have been reported worldwide but mostly from South East Asia and Europe. Metalloenzymes, whose genes are plasmid and integron located, hydrolyze virtually all beta-lactams except aztreonam. Finally, the class D carbapenemases are increasingly reported in Acinetobacter baumannii but compromise imipenem and meropenem susceptibility only marginally. The sources of the acquired carbapenemase genes remain unknown, as does the relative importance of the spread of epidemic strains as opposed to the spread of plasmid- or integron-borne genes. Because most of these carbapenemases confer only reduced susceptibility to carbapenems in Enterobacteriaceae, they may remain underestimated as a consequence of the lack of their detection.
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Affiliation(s)
- P Nordmann
- Service de Bactériologie-Virologie, Hôpital de Bicêtre, Assistance Publique-Hôpitaux de Paris and Faculté de Médecine Paris-Sud, Université Paris XI, Paris, France.
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