Dataset Information

OXA ?-lactamases.

ABSTRACT: The OXA ?-lactamases were among the earliest ?-lactamases detected; however, these molecular class D ?-lactamases were originally relatively rare and always plasmid mediated. They had a substrate profile limited to the penicillins, but some became able to confer resistance to cephalosporins. From the 1980s onwards, isolates of Acinetobacter baumannii that were resistant to the carbapenems emerged, manifested by plasmid-encoded ?-lactamases (OXA-23, OXA-40, and OXA-58) categorized as OXA enzymes because of their sequence similarity to earlier OXA ?-lactamases. It was soon found that every A. baumannii strain possessed a chromosomally encoded OXA ?-lactamase (OXA-51-like), some of which could confer resistance to carbapenems when the genetic environment around the gene promoted its expression. Similarly, Acinetobacter species closely related to A. baumannii also possessed their own chromosomally encoded OXA ?-lactamases; some could be transferred to A. baumannii, and they formed the basis of transferable carbapenem resistance in this species. In some cases, the carbapenem-resistant OXA ?-lactamases (OXA-48) have migrated into the Enterobacteriaceae and are becoming a significant cause of carbapenem resistance. The emergence of OXA enzymes that can confer resistance to carbapenems, particularly in A. baumannii, has transformed these ?-lactamases from a minor hindrance into a major problem set to demote the clinical efficacy of the carbapenems.

SUBMITTER: Evans BA

PROVIDER: S-EPMC3993105 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature

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OXA β-lactamases.

Evans Benjamin A BA Amyes Sebastian G B SG

Clinical microbiology reviews 20140401 2

The OXA β-lactamases were among the earliest β-lactamases detected; however, these molecular class D β-lactamases were originally relatively rare and always plasmid mediated. They had a substrate profile limited to the penicillins, but some became able to confer resistance to cephalosporins. From the 1980s onwards, isolates of Acinetobacter baumannii that were resistant to the carbapenems emerged, manifested by plasmid-encoded β-lactamases (OXA-23, OXA-40, and OXA-58) categorized as OXA enzymes ...[more]

PMID: 24696435

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Project description:Purpose:The emergence of multidrug-resistant Klebsiella pneumoniae (K. pneumoniae) is associated with the acquisition of multiple carbapenemases. Their clonal spread is a worldwide concern due to their critical role in nosocomial infections. Therefore, the identification of high-risk clones with antibiotic resistance genes is very crucial for controlling its global spread. Materials and Methods:A total of 227 K. pneumoniae strains collected during April 2018 to November 2019 were confirmed by PCR. Carbapenemases and extended-spectrum ?-lactamases (ESBL) were detected phenotypically. Confirmation of carbapenemases was carried out by PCR and Sanger sequencing. The clonal lineages were assigned to selected isolates by multilocus sequence typing (MLST), and the plasmid analysis was done by PCR-based detection of the plasmid replicon typing. Results:Of the total K. pneumoniae, 117 (51.5%) were carbapenem resistant (CRKP) and 140 (61.7%) were identified as ESBL producers. Intermediate to high resistance was detected in the tested ?-lactam drugs while polymyxin-B and tigecycline were found to be susceptible. Among CRKP, 91 (77.8%) isolates were detected as carbapenemase producing, while 55 (47%) were positive for bla NDM-1 23.9% (n=28), bla OXA-48 22.2% (n=26) and bla VIM 0.85% (n=1) while 12.7% (n=7) carried both bla NDM-1 and bla OXA-48 genes. The CRKP coharboring bla NDM-1 and bla OXA-48 genes (n=7) were positive for bla CTX-M bla SHV (n=3), bla SHV (n=1) and bla CTX-M (n=3). The novel CRKP with the coexistence of bla NDM-1, bla OXA-48, bla CTX-M and bla SHV genes were associated with the high-risk clone ST147 (n=5) and ST11 (n=2). The assigned replicon types were IncL/M, IncFII, IncA/C and IncH1. Conclusion:This is the first report of the coexistence of bla NDM-1, bla OXA-48, bla CTX-M and bla SHV genes on a high-risk lineage ST147 from Pakistan. This study highlights the successful dissemination of carbapenemase resistance genes in the high-risk clones that emphasizes the importance of monitoring and controlling the spread of these diverse clones globally.

Dataset Information

OXA ?-lactamases.

Publications

OXA β-lactamases.

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