First Identification ofblaOXA-51-likein Non-baumanniiAcinetobacter spp.

Lee, Yi-Tzu; Turton, Jane F.; Chen, Te‐Li; Wu, Roy Chen-Chih; Chang, Wei-Che; Fung, Chang-Phoné; Chen, Chien-Pei; Cho, Wen-Long; Huang, Li-Yueh; Siu, L. Kristopher

doi:10.1179/joc.2009.21.5.514

Cited by 53 publications

(36 citation statements)

References 17 publications

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“…However, for a few isolates, there was a mismatch between the clonal complex to which they belonged and the bla OXA-51-like gene that they carried. This mismatch, combined with the fact that bla OXA-51-like genes have been identified on plasmids and in other bacterial species (88,(159)(160)(161)(162), demonstrates that these genes can be horizontally transferred and, as such, are not a reliable method for identifying the underlying bacterial genotype. Another typing method that delineated A. baumannii isolates into sequence groups (SGs) also utilizes the bla OXA-51-like genes, casting doubt on its reliability for determining the underlying isolate genotype (163).…”

Section: Association Of Bla Oxa Genes With Global Lineagesmentioning

confidence: 98%

OXA β-Lactamases

2014

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SUMMARY 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 because of their sequence similarity to earlier OXA β-lactamases. It was soon found that every A. baumannii strain possessed a chromosomally encoded OXA β-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 β-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 β-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 β-lactamases from a minor hindrance into a major problem set to demote the clinical efficacy of the carbapenems.

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Section: Association Of Bla Oxa Genes With Global Lineagesmentioning

confidence: 98%

OXA β-Lactamases

2014

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“…Plasmids were purified using a plasmid DNA miniprep kit (Bioman, Taipei, Taiwan) or a plasmid maxikit (Qiagen, Valencia, CA), gel separated, transferred to nylon membranes (Perkin-Elmer, Boston, MA), and hybridized with PCR-generated probes specific for the bla OXA-51 -like and nuc genes. Several representative strains were also selected for mapping the location of the nuc gene using an I-CeuI restriction enzyme mapping method (15). After transfer of the I-CeuI-cut fragments to a nylon membrane, Southern blot analysis was performed using PCR-generated probes specific for the 16S rRNA (17) or nuc genes.…”

Section: Methodsmentioning

confidence: 99%

“…GQ352402). Moreover, a plasmid bearing the ISAba1-bla OXA-51 -like gene (ISAba1-bla OXA-138 ) has also been indentified in an Acinetobacter genomic species 13TU isolate (15). The mobilization of the ISAba1-bla OXA-51 -like gene to plasmids and dissemination of these plasmids will further complicate the management of A. baumannii infections.…”

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confidence: 99%

Emergence and Distribution of Plasmids Bearing the bla _OXA-51 -Like Gene with an Upstream IS Aba1 in Carbapenem-Resistant Acinetobacter baumannii Isolates in Taiwan

Chen

Lee

Kuo

et al. 2010

Antimicrob Agents Chemother

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116

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The bla OXA-51 -like gene with an upstream ISAba1 (ISAba1-bla OXA-51 -like gene) was originally found on the chromosomes of carbapenem-resistant or -susceptible Acinetobacter baumannii isolates. However, a plasmidborne ISAba1-bla OXA-51 -like gene has recently been identified in Acinetobacter genomic species 13TU and several A. baumannii isolates in Taiwan, and all of the isolates are carbapenem resistant. This study aimed to characterize the plasmids bearing the ISAba1-bla OXA-51 -like gene and their significance in A. baumannii. Among the 117 ISAba1-bla OXA-51 -like-harboring isolates collected from 10 hospitals in Taiwan, 58 isolates (49.6%) from 24 clones had the genes located on plasmids that likely originated from a common progenitor. Among the 58 isolates, four had additional copy of the ISAba1-bla OXA-51 -like gene on their chromosomes. Based on the analysis of these four isolates, the plasmid-located ISAba1-bla OXA-51 -like gene appeared to be acquired via one-ended transposition (Tn6080). The isolates with a plasmid bearing the ISAba1-bla OXA-51 -like gene had higher rates of resistance to imipenem (98% versus 46.6%; P < 0.001) and meropenem (98% versus 69%; P ‫؍‬ 0.019) than those with the genes chromosomally encoded, which is most likely due to increased gene dosage provided by the higher copy number of associated plasmids. Transformation with a recombinant plasmid harboring only the ISAba1-bla OXA-51 -like gene was enough to confer a high level of carbapenem resistance to A. baumannii, eliminating the possible contribution of other factors on the original plasmids. This study demonstrated that the carbapenem resistance-associated plasmids carrying the ISAba1-bla OXA-51 -like gene are widespread in A. baumannii strains in Taiwan.

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“…Their potential role in resistance was recognized upon the discovery that promoter-like elements such as ISAba1 could be inserted in front of the coding sequence to drive overexpression of the enzyme (38). Additionally, variants with single or multiple substitutions in the OXA-51 or OXA-66 background have been connected to antibiotic resistance phenotypes (39)(40)(41)(42) and increased hydrolytic activity for carbapenems (43).…”

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confidence: 99%