Plasmidic resistance to colistin mediated by mcr-1 gene in Escherichia coli clinical isolates in Argentina: A retrospective study, 2012-2018.
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ABSTRACT: Objective:To describe the resistance profile and the genetic characteristics of Escherichia coli isolates that harbor the mobilizable colistin resistance gene mcr-1 in Argentina. Methods:This was a retrospective study of 192 E. coli isolates positive for mcr-1 obtained from 69 hospitals of Buenos Aires City and 14 Argentinean provinces in 2012 - 2018. The antimicrobial susceptibility was performed by agar diffusion, broth macrodilution, and/or agar dilution. Standard polymerase chain reaction (PCR) was performed to detect resistance genes and incompatibility groups; specific PCR was applied to discriminate between blaCTX-M allelic groups and mcr-1.5 variant. The genetic relatedness among isolates was evaluated by XbaI-pulsed field gel electrophoresis and multilocus sequence typing in a subset of isolates. Results:All E. coli isolates showed minimal inhibitory concentrations to colistin ? 4?g/mL; nearly 50% were resistant to third-generation cephalosporins, with CTX-M-2 being the main extended-spectrum ?-lactamase detected. Five E. coli were carbapenemase-producers (3 NDM, 2 KPC). The mcr-1.5 variant was detected in 13.5% of the isolates. No genetic relationship was observed among the mcr-1-positive E. coli clinical isolates, but a high proportion (164/192; 85.4%) of IncI2 plasmids was detected. Conclusions:The presence of IncI2 plasmids among highly diverse E. coli clones suggests that the mcr-1 gene's wide distribution in Argentina may be driven by the horizontal transmission of IncI2 plasmids.
SUBMITTER: Faccone D
PROVIDER: S-EPMC7498280 | biostudies-literature | 2020
REPOSITORIES: biostudies-literature
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