Genetic characterization of three qnrS1-harbouring multidrug-resistance plasmids and qnrS1-containing transposons circulating in Ho Chi Minh City, Vietnam

摘要

Plasmid-mediated quinolone resistance (PMQR) refers to a family of closely related genes that confer decreased susceptibility to fluoroquinolones. PMQR genes are generally associated with integrons and/or plasmids that carry additional antimicrobial resistance genes active against a range of antimicrobials. In Ho Chi Minh City (HCMC), Vietnam, we have previously shown a high frequency of PMQR genes within commensal Enterobacteriaceae . However, there are limited available sequence data detailing the genetic context in which the PMQR genes reside, and a lack of understanding of how these genes spread across the Enterobacteriaceae . Here, we aimed to determine the genetic background facilitating the spread and maintenance of qnrS1, the dominant PMQR gene circulating in HCMC. We sequenced three qnrS1 -carrying plasmids in their entirety to understand the genetic context of these qnrS1 -embedded plasmids and also the association of qnrS1 -mediated quinolone resistance with other antimicrobial resistance phenotypes. Annotation of the three qnrS1 -containing plasmids revealed a qnrS1 -containing transposon with a closely related structure. We screened 112 qnrS1 -positive commensal Enterobacteriaceae isolated in the community and in a hospital in HCMC to detect the common transposon structure. We found the same transposon structure to be present in 71.4?% (45/63) of qnrS1 -positive hospital isolates and in 36.7?% (18/49) of qnrS1 -positive isolates from the community. The resulting sequence analysis of the qnrS1 environment suggested that qnrS1 genes are widely distributed and are mobilized on elements with a common genetic background. Our data add additional insight into mechanisms that facilitate resistance to multiple antimicrobials in Gram-negative bacteria in Vietnam.