Inventory of extended-spectrum-β-lactamase-producing Enterobacteriaceae in France as assessed by a multicenter study
Résumé
The objective of this study was to perform an inventory of the ESBL-producing Enterobacteriaceae isolates responsible for infections in French hospitals, and to assess the mechanisms associated with ESBL diffusion.
200 non-redundant ESBL-producing Enterobacteriaceae strains isolated from clinical samples were collected during a multi-centric study performed in 18 representative French hospitals. Antibiotic resistance genes were identified by PCR and sequencing experiments. The clonal relatedness between isolates was investigated by the Diversilab system. ESBL-encoding plasmids were compared by PCR-based-replicon-typing and plasmid-multi-locus-sequence-typing.
CTX-M-15, CTX-M-1, CTX-M-14 and SHV-12 were the most prevalent ESBLs (8 to 46.5%). The three CTX-M-type EBSLs were significantly observed in Escherichia coli (37.1%, 24.2% and 21.8% respectively), and CTX-M-15 was the predominant ESBL in Klebsiella pneumoniae (81.1%). SHV-12 was associated with ESBL-encoding Enterobacter cloacae strains (37.9%). qnrB, aac(6')-Ib-cr and aac (3)-II genes were the main plasmid-mediated resistance genes, with prevalence varying between 19.5 and 45% according to the ESBLs. Molecular typing did not identify wide clonal diffusion. Plasmid analysis suggested the diffusion of few numbers of ESBL-encoding plasmids, especially in K. pneumoniae and E. cloacae However, the ESBL-encoding genes were observed in different plasmid replicons according to the bacterial species.
The prevalence of ESBL subtypes is different according to the Enterobacteriaceae species. Plasmid spread is a key determinant of this epidemiology and the link observed between the ESBL-encoding plasmids and the bacterial host explain the differences observed in the Enterobacteriaceae species.
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