aac(6′)-Ib-cr is the major plasmid-mediated quinolone resistance determinant in extended-spectrum β-lactamase-producing Escherichia coli in eastern France
Résumé
The aim of this study was to describe the presence of plasmid-mediated quinolone resistance (PMQR) determinants in extended spectrum b-lactamase-producing Escherichia coli (ESBL-Ec) in hospitals in eastern France. All ESBL-Ec isolated from May 2008 to April 2009 in nine hospitals in eastern France were collected and screened by PCR for the presence of PMQR genes. bla genes were identified by PCR and sequencing. Randomly chosen PMQR-positive ESBL-Ec isolates were characterised by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and phylogenetic group identification. Of the 447 ESBL-Ec tested, 122 (27.3%) had a PMQR determinant. aac(60)-Ib-cr was more prevalent (118/122; 96.7%) than qnr [4/122 (3.3%), comprising 2 qnrB2, 1 qnrB1 and 1 qnrA1]. Among 37 PMQR-positive ESBL- Ec isolates selected for typing, 26 (70%) carried blaCTX-M-15 of which 25/26 (96%) co-harboured aac(60)-Ib- cr. Of the 37 isolates, 14 belonged to the B2:ST131 clone, all of which produced AAC(60)-Ib-cr. On the other hand, most of the qnr genes (3/4) were observed in strains carrying bla genes other than blaCTX-M (qnrB2 and blaSHV-12; qnrA1 and blaTEM-52). These findings suggest that aac(60)-Ib-cr, rather than qnr, is the spreading PMQR determinant in ESBL-Ec isolates, and the qnr determinant is not specifically associated with blaCTX-M genes in France. aac(60)-Ib-cr was the predominant PMQR gene in ESBL-Ec isolated in eastern France hospitals, suggesting that the distribution may be due to clonal spread of ST131 CTX-M- 15-producing E. coli isolates.