Coprevalence of Plasmid-Mediated Quinolone Resistance Determinants QepA, Qnr, and AAC(6')-Ib-cr among 16S rRNA Methylase RmtB-Producing Escherichia coli Isolates from Pigs

摘要

Plasmid-mediated quinolone resistance determinants, including Qnr peptides and AAC(6')-Ib-cr, are increasingly identified worldwide among various clinical isolates of Enterobacteriaceae(7, 9,10). Very recently, a novel plasmid-mediated fluoroquinolone-resistant determinant, QepA (quinolone efflux pump), which showed a considerable similarity to the major facilitator superfamily-type efflux pumps, was first identified in an Escherichia coli clinical isolate from Japan (13) and later found also in an E. coli isolate in Belgium (6). Interestingly, both of the two qepA -harboring E. coli isolates also contained the rmtB gene encoding a 16S rRNA methyltransferase, an emerging new molecular mechanism responsible for high-level pan-aminoglycoside resistance among gram-negative pathogens (3, 4, 6, 13, 14).Our previous study showed that rmtB was highly prevalent among E. coli isolates from pigs in China (1). The aim of this study was to investigate the prevalence of plasmid-mediated quinolone resistance determinants among rmtB-producmg E. coli isolates from pigs in China and to identify the association of the qepA gene with rmtB.