Abstract:

【Objective】 To detect plasmid-mediated quinolone resistance (PMQR) qnr, qepA, aac (6′)-Ib-cr genes in clinical isolates of Enterobacteriaceae from avian in Guangdong province. 【Method】 Susceptibility of 84 strains to 27 antimicrobial agents were determined by agar disc diffusion method. All of the 84 strains were screened for the qnr, qepA, aac (6′)-Ib-cr genes by PCR. Mutations in the quinolone-resistance-determining region (QRDRs) of the gyrA, gyrB, parC and parE gene was detected in PMQR positive strains. 【Result】 The isolates showed high rate of resistance to antimicrobial agents widely used in veterinary clinical medicine such as exrofloxacin, fleroxacin, ampicillin, trimethoprim-sulfamethoxazole, doxycycline, and rifampin, streptomycin and roxithromycin. All of the 84 strains showed multiple-resistance to at least 6 drugs. However most of them were sensitive to ampicillin-sulbactam, aztreonam, polymyxin E and cephalexin. A qnrB6 and aac (6′)-Ib-cr gene was identified in a Klebsiella pneumoniae. Mutation of S→I occurred in the QRDR of the gyrA 83 site, while no mutations were detected in QRDRs of gyrB, parC and parE. 【Conclusion】 Enterobacteriaceae isolated from avian in Guangdong showed high level multiple-resistance to widely used drugs. This is the first report on two PMQR determinants, qnr and aac (6′)-Ib-cr, in clinical isolates of K pneumoniae from avian. The emergency of PMQR genes may indicate a more widespread dissemination of resistance to quinolones in avian industry.

Key words: avian, Enterobacteriaceae, plasmid, quinolones, resistance