Determination of extended spectrum β-lactamases/AmpC β-lactamases and plasmid-mediated quinolone resistance in Escherichia coli isolates obtained from bovine carcasses in Mexico

Food-borne bacterial infections have worldwide importance, and a great variety of antibiotic resistance mechanisms, mainly of the chromosome type, have rapidly developed. Antimicrobial resistance was determined in this study in terms of the presence of extended-spectrum beta-lactamases (ESBLs), plasmid AmpC beta-lactamases (pAmpC), and plasmid-mediated quinolone resistance (PMQR) from 155 Escherichia coli isolates obtained from bovine carcasses from two states in Mexico (states of Mexico and Jalisco). Isolates were challenged with beta-lactam antimicrobials (ampicillin, ceftazidime, and cefotaxime) and quinolones (nalidixic acid and ciprofloxacin). The presence of the bla (TEM), bla (SHV), bla (CTX-M), bla (OXA) , bla (CMY), bla (MOX), bla (LAT), bla (BIL), qnrA, qnrB, qnrS, aac(6')-Ib-cr, and qepA genes was examined by PCR. Clonal relationship was determined using pulsed-field gel electrophoresis (PFGE). The highest resistance was found to be to nalidixic acid (64 %), followed by ampicillin (32 %), ciprofloxacin (10 %), and ceftazidime and cefotaxime (both 1.3 %). bla (CMY) (n = 1), bla (TEM) (n = 24), qnrB (n = 9), and qnrS (n = 7) genes were detected. PFGE analysis showed that the majority of isolates had a different genotypic profile. To our knowledge, this is the first report of the presence of the qnrB, qnrS, and bla (CMY) genes in E. coli isolated from bovine meat in Mexico.