Abstract
The aim of this study was to characterize the prevalence of extended-spectrum β-lactamase (ESBL) genes and plasmid-mediated fluoroquinolone resistance (PMQR) determinants in 202 Escherichia coli isolates from chickens in Anhui Province, China, and to determine whether ESBL and PMQR genes co-localized in the isolates. Antimicrobial susceptibility for 12 antimicrobials was determined by broth microdilution. Polymerase chain reactions (PCRs), DNA sequencing, and pulsed field gel electrophoresis (PFGE) were employed to characterize the molecular basis for β-lactam and fluoroquinolone resistance. High rates of antimicrobial resistance were observed, 147 out of the 202 (72.8%) isolates were resistant to at least 6 antimicrobial agents and 28 (13.9%) of the isolates were resistant to at least 10 antimicrobials. The prevalence of bla CTX-M, bla TEM-1 and bla TEM-206 genes was 19.8%, 24.3% and 11.9%, respectively. Seventy-five out of the 202 (37.1%) isolates possessed a plasmid-mediated quinolone resistance determinant in the form of qnrS (n = 21); this determinant occurred occasionally in combination with aac(6′)-1b-cr (n = 65). Coexistence of ESBL and/or PMQR genes was identified in 31 of the isolates. Two E. coli isolates carried bla TEM-1, bla CTX-M and qnrS, while two others carried bla CTX-M, qnrS and aac(6′)-1b-cr. In addition, bla TEM-1, qnrS and aac(6′)-1b-cr were co-located in two other E. coli isolates. PFGE analysis showed that these isolates were not clonally related and were genetically diverse. To the best of our knowledge, this study is the first to describe detection of TEM-206-producing E. coli in farmed chickens, and the presence of bla TEM-206, qnrS and aac(6′)-1b-cr in one of the isolates.
Highlights
The emergence of multidrug-resistant bacteria in the natural environment constitutes a serious risk to domestic animals and humans
The main purpose of this study was to investigate the prevalence of extended-spectrum b-lactamase (ESBL) and plasmidmediated fluoroquinolone resistance (PMQR) genes in E. coli collected recently from four chicken farms and characterization of the b-lactam and fluoroquinolone resistance mechanisms from isolates resistant to these drugs
The inappropriate use and abuse of antibiotics in poultry husbandry lead to enhanced antibiotic resistance
Summary
The emergence of multidrug-resistant bacteria in the natural environment constitutes a serious risk to domestic animals and humans. Extended-spectrum b-lactamases (ESBLs) once constituted the most important cephalosporin resistance mechanism in Enterobacteriaceae, Escherichia coli [1]. Three plasmidmediated fluoroquinolone resistance (PMQR) mechanisms have been described; these include (i) the Qnr (qnrA, qnrB, qnrS, qnrC and qnrD) proteins, (ii) the aac(69)-Ib-cr enzyme, and, (iii) QepA and OqxAB plasmid-mediated efflux pumps [5]. ESBL-producing isolates are commonly associated with PMQR genes in Enterobacteriaceae [6]. Neither ESBL nor PMQR genes in E. coli isolates from chickens have been described in the Anhui Province. The main purpose of this study was to investigate the prevalence of ESBL and PMQR genes in E. coli collected recently from four chicken farms and characterization of the b-lactam and fluoroquinolone resistance mechanisms from isolates resistant to these drugs
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