Indexed on: 22 Sep '18Published on: 22 Sep '18Published in: Poultry science
In the poultry industry, commercial layer farms play an important role in meeting the protein demand through the supply of eggs. However, the risk of contamination by β-lactamase-producing Escherichia coli in eggs laid by commercial chickens is significant. In this study, we investigated the rate of extended-spectrum β-lactamase (ESBL) and plasmid-mediated AmpC (pAmpC) β-lactamase-producing E. coli isolated from layer hens and characterized their molecular background. Among the 92 cefotaxime-resistant E. coli isolates, 66 (71.7%) were identified as multidrug resistant and 29 showed phenotypic and genotypic characteristics of β-lactamase-producing E. coli. The ESBL/pAmpC genes blaCTX-M-1, blaCTX-M-14, blaCTX-M-15, and blaCMY-2 were detected in 1, 6, 5, and 4 isolates, respectively. The non-ESBL/pAmpC gene blaTEM-1 was found in 16 isolates. Three isolates harbored both blaTEM-1 and blaCTX-M-14 genes. A total of 12 isolates also carried class 1 integrons, with 3 different gene cassette arrangements found in 8 of these isolates. A pulsed-field gel electrophoresis (PFGE) analysis of the 29 β-lactamase-producing E. coli isolates revealed that 4 PFGE patterns were consistent with the β-lactamase gene and layer farm origin, and showed a similar antibiotic resistance pattern. Our results suggest that comprehensive surveillance and more prudent use of third-generation cephalosporins in commercial layer farms is necessary to prevent the dissemination of ESBL/pAmpC-producing E. coli.