Antimicrobial susceptibility and oxymino-β-lactam resistance mechanisms in Salmonella enterica and Escherichia coli isolates from different animal sources

The impact of extended-spectrum beta-lactamases (ESBLs) and plasmid-mediated AmpC beta-lactamases (PMA beta s) of animal origin has been a public health concern. In this study, 562 Salmonella enterica and 598 Escherichia coli isolates recovered from different animal species and food products were tested for antimicrobial resistance. Detection of ESBL-, PMA beta-, plasmid-mediated quinolone resistance (PMQR)-encoding genes and integrons was performed in isolates showing non-wild-type phenotypes. Susceptibility profiles of Salmonella spp. isolates differed according to serotype and origin of the isolates. The occurrence of cefotaxime non-wild-type isolates was higher in pets than in other groups. In nine Salmonella isolates, bla(CTX-M) (n = 4), bla(SHV-12) (n = 1), bla(TEM-1) (n = 2) and bla(CMY-2) (n = 2) were identified. No PMQR-encoding genes were found. In 47 E. coli isolates, bla(CTX-M) (n = 15), bla(SHV-12) (n = 2), bla(CMY-2) (n = 6), bla(TEM-type) (n = 28) and PMQR-encoding genes qnrB (n = 2), qnrS (n = 1) and aac(6')-Ib-cr (n = 6) were detected. To the best of our knowledge, this study is the first to describe the presence of bla(CMY-2) (n = 2) and bla(SHV-12) (n = 1) genes among S. enterica from broilers in Portugal. This study highlights the fact that animals may act as important reservoirs of isolates carrying ESBL-, PMA beta- and PMQR-encoding genes that might be transferred to humans through direct contact or via the food chain. (C) 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.