Characteristics of ESBL-producing Enterobacteriaceae and Methicillinresistant Staphylococcus aureus (MRSA) isolated from Swiss and imported raw poultry meat collected at retail level.

INTRODUCTION: This study was conducted to investigate the occurrence and genetic characteristics of extended spectrum β-lactamase (ESBL) and methicillin-resistant Staphylococcus aureus (MRSA) in 80 samples of Swiss (n=36) and imported (n=44) raw chicken meat collected at retail level. In addition, ESBL-producers were screened for the presence of the plasmid-mediated colistin resistance gene mcr-1. Countries of import included Argentina (n=2), Austria (n=1), Brazil (n=3), Denmark (n=5), France (n=1), Germany (n=13), Hungary (n=5), Italy (n=8), and Slovenia (n=6). Forty ESBL-producing E. coli strains were isolated from 33 (41.3%) of the 80 samples, comprising seven (19.4%) of the Swiss and 26 (59%) of the imported samples. The most common blaESBL among the isolates were blaCTX-M-1 (n=14) and blaSHV-12 (n=16). Other genes comprised blaTEM-52 (n=4), blaCTX-M-2 (n=3), blaCTX-M-8 (n=1), blaCTX-M-14 (n=1) and a novel blaCTX-M-14-like variant (n=1). Two ESBL-producers isolated from samples from Germany (n=1) and Italy (n=1) tested additionally positive for the plasmid-mediated colistin resistance gene mcr-1. Six (7.5%) samples, all imported from Germany, were found to contain MRSA. Three isolates belonged to the livestock-associated CC398-MRSA-V-t034, and 3 to CC9-MRSA-IV-t13177, described here for the first time in chicken meat.