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

Abstract

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.