Prevalence and characteristics of extended-spectrum β-lactamase-producing Escherichia coli in domestic and imported chicken meats in Japan

The purpose of this study was to investigate the prevalence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-Ec) in retail chicken meats in Japan. Fifty-six domestic and 50 imported (Brazil, n=36; United States, n=8; Thailand, n=6) chicken meat samples were analyzed. The 162 ESBL-Ec included 111 from 43 (77%) domestic samples and 51 from 26 (52%) Brazilian samples. Fifty-three and 30 of 111 and 51 ESBL-Ec from domestic and Brazilian chickens, respectively, were selected for ESBL genotyping. The bla(CTX-M) (91%), bla(TEM) (36%) and bla(SHV) (15%) genes were detected in ESBL-Ec isolated from domestic chickens, whereas bla(CTX-M) (100%) and bla(TEM) (20%) were detected in ESBL-Ec isolated from imported chickens. Among the bla(CTX-M) group, bla(CTX-M-2) (45%) and bla(CTX-M-1) (34%) were prevalent in domestic chicken isolates, whereas bla(CTX-M-2) (53%) and bla(CTX-M-8) (43%) were prevalent in imported chicken isolates. Domestic chicken isolates were mostly resistant to tetracycline (83%), followed by streptomycin (70%) and nalidixic acid (62%). Imported chicken isolates were resistant to streptomycin (77%), followed by nalidixic acid (63%) and tetracycline (57%). Notably, extensive multidrug resistance was detected in 60% (32/53) and 70% (21/30) ESBL-Ec from domestic and imported chickens, respectively. Virulence genes associated with diarrheagenic and extra-intestinal pathogenic E. coli were detected in ESBL-Ec isolated from domestic and imported chickens. These data suggest that ESBL-Ec in retail chicken meats could be a potential reservoir for antimicrobial resistance determinants and that some are potentially harmful to humans.