Vol.76 No.4

　Extended-spectrum cephalosporin-resistant Enterobacterales are among the most prevalent antimicrobial-resistant organisms in Gram-negative bacteria, and their spread in the veterinary field is of global concern. We determined the contamination rate of extended-spectrum cephalosporin-resistant Enterobacterales in domestic and imported retail chickens in Japan, and examined their antimicrobial resistance and molecular characteristics. Fifty-three domestic and thirty-nine imported retail chickens were purchased, and antimicrobial susceptibility, β-lactamase encoding genes, sequence type, and incompatibility type of plasmids were assessed in the isolates. The contamination rates of cefotaxime-resistant Enterobacterales isolated from domestic and imported retail chickens were 60.4% and 87.2%, respectively (p ＜ 0.05). Approximately 50% of isolates harbored the bla_CTX-M gene, with bla_CTX-M-1 and bla_CTX-M-2 groups predominating domestic and imported samples, respectively. The gene for plasmid-mediated AmpC was detected in 34% and 33% of isolates from domestic and imported samples, respectively. Isolates possessing bla_CIT with IncK plasmids were found in the isolates from both sample groups. Additionally, our results indicated that the IncK plasmid had the potential for transconjugation with bla_CIT. Escherichia coli sequence type (ST) 57 and ST117 were predominant, followed by ST38. The findings of this study suggest that the high contamination rate of drug-resistant bacteria in retail chicken meat leads to frequent exposure to these pathogens by the general public in Tokyo and Kanagawa, Japan.