Prevalence of Colistin-resistant Escherichia coli Isolated from Cattle in the Tokachi Area of Hokkaido, 2010‐2018

Abstract

The rate of resistance to colistin (CL) in Escherichia coli (E. coli ) strains isolated from cattle in the Tokachi area of Hokkaido between 2010 and 2018 was 19.6% (9/46), and all resistant strains were derived from beef cattle without CL treatment. The results of plasmid transfer tests suggested that mcr-carrying plasmids were transferable with resistance to some antimicrobials other than CL in four strains. Twelve strains showing an MIC value of 2 mg/l or more to CL possessed mcr-1, mcr-3, or mcr-5, eight of which were Shiga toxin-producing E. coli O1, O26 and O111. In this study, CL-resistant pathogenic E. coli strains possessing mcr were detected in cattle; therefore, prudent use of antimicrobials on farms is required to prevent transmission of mcr-possessing strains to humans via livestock products.