Prevalence of Shiga Toxin-Producing Escherichia coli in the Oral Cavity of Calves Raised in Yamaguchi Prefecture

Abstract

During the period from 2006 to 2009, the prevalence of shiga toxin-producing Escherichia coli (STEC) in the oral cavity of calves raised at Farm A in Yamaguchi Prefecture was examined. STEC was isolated in 24 out of 186 oral samples (12.9%). Among the 27 strains of the 24 positive samples, the predominant O serogroup was O26 (13 strains), followed by O untypeable (5 strains), O8 (4 strains), O111 (3 strains) and O119 (2 strains). The strains' antimicrobial susceptibility to 12 different drugs resulted in 24 strains (89%) being resistant to one or more drugs. Among the resistant strains, four O8 and one O111 strains showed resistance to ciplofloxacin, whereas one O26 strain was resistant to fosfomycin. From the results of a pulsed-field gel electrophoresis analysis on the O26 and O111 strains, several strains in each serogroup showed identical or similar patterns, indicating that horizontal transmission of the same clones had occurred among the calves at the farm.