Serotypes and virulotypes of non-O157 shiga-toxin producing Escherichia coli (STEC) on bovine hides and carcasses

Four hundred and fifty beef animal hides and a similar number of carcasses were screened for STEC in 3 beef abattoirs over a 12 month period using PCR and culture based methods. 67% (301/450) of hides and 27% (122/450) of carcasses were STEC PCR positive. Forty isolates representing 12 STEC serotypes (O5:H-, O13:H2, O26:H11, O33:H11, O55:H11, O113:H4, O128:H8, O136:H12, O138:H48, O150:H2, O168:H8 and ONT:H11) and 15 serotype–virulotype combinations were identified. This study provides much needed non-O157 STEC surveillance data and also provides further evidence of bovines as a source of clinically significant STEC as well as identifying 3 emerging serotypes O5:H- (eae-β1), O13:H2 (eae-ζ), and O150:H2 (eae-ζ) that should be considered when developing beef testing procedures for non-O157 STEC. ► 67% (301/450) of hides and 27% (122/450) of carcasses were STEC PCR positive. ► Forty isolates representing 15 serotype-virulotype combinations were recovered. ► Approximately 80% of isolates carried shiga-toxin and eaeA or putative adhesion genes. ► LEE-negative STEC strains are not a clonal group of pathogens. ► O5:H- (eae-β1), O13:H2 (eae-ζ), and O150:H2 (eae-ζ) are emerging pathogens.