Screen pre-evisceration and post-intervention carcasses from cull cow slaughter plants and ground beef for Shiga toxin genes to determine the prevalence of non-0157 EHEC/STEC. Isolate non-0157 EHEC/STEC from Shiga toxin positive ground beef and carcass enrichments and characterize isolates in regard to serotypes and virulence factors.
Approach: A total of 6400 carcass samples (collected prior to evisceration and after application of all antimicrobial interventions) and 3200 ground beef samples that have been previously collected and archived at USMARC will be used. Samples will be screened by PCR to identify STEC positive samples. Once Shiga toxin genes are determined to be present, the samples will be processed using a phenotypic screening assay to isolate non-0157 EHEC/STEC for characterization (serotype, and virulence genes).