Rapid PCR detection of enterohemorrhagic Escherichia coli (EHEC) in bovine food products and feces

Abstract

Although Escherichia coli (E. coli) O157:H7 is a major cause of foodborne illness, other types of E. coli can also cause illness. E. coli that possess the eae gene for attachment and effacing have the potential to cause disease. Many real-time, molecular-based assays have been developed to detect Enterohemorrhagic E. coli (EHEC) including E. coli O157:H7. However, no assay currently exists to detect the eae gene present in E. coli O157:H7 and other EHEC strains with a confirmed positive or negative result in less than 12 h. Raw beef food products (raw ground beef and raw boneless beef) at 25 and 375 g samples and bovine fecal samples at 2 g were inoculated with 10(1), 10(3), 10(4), and 10(5) organisms of E. coli O157:H7 to test the sensitivity of this assay. Fourteen different foodborne bacteria (including E. coli O157:H7) and 19 various E. coli strains, obtained from the United States Department of Agriculture-Agricultural Research Service (USDA-ARS) were tested for specificity. E. coli O157:H7 was detected at the level of 10(1) organisms in both 25 and 375 g samples of raw ground and raw boneless beef products as well as 2 g samples of bovine feces after pre-enrichment and concentration. None of the 14 foodborne bacteria screened for cross-reactivity was detected. All USDA E. coli strains confirmed to contain the eae gene were detected.