MOL-PCR For SNP Based Detection and Characterization of STEC non-O157 Strains

Shiga toxin-producing Escherichia coli (STEC) strains are important food-borne pathogens that have been linked to human illness. In the United States, STEC O157:H7 strains have been attributed to the majority of disease and outbreaks; however, the frequency of disease associated with STEC non-O157 strains have also increased and is often under recognized due to diagnostic limitations. In 2012, the Food Safety and Inspection Service (FSIS) implemented mandatory testing for non-O157 STEC serogroups O26, O45, O103, O111, O121, and O145. Single nucleotide polymorphisms (SNPs) have been identified in the O-antigen gene cluster for each of the non-O157 STEC serogroups that can differentiate between a STEC and non-STEC strain. In this study, the multiplex oligonucleotide ligation-PCR (MOL-PCR) detection platform was adapted for the detection and characterization of the above-described non-O157 STEC serogroups. The SNP-based MOL-PCR assay has demonstrated the ability to simultaneously detect the nonO157 serogroups and characterize the strain based on the SNP discriminates identified for each serogroup. This work provides a potential diagnostic platform that can reduce diagnostic limitations for the detection of non-O157 serogroups.