Validation of the Thermo Scientific SureTect™ Escherichia coli O157:H7 and STEC Screening PCR Assay and SureTect™ Escherichia coli STEC Identification PCR Assay for the Detection of Escherichia coli O157:H7 and the Escherichia coli STEC Serotypes (O26, O45, O103, O111, O121, O145) from Fresh Raw Spinach, Fresh Baby Leaves, Fresh Cut Tomatoes, Frozen Raw Beef, Raw Beef Trim, and Beef Carcass Sponges: AOAC Performance Tested MethodSM 012102.

Background: The Thermo Scientific SureTect™ Escherichia coli O157:H7 and STEC Screening PCR Assay and SureTect Escherichia coli STEC Identification PCR Assay are real-time PCR kits for the rapid detection of E. coli O157:H7 and non-E. coli O157 Shiga toxin-producing E. coli (STEC) serotypes (O26, O45, O103, O111, O121, O145) from fresh raw spinach, fresh baby leaves, fresh cut tomatoes, frozen raw beef, raw beef trim, and beef carcass sponges.

Objective: Both assays were evaluated for AOAC®Performance Tested MethodsSM certification.

Methods: Detection and confirmation inclusivity/exclusivity, matrix, product consistency and stability, and robustness studies were conducted. In the matrix studies, the candidate method was validated against United States and international reference methods for STEC serotypes.

Results: Matrix studies showed no statistically significant differences between the candidate and reference method results when analyzed by probability of detection. For each inclusivity/exclusivity study, all inclusivity strains and no exclusivity strains were detected by either kit. Robustness testing demonstrated that the identification assay performed reliably despite method deviations; however, although not statistically significant, the screening assay performance was impacted. Product consistency and stability testing demonstrated no statistically significant differences between kit lots and storage time points.

Conclusion: The data presented show that both assays constitute a rapid and reliable workflow for the detection and confirmation of E. coli O157:H7 and stipulated non-E. coli O157:H7 STEC serotypes from the tested matrixes.

Highlights: Results are obtained in 80 min post-enrichment with both assays run simultaneously, allowing for the detection and confirmation of STEC within a single workflow.