Purpose: The purpose of this evaluation was to compare the 3M™ Molecular Detection Assay E. coli O157 (including H7) protocol to the USDA/FSIS-MLG method for raw ground beef.
Methods: A total of 77 samples were artificially inoculated at a level of 10 CFU/65 g with five strains of E. coli O157:H7 and one strain of E. coli O157: non-toxigenic HNT, isolated in Argentina from foods. Sixteen strains of non-E. coli were analyzed to determine the specificity of the method in levels of 10 CFU/65 g.
Results: All contaminated samples with E. coli O157 were detected by the MDS as positive in real time after 15 minutes. All contaminated samples with non-E. coli were detected as negative with the system in 75 minutes.
The results also indicate 100% inclusivity and 100% exclusivity with no false positives or false negatives. Additionally, this study demonstrated the usefulness of this molecular assay owing to its rapidity, sensitivity and specificity, and how these features can be applied directly in the field of the food industry for detecting prevalent pathogens in Argentina.
Significance: Statistically, there was no significant difference between the MDS E. coli O157 (including H7) when compared to the USDA/FSIS-MLG reference methods as indicated by McNemar’s X2 value of 0.0. The MDS E. coli O157 provides a rapid and accurate solution for the detection of E. coli O157 in raw ground beef.