Purpose: The purpose of the study was to evaluate the Atlas E. coli O157:H7 Detection Assay sensitivity and specificity as well as detection of E. coli O157:H7 in artificially inoculated high fat ground beef (HFGB) and beef trim (BT) samples.
Methods: HFGB and BT samples in 375g test portions were inoculated with low levels of E. coli O157:H7 and diluted in mTSB or in the media suggested by the reference method. All samples were incubated at 42°C, lysed to release bacterial mRNA and loaded onto the instrument. The instrument combines target capture, transcription-mediated amplification, and hybridization protection assay. The results were compared to the FSIS reference method MLG 5.06. Sensitivity and specificity was evaluated by testing 50 E. coli O157:H7 strains at 10XLOD of 1e4 CFU/mL and 30 non-O157:H7 E. coli strains at 1e8 CFU/mL.
Results: The assay performed equally compared to the FSIS reference method for 375g HFGB and BT samples. No statistically significant difference was observed between the test method and reference method as determined by POD analysis. The test method showed sensitivity of 1e4 CFU/mL by detecting all 50 inclusive organisms and 100% specificity by not detecting 30 exclusive organisms.
Significance: The Atlas® E. coli O157:H7 Detection Assay provides fast and highly accurate detection of pathogenic E. coli O157:H7 in 375g HFGB and BT samples and results were comparable to the FSIS reference method.