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P1-124 Validation of the DuPont BAX System X5 for Detection of Salmonella spp. and Escherichia coli O157:H7 from Foods

Monday, August 1, 2016
America's Center - St. Louis
Dawn Fallon, DuPont Nutrition & Health, Wilmington, DE
Steven Hoelzer, DuPont Nutrition & Health, Wilmington, DE
F. Morgan Wallace, DuPont Nutrition & Health, Wilmington, DE
Teresa Brodeur, DuPont Nutrition & Health, Wilmington, DE
Nisha Corrigan, DuPont Nutrition & Health, Wilmington, DE
Andrew Farnum, DuPont Nutrition & Health, Wilmington, DE
Julie Weller, DuPont Nutrition & Health, Wilmington, DE
Eugene Davis, DuPont Nutrition & Health, Wilmington, DE
Jeffrey Rohrbeck, DuPont Nutrition & Health, Wilmington, DE
Alain Minelli, DuPont Nutrition & Health, Wilmington, DE
Gongbo Wang, DuPont Nutrition & Health, Wilmington, DE
Lois Fleck, DuPont Nutrition & Health, Wilmington, DE
Stephen Varkey, DuPont Nutrition & Health, Wilmington, DE
Introduction:  Salmonella and E. coli O157:H7 are found in many food and environmental sources and can cause serious illness. Since isolation by culture can be a lengthy and labor intensive process, especially in the presence of competing flora, rapid simple methods for their detection are needed. 

Purpose:  This study evaluated inclusivity, exclusivity, and detection capabilities of the DuPont BAX System X5 PCR assays for Salmonella species and E. coli O157:H7 for detecting these pathogens in a variety of food types.  

Methods:  Salmonella species (n=112 strains) and E. coli O157:H7 (n=45) inclusivity testing was performed at ~105 CFU/ml, while exclusivity testing (n=48 and n=46, respectively) was performed at ~108 CFU/ml.

For method effectiveness, 2 different foods (ground beef and romaine lettuce) for Salmonella species and 3 different foods (raw beef trim, romaine lettuce and red leaf lettuce) for E. coli O157:H7 were inoculated at fractional positive levels and evaluated using the BAX System X5 PCR assays.  All samples were culture confirmed following either the FDA-BAM or USDA-FSIS MLG reference method.

Results:  The collection of strains evaluated demonstrated 100% inclusivity for the target organisms.  Testing using non-target strains for both assays demonstrated 100% exclusivity. For effectiveness testing, 240 PCR tests were performed across all matrix/media/enrichment/time conditions with a >98% concordance to culture confirmation. Analysis using the AOAC POD model indicated PCR and culture results were statistically indistinguishable.     

Significance:  This study indicates that the BAX® System X5 PCR assays for Salmonella and E. coli O157:H7 are a rapid and sensitive method for detecting these pathogens in food.  Test kit results demonstrated no significant difference when compared with the reference culture methods.

Back to: Poster Session 1 – Produce, Meat, Poultry and Eggs, Non-microbial Food Safety; Laboratory and Detection Methods; Communication Outreach and Education; Seafood; Antimicrobials; Food Toxicology
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