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P1-106 Detection of E. coli O157:H7, Non-O157 STEC and Salmonella from a Single 25-g or 375-g Enrichment of Spinach Using the DuPont BAX System

Monday, August 1, 2016
America's Center - St. Louis
Julie Weller, DuPont Nutrition & Health, Wilmington, DE
Teresa Brodeur, DuPont Nutrition & Health, Wilmington, DE
Nisha Corrigan, DuPont Nutrition & Health, Wilmington, DE
Dawn Fallon, DuPont Nutrition & Health, Wilmington, DE
Steven Hoelzer, DuPont Nutrition & Health, Wilmington, DE
Andrew Farnum, DuPont Nutrition & Health, Wilmington, DE
F. Morgan Wallace, DuPont Nutrition & Health, Wilmington, DE
Troy Ayers, DuPont Nutrition & Health, Wilmington, DE
Pheakdey Ith, DuPont Nutrition & Health, Wilmington, DE
Stacy Stoltenberg, DuPont Nutrition & Health, Wilmington, DE
Introduction: Enteric pathogens such as Escherichia coli O157:H7 and Salmonella are the leading cause of fresh produce associated diseases. Due to the short shelf life of produce, PCR testing is often used to detect these pathogens to achieve rapid, highly sensitive results. However, plant substances such as polysaccharides and polyphenols present a challenge to these detection systems.

Purpose: The purpose of this study was to determine the fastest time-to-result to detect E. coli O157:H7, non-O157 STEC, and Salmonella in spinach from a single 25-g and 375-g sample enrichment.

Methods: Spinach portions of 25 g and 375 g (n=20 each) were fractionally inoculated with E. coli O157:H7, E. coli O26 and Salmonella, held at 4°C for 72 hours, and homogenized with 100 ml or 1,500 ml, respectively, of pre-warmed (42°C) BAX System MP media. Samples were incubated at 42°C for 8-22 hours and tested directly from the primary enrichment and after a BHI regrowth using real-time PCR. Two additional sets of samples were enriched according to the FDA-BAM reference methods for Diarrheagenic E. coli (n=20) and Salmonella (n=20) and tested using real-time PCR to provide a rapid presumptive results in addition to culture.

Results: For 25-g samples, 90 real-time PCR tests were performed with 100% agreement to culture after 10 hours of enrichment with a regrowth. For 375-g samples, 90 real-time PCR tests were performed with >99% agreement to culture after 12 hours of enrichment with a regrowth; statistical analysis demonstrated the difference between methods to be insignificant.  

Significance: The results of this study demonstrate that the BAX System can detect all three organisms simultaneously from a single 25-g or 375-g enrichment of spinach in BAX System MP media.

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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