P3-26 Performance Evaluation of a New Molecular Technology for the Detection of Escherichia coli O157 in Food

Wednesday, July 31, 2013
Exhibit Hall (Charlotte Convention Center)
Adriana Tassinari, 3M Do Brasil Ltda, Jundiai, Brazil
Katia Souza, University of São Paulo, São Paulo, Brazil
John David, 3M Food Safety, St. Paul, MN
Maria Teresa Destro, University of São Paulo, São Paulo, Brazil
Introduction: Escherichia coli is a member of the Enterobacteriaceae family, which are some of the most important enteric pathogens. Although most E. coli do not cause gastrointestinal illnesses, certain groups can cause life-threatening diarrhea and severe disability.

Many innovative technologies are being used for the microbiological analysis of foods. Unlike traditional methods that rely on specific media to select and grow pathogens, developments in molecular biology have led to innovative methods that are easier and more rapid to perform, requiring only minutes to complete. The 3M™ Molecular Detection System (MDS) combines two technologies – isothermal DNA amplification and real-time bioluminescence detection – in a robust platform that is expected to be less prone to matrix interference.  

Purpose: This study was conducted to evaluate the performance of the new system following recommendations from the AOAC guidelines for validation of microbiological methods.

Methods: Samples of foods were spiked with Escherichia coli O157 (at 1-10 CFU/25 g) and with Escherichia coli O103 and Enterobacter aerogenes (10-100 CFU/25 g). Several food categories, including meat, fish and seafood, fruits and vegetable, dairy products, and miscellaneous were evaluated.  Each food product was divided into four 25 g samples: (i) negative control, (ii) spiked with E. coli O157, (iii) spiked with E. coli O103 and E. aerogenes, and (iv) spiked with all three organisms. All 120 samples were enriched and incubated according to the manufacturer’s recommendation. After incubation, the samples were analyzed in duplicate using the MDS.

Results: No matrix interference was observed for any of the food products tested. From 240 tests conducted, the new technology demonstrated 99% repeatability and 99% accuracy.

Significance: The MDS was found to be not only a suitable, but also a practical, rapid, and sensitive method for the detection of E. coli O157 even in the presence of related organisms.