P3-47 Innovative Solution for the Detection and Confirmation of the TOP7 Shiga Toxin-producing E. coli (STEC) Serogroups in 375g Raw Beef

Tuesday, July 28, 2015
Hall B (Oregon Convention Center)
Marion Bouvier-Crozier , VetAgro-Sup , Marcy L'etoile , France
Xavier Guillarme , VetAgro-Sup , Marcy L'etoile , France
Patrice Chablain , bioMérieux, Inc. , Grenoble , France
Peggy Nomade , bioMérieux , Marcy L'Etoile , France
Delphine Thevenot-Sergentet , VetAgro-Sup , Marcy L'etoile , France
Introduction: Shiga Toxin-producing Escherichia coli (STEC) are an important cause of foodborne illness. This pathogen can be responsible for gastrointestinal diseases ranging from diarrhea to hemorrhagic colitis and hemolytic uremic syndrome. As a result, the food industry needs fast, sensitive and complete methods for STEC detection to ensure a safe food supply.

Purpose: VIDAS UP E. coli Serogroups (ESPT) was developed as a global method using phage recombinant proteins for the immuno-concentration (IC) of E. coli serogroups O157, O26, O103, O111, O145, O45 and O121 from food enrichments. IC will be used both for screening and confirmation steps. The aim of this study was to compare the new alternative method with the ISO 13136 standard.

Methods: For the alternative method, 375 g artificially contaminated raw beef products were ¼ diluted in a selective pre-warmed BPW and enriched for 10 h at 41.5 ± 1°C. For the reference method, 25 g samples were 1/10 diluted in BPW and enriched for 20 h at 37 ± 1°C. DNA was extracted using VIDAS ESP1 protocol or commercial lysis and analyzed by PCR (eae, stx, O-groups). Any positive samples were confirmed by immuno-concentrating the STEC strains with VIDAS ESP2 protocol or commercial IMS from the enrichment broth and streaking the immuno-concentrated samples onto selective agar plates. After incubation, typical colonies were further confirmed by SLIDEX E. coli tests and/or PCR tests.

Results: Among the 56 tested samples, 41 were obtained positive by both the methods. The results obtained for the two methods, in the tested experimental conditions described above, are comparable.

Significance: This study has demonstrated that the VIDAS ESPT assay is a promising tool to screen and isolate STEC strains from food enrichment. This complete alternative solution will provide technical and economic advantages to the food industry for routine testing.