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J. WILLFORD, Dept. of Animal Science, Univ. of Wyoming, 1000 East University Avenue, Dept. 3684, Laramie, WY 82071-3684 and L. D. Goodridge, Dept. of Animal Science, Univ. of Wyoming, 1000 East University Avenue, Dept. 3684, Laramie, WY 82071-3684. Shiga-toxin producing Escherichia coli (STEC) are an important cause of foodborne illness. Since all STEC isolates produce toxins (shiga-toxin 1, shiga-toxin 2, or both), it is possible to use the presence of shiga-toxins within a sample, as an indicator of the presence of STEC within that same sample.The objective of this study was to evaluate three commercially available kits for their ability to identify shiga-toxins in STEC isolates, and in bovine feces. Each test kit was evaluated for its ability to detect toxin in a total of 73 strains comprising 20 STEC serotypes. Additionally, we assayed six strains known to produce variant shiga-toxins. Each strain was cultured overnight in tryptic soy broth, and the following day, the cultures were evaluated for toxin production using three commercially available kits: the Meridian Premier EHEC kit, the Remel ProSpecT Kit, and the r-Biopharm Ridascreen Verotoxin kit, according to the manufacturer's instructions. Two known toxin positive strains (O157:H7 and O111:H8) were evaluated to determine if toxin could be detected directly in bovine feces. Both strains were inoculated into feces, enriched overnight, and subjected to the toxin tests as described. The results indicated that all three kits were effective at detecting toxin in the STEC isolates. Overall, the three kits agreed on 72 of the 73 strains tested. The Meridian and Remel kits gave positive results for four of the variant toxins, while the r-Biopharm kit was only able to detect three of the variant toxins. In addition, with an overnight enrichment it was possible to directly detect toxin in bovine feces. These results demonstrate the efficacy of using shiga-toxin detection kits as a rapid screening method to determine the presence of STEC in bovine feces. These tests could be used to screen cattle for the presence of STEC just prior to slaughter.
Session 33, Food Microbiology: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |