An official website of the United States government.
<OL> <LI> Determine the prevalence of Salmonella and Listeria and the levels of Salmonella and generic microbial contamination on the hides of slaughter cows and bulls. <LI> Determine the prevalence of Salmonella and Listeria and the levels of Salmonella and generic microbial contamination on cow/bull carcasses before pre-evisceration microbial interventions. <LI> Determine the prevalence of Salmonella and Listeria and the levels of Salmonella and generic microbial contamination on cow/bull carcasses after all microbial interventions.<LI>Determine the prevalence of Salmonella Newport and Salmonella Typhimurium and the multi drug-resistance profiles for those strains.
Approach: Hide, pre-evisceration carcass, and post-wash carcass sponge samples will be obtained from four cow/bull slaughter plants over four seasons. For each plant, sampling will occur on three days with 65 samples of each type obtained on each day for a total of 195 samples of each type per plant and a grand total of 3120 samples of each type. Samples will be transported (2 deg C) to MARC and analyzed for aerobic plate count and prevalence of Salmonella and Listeria and enumeration of Salmonella spp. All samples will be enriched with TSB and incubated for 2 h at 25 deg C, 6 h at 42 deg C, then held at 4 deg C until processing. Following incubation, 1 ml of each enrichment will be subjected to immuno-magnetic separation. The IMS product will be selectively enriched for Salmonella by incubation at 42 deg C in Rappaport-Vassiliadis soya (RVS) broth. RVS broth will be struck to hektoen enteric (HE) and Brilliant Green Agar to isolate colonies of Salmonella. Salmonella isolates will be confirmed by molecular methods. All Salmonella-confirmed isolates will be serogrouped by latex agglutination followed by serotyping using antisera specific for the identification of somatic and flagellar antigens of Salmonella Newport and Salmonella Typhimurium. The antibiotic susceptibility of all Salmonella isolates found will be determined by performing minimum inhibitory concentration tests using the National Antimicrobial Resistance Monitoring System Salmonella antibiotic panels. Salmonella spp. will be enumerated from hide and carcass samples using the methods under development in the Meats Research Unit at the U.S. Meat Animal Research Center. All Listeria isolates will be typed to identify the prevalence of common Listeria. A multiplex PCR will be used that will identify L. monocytogenes, L grayii, and L innocua, specifically, and L. seeligeri, L. weshmerii, and L. ivanovii as a group. A subsequent set of PCR reactions will be used to distinguish L. seeligeri, L. weshmerii, and L. ivanovii from one another (Bubert, 1999). Isolates of L. monocytogenes will be further serogrouped using a combination of molecular tests and specific antisera.