Results strongly suggest that there is a high prevalence of Salmonella spp in cull dairy cows at slaughter, which could burden Hazard Analysis Critical Control Point programs implemented in slaughter establishments. Procedures to reduce Salmonella load at the dairy farm and during transport to slaughter could reduce the risk of spread during the slaughter process.
58 Salmonella serotypes were isolated from market dairy cows at slaughter and could pose a threat for food-borne illness. Salmonella Montevideo was the most frequently isolated serotype and may contribute substantially to salmonellosis in dairy cattle.
Vibrio vulnificus contamination of raw oysters is a serious public health hazard, therefore, it is necessary to investigate the persistence of V. vulnificus in harvested and stored oysters. For this study, triplicate oyster samples were split into four treatment groups: control, normal-packaged; control, vacuum-packaged; inoculated, normal-packaged; and inoculated, vacuum-packaged. Oysters in the inoculated groups were individually injected with V. vulnificus to a level of approximately 1 × 106 CFU/g. Control oysters were already naturally contaminated to a level of approximately 1 × 104 CFU/g. Oysters were then packaged, frozen and stored at −20°C. On day 0 and days 7, 14, 30 and 70 post-freezing, concentrations of total aerobic bacteria and V. vulnificus were determined using a 3-tube most probable number (MPN) estimation from enrichment Alkaline Peptone Water tubes with subsequent presumptive V. vulnificus growth on modified Cellobiose-Polymyxin B-Colistin agar. Length of frozen storage had a significant effect on decreasing total aerobic bacteria (from approximately 106 CFU/g to approximately 102.5 CFU/g) and V. vulnificus (from approximately 105 CFU/g to approximately 101 CFU/g). Also, vacuum-packaged samples showed significantly lower concentrations of V. vulnificus over the length of the study than did the normal-sealed samples.
Tissues from animals slaughtered at the university abattoir were sampled to determine the spread of bacterial contamination during slaughter. Salmonellae and coliform organisms were cultured from swabs taken of the equipment before and during slaughter and from various viscera sites during slaughter.
Since salmonellae isolations were expected to be low, coliforms were used as an index of contamination. The study indicated that equipment was satisfactorily sanitized before slaughter and minimal contamination occurred during slaughter except for the viscera pans. Contamination of the viscera and carcass of cattle, swine, and sheep was very high. It was found that the bung-dropping operation is less of a contaminating factor than is generally thought and that washing the carcass after evisceration is probably responsible for the greatest spread of contamination.
Salmonellae were isolated from only two swine. The patter of contamination spread was similar to that of coliforms.
Yersinia enterocolitica serotype 0:5 was isolated from the tonsils of 8 of 27 butcher hogs subjected to normal slaughtering procedures. Isolation through enrichment in cold mannitol broth or a bile medium at 4 C for 10–60 days was equally effective. Enrichment in modified Rappaport broth at 25 C for longer than 2 days sharply decreased recovery of Y. enterocolitica from tonsils. The type of enrichment medium also had a marked effect on the recovery efficiency of different strains of Y. enterocolitica from ground meat.
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