This project provides comprehensive information on the levels and prevalence of Salmonella on pork carcasses during processing to benchmark the effectiveness of in-plant interventions on Salmonella reduction. During this project, 190 pork carcasses were sampled over two consecutive days in each of four seasons at a pork processing plant in the United States. Samples were collected at three steps in processing: skin (after exsanguination and before scalding), pre-evisceration carcass (after scalding, singeing, and polishing) and chilled final carcass in the cooler. Overall prevalence of Salmonella on skins was near 100% in all seasons with a one-day low of 85% in the winter. The range of Salmonella prevalence on pre-evisceration carcasses was between 10.5% and 69.5%. Final carcasses had 12.6% Salmonella prevalence in the summer, undetectable (0% prevalence) in the fall, ~4.2% prevalence in the winter and ~9% in the spring. The prevalence of Salmonella was twice as high on skins and three times higher on pre-evisceration and final carcasses as was expected. During the four seasons, the lowest enumerable level of Salmonella bacteria on skins was 27 cfu/100cm2 and the highest level was 2322 cfu/100cm2. Salmonella serotype and drug resistance patterns have been determined for 2,176 isolates. From this data set, 22 serotypes have been identified and the antibiotic profiles of these range from having resistance to eight antibiotics to being susceptible to all 14 antibiotics tested. When the amount of Salmonella on skins was high, as indicated by both a large number of enumeration positive samples and high enumeration levels, the chance of having Salmonella on carcasses was higher. However, the percentage of carcasses with levels high enough to enumerate and the enumeration levels were both relatively low.
Michael N. Guerini, Ph.D. USDA-ARS-USMARC, P.O. Box 166, Clay Center, NE 68933, (402)762-4226, [email protected]
