Submitted to: International Symposium on the Epidemiology and Control of Foodborne Pathogens in Pork
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2003
Publication Date: 10/1/2003
Citation: O'CONNOR, A.M., GRAY, J.T., HURD, H.S., MCKEAN, J.D., ROSTAGNO, M.H. GENETIC RELATEDNESS OF SALMONELLA FROM PENS AND SWINE AT SLAUGHTER. Proceedings of the International Symposium on the Epidemiology and Control of Foodborne Pathogens in Pork. 2003. p. 78-80. Interpretive Summary:
Technical Abstract: In previous studies we have reported recovering isolates of the same Salmonella serovar from swine and the pen used to hold those swine. This suggests that swine were rapidly infected during lairage. However, serotyping is only one method of categorizing Salmonella, and pen-pig matches between serovars may not be the same strain. This study presents the pulse-field gel electrophoresis (PFGE) genotyping of the isolates obtained in a previous study. Twenty-four (24) loads of pigs delivered to two abattoirs were studied. Swab samples were collected from the pen floor before placement of pigs. After 2-4 hours holding, cecal contents and ileocecal lymph nodes swine were collected post-harvest. Isolates representing a pen-pig serovar match were selected for (PFGE) genotyping. Based on PFGE pattern, isolates were assigned to clusters with 100% homology. A total of 229 isolates were genotyped (51 isolates from pens and 178 isolates from pigs). Overall, 90 PFGE patterns (clusters) were identified. Of these 90 clusters, only 6 exhibited pen-pig matching (50 isolates). The serovar distribution of those 50 isolates was: 27 Anatum, 11 Typhimurium, 8 Derby, and 4 Heidelberg. For Anatum, 38% (27/70) of all recovered Anatum belonged to pen-pig matched clusters, whereas for the remaining serovars the distribution was: 33% (4/12) of Heidelberg, 23% (11/46) of Typhimurium, 10% (8/82) of Derby, 0/12 of Infantis, and 0/7 of Saint-Paul. This study further supports the concept that pre-slaughter holding pens constitute an important S. enterica infection source for pigs. Additionally, some serovars seem to be more able to rapidly infect or contaminate the gastrointestinal tract of exposed pigs. And, it also seems that the ability to rapidly infect or contaminate the exposed animals may vary within a serovar group. These findings may help explain why some S. enterica serovars are prevalent in swine, but not in human salmonellosis.