Prevalence of <i>Salmonella</i> spp and <i>Yersinia enterocolitica</i> in slaughtered pigs: molecular typing, virulence profile and antimicrobial resistance

The prevalence and the sources of Salmonella enterica and Yersinia enterocolitica at slaughterhouse in Sardinia were investigated and the isolates characterized. Salmonella was isolated from colon content (15%), lymph nodes and liver (12.7%) and carcass surface (11%). 28 pigs were Salmonella carriers in lymph nodes and/or colon content and 10 were also positive at carcass level. 69 Salmonella strains were isolated and 7 serovars identified, the most common being Anatum (41%), Rissen, Derby (19.0%), 1,4,[5],12:i:-: (15.9%). N.33 Salmonella strains were found to be resistant to more than one antimicrobial. PFGE permitted the resolution of XbaI macrorestriction fragments of Salmonella strains in 11 pulsetypes. Y. enterocolitica contamination level detected with cultural method in tonsils (3.8x103CFU/g) represents a possible risk for carcasses and fresh pork meat. The most common Y. enterocolitica bioserotype was 4/O:3 (68.8%). The most common virulence-associated gene in 4/O:3 isolates was the ysta (97.0%,), followed by ail (84.8%) and inv (78.8%,). PFGE performed on Y. enterocolitica strains using the NotI enzyme, yelded 7 different PFGE patterns. To reduce Salmonella and Y. enterocolitica prevalence some preventive measures should be encouraged: the identification of origin of infected slaughtered animals should be performed, and the direct and cross-contamination of carcasses avoided according to HACCP principles in association with good hygiene procedures (GHP)