Prevalence ofSalmonellaspp andYersinia enterocoliticain slaughtered pigs: molecular typing, virulence profile and antimicrobial resistance

The prevalence and the sources ofSalmonella entericaandYersinia enterocoliticaat slaughterhouse in Sardinia were investigated and the isolates characterized.Salmonellawas isolated from colon content (15%), lymph nodes and liver (12.7%) and carcass surface (11%). 28 pigs wereSalmonellacarriers in lymph nodes and/or colon content and 10 were also positive at carcass level. 69Salmonellastrains were isolated and 7 serovars identified, the most common being Anatum (41%), Rissen, Derby (19.0%), 1,4,[5],12:i:-: (15.9%). N.33Salmonellastrains were found to be resistant to more than one antimicrobial. PFGE permitted the resolution ofXbaImacrorestriction fragments ofSalmonellastrains in 11 pulsetypes.Y. enterocoliticacontamination level detected with cultural method in tonsils (3.8x103CFU/g) represents a possible risk for carcasses and fresh pork meat. The most commonY. enterocoliticabioserotype 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 onY. enterocoliticastrains using the NotI enzyme, yelded 7 different PFGE patterns. To reduceSalmonellaandY. enterocoliticaprevalence 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).