[Isolation and characterization of Yersinia enterocolitica from pigs and bovines in Chile]

The occurrence of Yersinia enterocolitica in tonsils and rectal swabs from 100 healthy pigs and the rectal swabs of 100 healthy cattle slaughtered at Santiago-Chile were analysed. Yersinia enterocolitica was isolated from 48 (48%) pigs but not from cattle. 98.2% of strains were of 4/O3 bioserogroup, considered to be pathogenic for humans. All of the strains were resistant to penicillin producing beta-lactamase. Most of them were resistant to neomicin and tetracycline. The pYV marker was used to demonstrate pathogenicity in all strains by four different assays: 65.5% of the strains were pYV positive by their plasmid profile; 73.3% by crystal violet binding; 84.5% by calcium dependency and 87.9% by hybridization with probe associated with cytotoxicity to Hep-2 cells in vitro. All of the Yersinia enterocolitica strains were pYV positive with at least one of the four tests analysed, 46/58 strains were positive by three tests simultaneously. The similarities between associated cytotoxic genes of porcine and human strains is discussed. The phenotypic and genotypic characteristics demonstrated by the isolates strains suggest that the pigs in Chile are reservoir of potential pathogenic Yersinia enterocolitica for humans.