Nine strains of Yersinia species isolated from pigs and dogs in Korea, comprising 5 strains of Yersinia enterocolitica, 2 strains of Y. kristensenii and each strain of Y. pseudo-tuberculosis and Y. intermedia, were examined for the presence of virulence-associated plasmids, calcium dependency and provocation of guinea pig conjunctivitis (Sereny test). Three strains of Y. enterocolitica isolated from pigs were positive in calcium dependency and harbored one plasmid of about 45 megadalton, but negative in Sereny test

To investigate the epidemiological trait of intestinal diseases of animals caused by thermophilic Campylobacter spp., isolation of etiological agent was carried out and the profiles of plasmids and the transfer of resistance plasmid in the isolated Camplyobacter spp. were examined. A total of 110 isolates of C jejuni and C coli were subjected to the test for the presence of plasmid DNA. Of the isolates examined, 60 % of the isolates were noted to harbor plasmid DNA. Plasmid occurrence rate from pigs, chickens and cattle were 76.2 %, 61.7 % and 37.7 %, respectively. The plasmids of a large molecular weight, ranging from 36 Md to 86Md, were identified with the strains of tetracycline resistant. Transfer frequency of tetracycline resistant plasmids was higher in the case of the filter mating method than in the broth mating method by the factor of 10-1,000. Tetracycline resistant plasmids of C jejuni were transferarble to C jejuni and C coli by conjugation. In a low frequency, the transfer of tetracycline plasmid was also possible to Vibrio parahemolyticus. However, it was impossible to transfer to Streptococcus fecalis, E. coli and Vibrio cholerae. Tetracycline resistant plasmids of C jejuni were impossible to transfer to Campylobacter spp. and related bacteria by transformation