Structural variability of 40-50 Mdal virulence plasmids from Yersinia enterocolitica. Geographical and ecological distribution of plasmid variants.

Restriction endonuclease analysis (BamHI and EcoRI) was used to investigate the structural variability of 40-50 Mdal plasmids from 129 Yersinia enterocolitica strains isolated from human patients, animals, and food in 12 countries in Europe, North America, and Asia. A total of 12 restriction patterns was detected among plasmids from the six serogroups examined. The DNA fragment profiles were found to vary, not only between serogroups, but also among plasmids isolated from strains with the same serogroup affiliation. Despite widespread geographical and ecological origin, the plasmids isolated from the 0:3 and 0:9 strains examined revealed a surprising stability, whereas plasmids from 0:8 and 0:5,27 showed substantial diversity. The genes associated with autoagglutination, calcium dependency, and mouse virulence were conserved in all 12 plasmid variants detected. Our finding that porcine and human isolates harboured plasmids with identical restriction patterns, provides additional support for the importance of pigs in the epidemiology of human Y. enterocolitica infection.