Characteristics of Yersinia enterocolitica and related species isolated from human, animal, and environmental sources.

During a 4-year period, 4,448 human, animal, and environmental samples collected in New York State were tested for the presence of Yersinia enterocolitica or related species. A total of 339 isolates were identified as Yersinia and characterized according to source, species, biogroup, serogroup, and, in some instances, phage type. Four new biogroups of Y. intermedia were characterized. Of 149 human isolates, 120 (80.5%) were identified as Y. enterocolitica, and 29 were identified as either Y. intermedia (12.1%), Y. frederiksenii (5.4%), or Y. kristensenii (2.0%). Of the other 190 isolates, recovered from animals and the environment, 54 (28.4%) were Y. enterocolitica and 136 were either Y. intermedia (62.6%), Y. frederiksenii (4.7%), Y. kristensenii (3.7%), or an undescribed Yersinia species (0.5%). Two established human pathogenic strains of Y. enterocolitica were recovered: 59 isolates (37 from an outbreak) of "American strain" (serogroup O:8, biogroups Niléhn 2, Wauters 1, and Knapp and Thal 2, phage type Xz) and 11 isolates of "Canadian strain" (serogroup O:3, biogroups Niléhn 4, Wauters 4, and Knapp and Thal 1, phage types IXb). This was the first documented isolation of the Canadian strain in the United States. Isolates of other strains implicated in human disease (serogroups 0:4,33, 0:5, O:6,31, O:7,8, and O:8) were also recovered from both human and nonhuman sources.