Isolation of Yersinia enterocolitica from surface and well waters in Ontario

Yersinia enterocolitica was isolated from forty-three surface- and well-water samples and one municipal supply. In many cases these samples were negative for coliform bacteria. After incubation of membrane filters on M-Endo agar LES at 35 degrees C for total coliform analysis, filters were held an additional 24 h at room temperature. This method was more productive for isolation of waterborne types of Y. enterocolitica than was cold enrichment in buffer alone or in combination with modified Rappaport broth. Most of the water isolates were atypical in being rhamnose-positive. Eighteen isolates (38%) were serotypable, presenting nine different serotypes with 0:4 occurring most frequently followed by 0:6,30. Water isolates of serotype 0:6,30 resemble human strains of the same serotype.