Isolation of Yersinia enterocolitica and related species from river water.

One hundred and twenty samples of river water collected from sampling sites in the period between December 1986 and December 1987 were examined for the presence of Yersinia enterocolitica and related species. Among a total of 26 Yersinia strains isolated the following species were recognized: Y. enterocolitica, 12 strains, Y. intermedia, 5 strains, Y. frederiksenii, 2 strains, Y. kristensenii and Y. aldovae, 1 strain each; 5 were atypical Yersinia strains (rhamnose+, citrate+, alpha-methyl-D-glucoside+). Although the Yersinia isolates belong to the so-called "environmental" serotypes, which are usually considered as non-pathogenic for humans, Y. enterocolitica biotype 1, serotype 0:7.8, lysotype X0, which has previously been associated with gastro-intestinal infection in Italy, was found to be present. Statistical evaluation of our data showed that the presence of Yersinia spp. and the presence of total or fecal coliforms are unrelated.