[The occurrence of Yersinia enterocolitica in sewage].

Using a modified cold enrichment procedure Yersinia spp. were detected in 90.6% out of 32 raw waste water samples obtained within one year from two municipal sewage treatment plants. Moreover Yersinia were isolated from 50% of 6 effluent samples. Altogether 118 Yersinia strains were isolated and typed biochemically and serologically. 69 out of these isolates belonged to Yersinia enterocolitica, 60 strains to biotype 1, and 9 to biotype 4, serotype 0:3, 8 strains Yersinia enterocolitica serotype 0:3, biotype 4, considered to be a causative agent in human enteritis, harboured an 48 MD plasmid. The remaining isolates were identified as Yersinia frederiksenii (24 strains), Yersinia intermedia (22 strains) and Yersinia kristensenii (3 strains). The frequency of the isolation of Y. enterocolitica serotype 0:3, biotype 4 from sewage showed the same seasonal dependence as known from strains of human origin. In contrast to this, such dependence could not be found among other serovars of Y. enterocolitica and related species.