Listeria monocytogenes, Yersinia enterocolitica, and Salmonella in dairy plant environments.

In order to determine the presence of the three environmental pathogens in dairy plants, six milk and four ice cream plants in a three state area were sampled. A total of 353 environmental samples were taken over three replications. Bacterial counts were performed on the environmental samples for chi-square analysis. Salmonella spp. were not isolated from any of the environmental samples. Yersinia enterocolitica was isolated from 6.8% of the environmental samples. Listeria monocytogenes was isolated from 6.5% of the environmental samples. Listeria spp. other than L. monocytogenes were isolated from 9.3% of the environmental samples. The presence of Y. enterocolitica was significantly related to high bacterial counts for six microbiological tests. The presence of L. monocytogenes was not related to high bacterial counts.