Forty‐eight isolates obtained from pasteurized milk and cream, raw milk, and various sites on a dairy farm were identified as Yersinia enterocolitica biotype 1 but were unusual in their ability to ferment lactose. The majority belonged to serotype 5a. Serotypes 5b, 6, 13/15 and 23/15 were also found. A few isolates were not typable. There is no evidence that strains isolated in this study are pathogenic for humans. Their presence in pasteurized products and growth at refrigeration temperatures are, however, cause for concern. Copyright © 1979, Wiley Blackwell. All rights reserved
