Detection of pathogenic Yersinia enterocolitica in milk and pork using a DIG-labelled probe targeted against the yst gene

A PCR-amplified, digoxigenin (DIG)-labelled yst probe was evaluated in naturally and artificially contaminated pork and milk samples for its ability to detect and differentiate between pathogenic and nonpathogenic strains of Yersinia enterocolitica following enrichment in irgasan-ticarcillin-chlorate (ITC) enrichment broth. A total of 44 raw pork samples were obtained from one meat-processing factory and two local retail stores. Y. enterocolitica serogroup O:3/biovar 4 was isolated from 6 of the 44 (14%) pork samples tested. The hybridization results were in good agreement when compared with those from standard biochemical and serological tests. The lowest concentration detectable by a colony hybridization technique in the milk samples inoculated with Y. enterocolitica O:8 PA-A corresponded to 10 cfu/ml in the original sample. No pathogenic serovars were detected in 6 raw milk and 3 pasteurized milks tested. The results of this investigation demonstrate that the DIG-labelled yst probe is a reliable tool for rapid detection of pathogenic Y. enterocolitica in naturally and artificially contaminated food samples.