RESUMO
A 145 base pair digoxigenin-d-UTP-labelled probe, specific for pathogenic Yersinia enterocolitica heat-stable enterotoxin yst gene, was prepared by PCR. The probe was used in DNA-DNA colony hybridization and dot-blot hybridization assays. The specificity of the probe was confirmed using 52 strains representing all Yersinia spp., except Y. pestis. Out of a total of 25 Y. enterocolitica strains screened, the probe correctly identified all 18 pathogenic strains. Among the other Yersinia spp. screened, only one strain of Y. kristensenii was positively detected by the yst probe but could be differentiated by its weak signal response as compared with that obtained by pathogenic strains of Y. enterocolitica.
Assuntos
Toxinas Bacterianas/genética , Sondas de DNA , Enterotoxinas/genética , Genes Bacterianos , Yersinia enterocolitica/patogenicidade , DNA Ribossômico/genética , Digoxigenina , RNA Ribossômico 16S/genética , Sensibilidade e Especificidade , Yersinia enterocolitica/classificação , Yersinia enterocolitica/genéticaRESUMO
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.
