DIRECT-DETECTION AND ISOLATION OF PLASMID-BEARING VIRULENT SEROTYPES OF YERSINIA-ENTEROCOLITICA FROM VARIOUS FOODS

A procedure was developed for direct detection, isolation, and mainten ance of plasmid-bearing virulent serotypes of Yersinia enterocolitica from different food sources. Plasmid-bearing virulent strains of Y. en terocolitica representing five serotypes were simultaneously detected and isolated from enriched swab samples of artificially contaminated p ork chops, ground pork, cheese, and zucchini, using Congo red binding and low-calcium-response tests. The method was also effective in isola ting plasmid-bearing virulent strains of Y. enterocolitica from natura lly contaminated porcine tongues. Virulence of the strains isolated fr om these foods was confirmed by PCR, the expression of plasmid-associa ted phenotypes, and mouse pathogenicity.