Isolation of Yersinia enterocolitica and related species from porcine samples obtained from an abattoir

Abstract

Swabs of swine carcasses and samples of porcine tongue and trim obtained from an abattoir were examined for the presence of Y. enterocolitica and related species (Y. intermedia, Y. kristensenii and Y. frederiksenii). Three enrichment media (PO43- buffered saline, sorbitol-bile salts-PO43- buffered saline and a modified Rappaport''s broth) were compared at 4.degree. C for their efficiency of recovery of Y. enterocolitica and related species. Two secondary enrichment procedures (post-enrichment in modified Rappaport''s broth for 2 days at 25.degree. C and treatment with 0.5% KOH in 0.5% NaCl) also were evaluated. The porcine isolates were characterized by biochemical and serological examination, speciation and biotyping. Of 43 samples, 8 were positive for Y. enterocolitica and related species. The combination of incubation in sorbitol-bile salts-PO43- buffered saline for 21 days at 4.degree. C followed by post-enrichment in modified Rappaport''s broth yielded maximum number of isolates. All isolates, except one, were avirulent as determined by autoagglutination, Ca-dependence at 37.degree. C and HeLa [human cervical carcinoma] cell invasiveness tests.