Prevalence and characterization of pathogenic Yersinia enterocolitica in pig tonsils from different slaughterhouses

Abstract

The prevalence of yadA-positive Yersinia enterocolitica was determined in 185 pig tonsils from nine slaughterhouses using both the PCR and culture method. The mean prevalence was 37%, varying from 13% to 45% when both PCR and culture-positive results were included. Of the 52 PCR-positive tonsil samples, 20 were culture-negative, while of the 48 culture-positive, 16 were PCR-negative. Using the culture method, Y. enterocolitica belonging to the bioserotype 4/O:3 was found in 61 tonsils, of which 48 were yadA-positive. Type 4/O:3 was the only pathogenic bioserotype found in this study. Most of the yadA-positive samples (85%) were recovered already after overnight enrichment. A total of 61 isolates, including 13 yadA-negative isolates from different samples, were characterized with PFGE. UsingNotI and XbaI, 20 and 17 PFGE patterns were obtained, respectively. Although the patterns were not identical, most of them played only minor deviations. A total of 26 pulsotypes, defined by combination of the various NotI andXbaI digestion profiles, were observed. Two to eight different pulsotypes were observed in each slaughterhouse, The most common pulsotypes, 1a and 4g, were found in 36% and 20% of the tonsils, respectively and these pulsotypes were widely distributed to most of the slaughterhouses. The pulsotype 1a was identified in eight out of nine slaughterhouses and the pulsotype 4g in seven slaughterhouses.