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

The prevalence of yadA-positive Yersinia enterocolitica was determined in 1 85 pig tonsils from nine slaughterhouses using both the PCR and culture met hod. 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 sampl es, 20 were culture-negative, while of the 48 culture-positive, 16 were PCR -negative. Using the culture method, Y. enterocolitica belonging to the bio serotype 4/O:3 was found in 61 tonsils, of which 48 were yadA-positive. Typ e 4/O:3 was the only pathogenic bioserotype found in this study. Most of th e yadA-positive samples (85%) were recovered already after overnight enrich ment. A total of 61 isolates, including 13 yadA-negative isolates from diff erent samples, were characterized with PFGE. Using NotI and XbaI, 20 and 17 PFGE patterns were obtained respectively. Although the patterns were not i dentical most of them played only minor deviations. A total of 26 pulsotype s, defined by combination of the various Notl and XbaI digestion profiles, were observed. Two to eight different pulsotypes were observed in each slau ghterhouse 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 slaughter-houses. The pulsotype 1a was identified in eight o ut of nine slaughterhouses and the pulsotype 4g int seven slaughterhouses. (C) 2000 Academic Press.