Low occurrence of pathogenic Yersinia enterocolitica in pig tonsils at slaughter in Southern Brazil

Yersinia enterocolitica is a foodborne pathogen and pigs are the main reservoir of it in their tonsils. As Brazil is a large producer and exporter of pork meat and information regarding this pathogen is still quite scarce, this study aimed at evaluating the direct detection of Y. enterocolitica followed by pathogenic Y. enterocolitica (PYE) determination in tonsils of slaughtered pigs. For this purpose, 400 pig tonsils were collected from 15 farms in four federally certified slaughterhouses in Southern Brazil. Initially, samples were screened using conventional PCR targeting of the 16sRNA gene, followed by multiplex PCR (mPCR) in order to detect three virulence genes (ail, yadA, and virF) and quantitative real-time PCR (qPCR) for the detection of the ail gene. One hundred and one (25.2%) of the samples tested positive for the 16sRNA gene. However, a PYE was detected in one out of the 101 Y. enterocolitica positive samples. The three virulence genes were determined by mPCR and confirmed by partial DNA sequencing. Thus, a significant occurrence of Y. enterocolitica was observed in pig tonsils from federally inspected slaughterhouses in Brazil, although the presence of pathogenic strains was quite low.