The design, validation and clinical verification of an in-house qualitative PCR to detect Yersinia enterocolitica and Yersinia pseudotuberculosis in faeces.

Yersiniosis is a zoonotic foodborne infection of public health significance. The aim of this study was to design and validate a simple, accurate and cost-effective polymerase chain reaction (PCR) to detect pathogenic Yersinia spp. in faecal samples. An intercalating dye (EvaGreen)-based real-time multiplex PCR assay was designed to detect yadA, ystB and inv by melt curve analysis, allowing undifferentiated detection of all Yersinia enterocolitica biotypes, including biotype 1A, and Yersinia pseudotuberculosis. The assay was validated using cultured bacteria and clinical samples. A total of 107 positive and 51 negative samples were tested. The sensitivity and specificity was 98% and 100%. The limit of detection was 104-105 CFU/g faeces. A total of 605 samples (9 positive) were tested in the clinical verification with an accuracy and negative predictive value of 99% [95% confidence interval (CI) 97.9-99.6%] and 99.8% (95% CI 97.9-99.6%), respectively. This is an accurate, simple and cost-effective assay for the detection of pathogenic Yersinia spp.