[Development of molecular PCR-RFLP test for identification of the epidemic strain of Y. enterocolitica bioserotype 1B/O8 circulating in Poland since 2004].

Introduction: Highly pathogenic Y. enterocolitica bioserotype 1B/O8 is considered to be an important etiological agent of yersiniosis in Poland. Infections caused by Y. enterocolitica 1B/O8 became an important public health problem in Poland, especially because of their high potential of virulence and the unknown source of the bacteria. Y. enterocolitica 1B/O8 isolates recovered in Poland are genetically highly related and constitute single epidemic sensu stricto strain. The aim of the present study was to develop a time- and money-effective molecular assay for rapid identification of pathogenic Y. enterocolitica 1B/O8 isolates belonging to the epidemic strain.

Methods: In the first stage we performed a multiplex-PCR for four genetic markers: ail, ystA, irp1 and 16S rDNA sequence. In the next stage we designed a duplex-PCR-RFLP assay with BtsI endonuclease to detect/identify specific variant of an ysrR gene that is characteristic for epidemic strain of Y. enterocolitica 1B/O8 strain. The assay was tested against a panel of a consisted of a variety Yersinia enterocolitica and Y. pseudotuberculosis strains.

Results: All the tested Y. enterocolitica 1B/O8 strains were positive for all the genetic markers in multiplex-PCR assay what distinguished them from other tested Yersinia strains. In duplex-PCR-RFLP test all tested isolates of the epidemic strain were negative for ysrR digestion with BtsI endonuclease, while all tested reference strains of Y. enterocolitica 1B/O8 were positive.

Conclusions: The assay developed in this study was two-stage/two-step molecular test efficiently distinguishing wild-type and the epidemic Y. enterocolitica 1B/O8 strain. Such test can be a useful screening tool for clinical, veterinary and food diagnostics, as well as for the purposes of epidemiological investigation.