Resumo

Introduction: Yersinia frederiksenii, Yersinia intermedia and Yersinia kristensenii among other Yersinia enterocolitica-like species are little studied because they are considered, mainly, non-pathogenic strains. However, data suggest that some of Yersinia enterocolitica-like can cause disease and can express some genes involved in the Yersinia spp. pathogenesis. In this work, we aimed to evaluate the pathogenic potential of 118 Y. enterocolitica-like strains isolated from several sources in Brazil for 18 years. Materials and methods: A total of 50 Y. frederiksenii isolated from food (37), environment (10), animal (1) and human (2), 55 Y. intermedia isolated from food (34), environment (19), animal (1) and human (1) and 13 Y. kristensenii isolated from food (9), environment (3) and animal (1) were studied. The presence of ail, inv, ystA, ystB, fepA, fepD, fes, hreP, myfA, tccC and virF genes was searched by PCR. The amplifications were performed with 50ng of DNA template, each dNTP at 0.2mM, 4mM MgCl₂, 1U Recombinant Taq DNA polymerase, 1X PCR buffer and 25pmol of foward and reverse specific primer for each of the 11 genes. The PCR conditions were: 5 min at 94°C, 30 cycles consisting of 45 s to 94°C, 45 s at annealing temperature for each gene and 1 min at 65°C and final extension of 15 min at 65°C. The annealing temperatures were 45°C, 50°C, 45°C, 45°C, 45°C, 45°C, 60°C, 55°C, 50°C, 45°C and 50°C for ail, inv, ystA, ystB, fepA, fepD, fes, hreP, myfA, tccC and virF, respectively. The PCR products were analyzed for the presence or absence or bands by agarose gel electrophoresis and visualized under UV light after staining the gel with ethidium bromide. Results: Some Y. frederiksenii strains studied presented fepA (44%), fes (44%), ystB (18%) and virF (6%) genes. Some Y. intermedia strains studied presented ail (53%), fepA (35%), fepD (2%), fes (97%), inv (4%), hreP (2%), ystB (2%), tccC (35%) e virF (6%) genes. Some Y. kristensenii strains studied presented the ail (62%), inv (77%), ystB (23%), fepA (77%), fepD (54%), fes (54%) and hreP (54%) genes. Conclusion: The presence of ail, inv, ystB, fepA, fepD, fes, hreP, tccC and virF genes in Y. enterocolitica-like strains shows the possible pathogenic potential of some of these strains.