MOLECULAR CHARACTERIZATION OF YERSINIA-ENTEROCOLITICA BY PULSED-FIELDGEL-ELECTROPHORESIS AND HYBRIDIZATION OF DNA FRAGMENTS TO AIL AND PYVPROBES

Sixty strains of Yersinia enterocolitica from five serogroups (O:3; O: 9; O:8; O:5; and O:5,27) and eight non-Y. enterocolitica strains, reco vered from diverse sources (humans, animals, food, and the environment ) in Europe, Argentina, and the United States, were examined by the pu lsed-field gel electrophoresis (PFGE) technique of contour clamped hom ogeneous electric field electrophoresis (CHEF) by using NotI and XbaI as restriction enzymes. NotI and XbaI generated 36 and 33 restriction endonuclease digestion profiles (REDP), respectively. By combining the results of both enzymes, 42 unique genomic groups were differentiated . DNA fragments were transferred to nylon membranes and hybridized wit h digoxigenin-labelled oligonucleotide probes to the ail gene and viru lence plasmid to determine hybridization patterns and the potential vi rulence of the strains. The strains were tested for the presence of th e plasmid by PFGE-CHEF and phenotypic characteristics encoded for by t he virulence plasmid. Thirty of the 60 Y. enterocolitica strains teste d harbored the virulence plasmid. The specificity of the ail and pYV p robes was 100% when tested with 68 Yersinia strains and 19 different n on-Yersinia strains. Sixteen selected Y. enterocolitica strains were t ested for their virulence by lethality in iron- and desferrioxamine-se nsitized mice. No correlation between REDP and the virulence of the st rains was observed. The observed REDP and the hybridization patterns w ere very homogeneous within a serogroup and independent of the source of isolation. In addition, PFGE-CHEF was shown to be valuable in ident ifying and confirming serogroups. Principal component analysis of Dice similarity indices from REDP was an excellent tool for determining ge netic relatedness among strains.