OCCURRENCE OF VIRULENCE GENES AND BIOFILM FORMATION IN YERSINIA ENTEROCOLITICA ISOLATED FROM PIGS

Sixty isolates of Yersinia enterocolitica from pigs belonging to 1A and 4 biotypes, and one non-typeable isolate were investigated in order to determine the occurrence of genes directly connected with pathogenicity of Y. enterocolitica by using a multiplex PCR. The multiplex PCR assay was based on the amplification of the ail, ystA, ystB, and yadA genes in one reaction. The bacterial adhesion to hydrocarbon test was used to evaluate cells surface hydrophobicity of Y. enterocolitica. Assay of biofilm formation was performed with the use of polystyrene tissue culture plate. In all isolates (n=33) of biotype 1A and in biochemically not typeable isolate, the ystB-specific amplification product of 68 bp was obtained. In all isolates (n=26) of biotype 4, the specific PCR products for ystA gene and ail gene were obtained. In the majority of this biotype isolates (18/26) the specific PCR product for the plasmid yadA gene was detected. The percentage of isolates with hydrophobic surface of cells was 27.8% and 30.8% within biotype 1A and 4, respectively. All hydrophilic and hydrophobic isolates of Y enterocolitica adhered to polystyrene, although in different degree. These results suggest that cell-surface hydrophobicity is not important in Y. enterocolitica adhesion and subsequent biofilm formation. The multiplex PCR assay for simultaneous detection the ail, ystA, ystB and yadA genes, enabled fast evaluation of the potential virulence of isolates and differentiation of the pYV plasmid-bearing Y. enterocolitica isolates, the plasmidless isolates, and biotype 1A isolates.