SCREENING OF PATHOGENIC AND NONPATHOGENIC YERSINIA STRAINS FOR THE PRESENCE OF CHROMOSOMAL VIRULENCE MARKERS

Pathogenicity of Yersinia strains is determined by the presence of plasmid and chromosomal encoded virulence factors. Chromosomal genes inv and ail, encoding proteins that enable the bacterium to adhere to and invade eukaryotic cells, genes for iron acquisition (irp-genes), genes responsible for synthesis of O-antigen of lipopolysaccharide (wzz, wzy, etc.) and the enterotoxin gene yst are well studied. In the recent work the presence of some chromosomal virulence markers in pathogenic and nonpathogenic Yersinia strains, such as irp-genes from the high pathogenicity island, yst-gene required for the synthesis of heat-stable enterotoxin, as well as the protease production responsible for the caseinolytic activity were studied. Irp positive were pathogenic and nonpathogenic Y. enterocolitica strains of biotype 1A, Y. pseudotuberculosis strains, but not environmental Yersinia ones. Yst-gene was, detected at some Y. enterocolitica and Y. pseudotuberculosis strains, as well as in nonpathogenic Y. kristensenii and Y. bercovieri strains. The same strains were tested for protease production. Low pathogenic Y. enterocolitica, serotype O:5 and nonpathogenic Y. kristensenii and Y. frederiksenii were positive. We did not establish a correlation in distribution of the screened chromosomal markers. Our results show that all studied virulence markers arc, not suitable for detection and differentiation of pathogenic from nonpathogenic Yersinia strains.