BIOMOLECULAR CHARACTERISTICS OF YERSINIA PSEUDOTUBERCULOSIS AND YERSINIA ENTEROCOLITICA ISOLATED IN SIBERIA AND IN THE FAR EAST

A special feature of Y. pseudotuberculosis strains is its biochemical uniformity irrespective of the time and location of the causative agent isolation and the existence of 21 serological variants. Y. enterocolitica is a quite a heterogeneous species and is classified into 6 biochemical types associated with 29 serological variants. 221 Y. pseudotuberculosis and 447 Y. enterocolitica strains in total isolated in Siberia and in the Far East were characterized. Y. pseudotuberculosis genotype dominating in the Siberian and Far Eastern regions is presented by О:1b serotype of the first genogroup (pYV+, ympA+, HPI-) in two- (47:82 МDа) or single-plasmid (47 МDа) variants. Ribotyping and fingerprinting revealed 8 and 10 Y. pseudotuberculosis genotypes, respectively, that indicated relative heterogeneity of the circulated strains. Regional difference of ribotypes and fingerprints was noted. 401 of 447 Y. enterocolitica strains were classified as biotype A1 including 11 serotypes (O:4,32; O:4,44; O:5; O:6,30; O:6,31; O;7,8; O:12,25; O:13,7; O:19,8; O:41,43) and 46 strains belonged to biotypes 2–4 of O:3 and O:9 serotypes. Y. enterocolitica strains of biotypes 1A were isolated both from the environments, animals and patient samples as like the representatives of biotypes 2–4. The differentiating tests of fucose and sorbose made it possible to identify two species new for the Russian Federation – Y. mollaretii and Y. bercovierii. Y. enterocolitica biotypes 2–4 carried pYV plasmid and chromosomal ail, ystA virulence genes. These strains were referred to phagotypes Х3 (2/O:9) and VIII (4/O:3) and also to phagotype Xz (3/O:3), unique for Russia. Y. enterocolitica biotype 1A containing ystB thermostable toxin gene was confirmed to be an infectious etiological agent.