[Invasiveness characteristics of the causative agent of pseudotuberculosis].

The comparative characteristics of the invasiveness of Y. pseudotuberculosis, the most important element of its pathogenicity, is given on the basis of the results obtained in testing 57 Y. pseudotuberculosis strains and 23 Y. enterocolitica strains, all of them recently isolated, on experimental models (the monolayer cultures of Hep-2 cells, the enteral inoculation of mice and guinea pigs, the keratoconjunctival test). The invasiveness of Y. pseudotuberculosis has been shown to be manifested immediately after the ir adhesion and accompanied by the multiplication of these microbes in the cytoplasma of Hep-2 cells and, in animal experiments, in the cytoplasma of the epithelial cells of mucous membranes and the macrophages of lamina propria mucosae. The intracellular multiplication leads to the destruction of the layer of Hep-2 cells and, in animal experiments, to the disintegration of the infected cells, the development of Hep-2 cells and, in animal experiments, to the disintegration of the infected cells, the development of erosions and ulcers, purulent lymphadenitis of the regional lymph nodes, generalized infection with multiple abscesses in internal organs. Y. enterocolitica strains under investigation induced neither conjunctivitis, nor enterocolitis in the animals, and in experiments on Hep-2 cells, these strains, having less pronounced adhesive properties, either showed sharply limited adhesiveness without the capacity for intracellular multiplication and cytotoxicity, or proved to be absolutely noninvasive.