[The study of patterns of development of resistance of Staphylococcus aureus to triclosan].

The article presents the results of studying molecular genetic mechanisms of development of resistance to antiseptic Triclosan in strain Staphylococcus aureus АТСС25923. The modifcations of strain S. aureus АТСС25923 (Tr1, Tr2, Tr1С и Tr2С) are obtained resistant to 64 mg/l of Triclosan and stably preserving the given characteristic under cultivation in absence of selective pressure. The strain S. aureus Tr1was characterized by slightly delayed growth and the strain S. aureus Tr2 was characterized by growth velocity comparable with initial strain. In the Triclosan-resistant strains a mutation C284T in gene fabI was detected resulting in amino-acid replacement A95V in enzyme enoyl-acyl protein reductase FabI, triclosan target. Besides, in these strains a stably inheriting mutation was detected in genes associated with transport of substances in cell: hypothetical transport protein HlyC/CorC family transporter, protein-transporter of ions of Na+, K+, Li+ and alkali of Na+/H+ antiporter subunit F, membrane hypothetical protein and ATP-binding protein. It is demonstrated that resistance to triclosan in staphylococci is associated with acquirement of point mutations in genes of enoyl-acyl protein reductase and also in other genes related to transport of substances in bacterial cell.

[ON THE ORIGIN OF HYPERVIRULENCE OF THE CAUSATIVE AGENT OF PLAGUE].

The attempt to combine Yersinia pseudotuberculosis and Yersinia pestis into one species has been unsupported by microbiologists due to the specific features of the epidemiology and clinical presentations of their induced diseases and to basic differences in their virulence. Pseudotuberculosis is predominantly a relatively mild human intestinal infection transmitted through contaminated food and plague is an acute generalized disease with high mortality, which is most frequently transmitted by the bites of infected fleas. Y. pestis hypervirulence, the ability of single bacteria to ensure the development of predagonal bacteriemia in rodents, which is sufficient to contaminate the fleas, is one of the main events during pathogen adaptation to a new ecological niche. By analyzing the data of molecular typing of the representative kits of naturally occurring Y. pestis isolates, the authois consider the issues of formation of intraspecies groups with universal hypervirulence, as well as biovars that are highly virulent only to their major host. A strategy for searching for selective virulence factors, the potential molecular targets for vaccination and etiotropic treatment of plague, is discussed.