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T V Stepanova

Publications and source records attributed to T V Stepanova.

30 records · Page 2Linked to original sources
PubMedDate not supplied

[Influence of tumor necrosis factor on the growth of vegetative and nonculturable forms of Salmonella].

The growth rate of the vegetative forms and the recultivation rate of the uncultivable forms of Salmonella isogenous strains, one of these strains carrying mutation in gene pqi, were studied. The multiplication rate of the vegetative and uncultivable forms of Salmonella control strain in the spleen of infected animals at the initial stages of the infectious process was shown (in vivo) to be considerably accelerated after the preliminary incubation of the culture with cytokine (tumor necrosis factor). The multiplication rate, in vivo and in vitro, of Salmonella vegetative and uncultivable forms with mutation in gene pqi did not change after the incubation of the cells with cytokine, which is indicative of an important role played by the product of this gene in the process of the interaction of bacteria with cytokines. The full nucleotide sequence Salmonella gene pqi was determined.

Amino Acid Sequence↗
PubMedDate not supplied

[Virulent properties of hospital strains of bacteria of the Burkholderia cepacia complex, isolated in hospitals of Moscow].

The results of the study of hospital strains of the B. cepacia complex, isolated in hospitals of Moscow, with the use of phenotypical and molecular-genetic methods are presented. The phenotypical methods made it possible to differentiate Russian strains and classify them with a group of genomovars (I, III, IV). As the result the epidemic importance of the strains with epidemic markers, having specific characteristics for every clinic, was determined. The detection of the collection of genes cepI and cepR in the strains made confirmed the epidemic importance of the stains which had, due to the regulatory "quorum sensing" (QS) system, the potential capacity for inducing infection and persisting in the patient's body. The presence of gene cepR in all strains and the absence of gene cepl in 33% of strains gave evidence to suggest that in some strains the activation of the production of pathogenicity factors required the presence of other bacteria having the fully developed QS system. Thus, the new complex approach with the use of phenotypical and molecular-genetic methods permits more precise identification of the source of hospital infection induced by the bacteria of the B. cepacia complex.

Bacterial Proteins↗
PubMedDate not supplied

[Antibiotic sensitivity of Bacillus thuringiensis var. galleriae strains].

Bacillus thuringiensis strains forming colonies of the S and R morphology were found to be susceptible to streptomycin, chloramphenicol, rifampicin, neomycin, lincomycin, monomycin, kanamycin, and resistant to ampicillin and polymyxin. The S strains were shown to be susceptible to tetracycline (Tets), whereas the R strains were either susceptible (Tets) or resistant (Tetr). The population of Tetr strains was heterogeneous in its resistance to tetracycline (the frequency of Tetr cells was from 10(-4) to 1). The incubation with a subinhibiting concentration of tetracycline (2 micrograms/ml) caused "induction", which decreased in the presence of chloramphenicol, in the Tetr strains. No "induction" was detected in Tets strains. No significant differences were found in the plasmid composition of the Tets and Tetr strains, and no correlation was established between the presence of plasmids and the resistance to tetracycline. It may be concluded therefore that determinants for the resistance to tetracycline are located in the chromosomes. Possible factors causing the resistance to tetracycline in B. thuringiensis are discussed.

Anti-Bacterial Agents↗