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V I Pushkareva

Publications and source records attributed to V I Pushkareva.

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

[The interrelationships between Vibrio cholerae and the infusorian Tetrahymena pyriformis].

The results of the study of interaction between V. cholerae of different virulence and T. pyriformis are presented. The study has revealed the heterogeneity of V. cholerae population: alongside easily phagocytized vibrios, there are vibrios resistant to the digestive action of T. pyriformis. An increase in the number of V. cholerae in association with T. pyriformis has been evaluated, taking into account the selective multiplication of vibrios resistant to phagocytosis. The data on changes in the agglutinative, phagolytic and virulent properties of V. cholerae cultivated together with T. pyriformis are presented. The suggestion has been made that protozoa can function as hosts of pathogenic vibrios supporting their existence in water.

Animals↗
PubMedDate not supplied

[Bacterial pathogenicity factors: their functions in the environment].

On the basis of literature data and the results of experimental studies the concept of the universal character of the main pathogenicity factors of bacteria (adhesion, enzymes, toxins, resistance to phagocytosis) as the adaptive mechanisms of bacterial populations under different ecological conditions, including their existence in the environment, has been put forward. Resistance of bacteria to phagocytosis as the mechanism of their protection from predators (protozoa, etc.), necessary for the existence bacteria in the ecological systems of water and soil, is considered in detail.

Adaptation, Physiological↗
PubMedDate not supplied

[Potential hosts and routes of the circulation of Yersinia pseudotuberculosis in an aqueous ecosystem].

The interaction between Y. pseudotuberculosis and different representatives of the aqueous and, partially, soil biocenosis was studied. The study revealed that invertebrates of the plankton and benthos (water fleas, cyclops, mollusks, Oligochaeta, larvae of insects), as well as fish and higher plants, ensured the prolonged existence of Yersinia in water. Thus hydrobiotic organisms were to be regarded as potential natural hosts of Y. pseudotuberculosis. A suggestion was made that fish, the final link of some alimentary chains, could present epidemic danger as a food product for human consumption.

Animals↗
PubMedDate not supplied

[Listeria in plants: an experimental study of its colonization, numbers and variability].

The possibility for Listeria monocytogenes to penetrate into plants from the soil via the root system was experimentally proved. Listeria were shown to continuously persist for 30 days (the term of observation) in the vegetative organs of wheat (roots, stems and leaves). The concentration of Listeria was 10(9) CFU/g in the environment (soil extract) and the roots of wheat, 10(6)-10(7) CFU/g in stems, 10(8)-10(9) CFU/g in leaves. Six days later the dissociation of colonies in the S-form into small (up to 1 mm) and large (3-4 mm) was observed; in contrast to Listeria in large colonies, those in small colonies had high catalase activity and pronounced cytopathogenic action. The problem of the possible role of plants as the natural reservoir of bacteria, pathogenic for humans and animals, is discussed.

Catalase↗
PubMedDate not supplied

[Pathogenic Listeria in the soil and in association with algae: a reversible transition into a nonculturable state].

The analysis of the dynamics of the amount of L. monocytogenes in soil extract in association with green algae and in their absence, carried out in parallel by the bacteriological method and in polymerase chain reaction (PCR), revealed the mass transition of L. monocytogenes into the nonculturable state. The proportion of vegetative (bacteriologically detected) forms in the bacterial population rapidly decreased, while its total amount remained unchanged due to the formation of inactive (nonculturable) L. monocytogenes forms. Algae or their metabolites considerable accelerated this process: by day 26 L. monocytogenes could not be isolated, but in PCR they could be registered at their initial concentration: 10(6) microbial cells/ml. Inactive L. monocytogenes forms were shown to revert into the vegetative (culturable) state under the action of fetal serum, live and killed infusoria, auxin. The concentration of revertants grown on a solid culture medium was high: 10(4)-10(5) colony-forming units/ml.

Bacteriological Techniques↗
PubMedDate not supplied

[The possibility of preserving the causative agent of plague in soil in resting (nonculturable) form].

The parallel study of soil specimens from the burrows of great gerbils, taken in the natural focus of infection at the period between epidemics, by the bacteriological method and with the use of polymerase chain reaction (PCR) demonstrated that, simultaneously with the negative results of inoculations into nutrient media, PCR revealed the presence of Y. pestis in 4 out of 72 soil specimens. The serological study (in the indirect hemagglutination test) revealed the presence of Y. pestis capsular antigen (fraction l) in 16 out of 75 soil specimens. The transition of Y. pestis (strain EV) into the nonculturable state was experimentally shown in sterile soil extract and in association with protozoa, algae and Euglena. Bacteriologically detected Y. pestis disappeared or were represented by a few cells after day 7, while PCR could register the presence of Y. pestis at a concentration of 10(4)-10(5) microbial cells per ml until the end of the term of observation (30 days). After the enrichment of the nutrient medium with fetal serum the complete reversion of Y. pestis nonculturable forms was observed: the concentration of bacteria grown on agar was 10(5) colony-forming units per ml. Transition into the nonculturable state was also observed in distilled water. The results of this investigation are discussed with special emphasis to the possibility of the preservation of Y. pestis in the nonculturable from during the period between epidemics as applied to the problem of plague epizootic.

Animals↗
PubMedDate not supplied

[The population dynamics of Salmonella typhi and Tetrahymena pyriformis during joint cultivation].

The data on changes in the number, as well as cultural and biological properties of S. typhi and free-living T. pyriformis in the course of their joint cultivation at 2 degrees C and 25 degrees C are presented. As suggested on the basis of the results of this experiment, the interaction of S. typhi with T. pyriformis may facilitate the preservation of the bacteria in the environment and be a stage in their migration along trophic chains.

Animals↗
PubMedDate not supplied

[Dormant forms of Yersinia pseudotuberculosis during interaction with green algae and their exometabolites (population dynamics and ultrastructure)].

The dynamics of the transition of Y.pseudotuberculosis to the latent (noncultivable) state in sterile soil extraction and in soil extraction, containing Scenedesmus algae or their exometabolites, was evaluated by the bacteriological method and with the use of polymerase chain reaction. The formation of Y.pseudotuberculosis latent forms achieved its highest rate under the action of algal exometabolites (on day 11), while in the presence of algal cells such formation was delayed to 3-5 months. The partial reversion of Y.pseudotuberculosis nonculativable forms to vegetative, bacteriologically detectable forms occurred under the action of fetal serum, as well as live or killed infusoria. Transmission electron microscopy demonstrated that noncultivable Y.pseudotuberculosis had a round form, diminished cell size, denser cytoplasm and enlarged cytoplasmic space. The reversible transition of bacteria to the latent state is regarded as their adaptation to unfavorable factors during their existence in soils and water reservoirs.

Adaptation, Physiological↗