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G Ia Tseneva

Publications and source records attributed to G Ia Tseneva.

At least 19 recordsLinked to original sources
PubMed1992

[The resistance plasmid of Klebsiella pneumoniae that controls its cytotoxic activity].

R-plasmid (40 MD) isolated from K. pneumoniae hospital strain makes Escherichia coli strain J62 capable of inducing a cytotoxic effect which can be detected in Hep-2 cell culture. In contrast to the initial E. coli strain J62 producing no changes in the monolayer, E. coli J62 cells containing P-plasmid induced pronounced cytotoxic changes and a sharp increase in the number of nonviable Hep-2 cells by hour 24 of interaction.

Bacterial Adhesion↗
PubMed1991

[The cultural properties and virulence of Yersinia].

Study of the cultivation properties of 82 enterobacterial strains has revealed that the colonies of virulent Y. enterocolitica (serovars O3, O9) and Y. pseudotuberculosis (serovar I) are temperature-sensitive. This sign, closely connected with the presence and expression of the virulence plasmid with a molecular weight of 44-48 MD, is not characteristic of other strains. Virulent Yersinia grown in nutrient agar for 48 hours at 37 degrees C form colonies which are smaller in diameter than those formed during cultivation at 26 degrees C (with the significance of differences t greater than or equal to 4), their diameter at 37 degrees C not exceeding 1.0 mm. The test for the determination of the temperature-sensitive morphology of Yersinia colonies, along with the tests for other virulence markers, is probably suitable for the detection of the causative agents of yersiniosis or pseudotuberculosis.

Culture Media↗
PubMed1991

[Detection of virulence markers in clinical strains of Yersinia].

The dispersion of plasmid pYV associated virulence markers in 474 Yersinia strains isolated from people has been studied. The ability to autoagglutination, calcium dependence of growth and the specific antigens were identified in 157 strains of traditionally pathogenic Yersinia enterocolitica serovars 03, 09, Yersinia pseudotuberculosis serovar I. They were not found in 223 strains of other 12 serovars of Yersinia enterocolitica, in 40 strains of Yersinia frederiksenii, Yersinia kristensenii, Yersinia intermedia. The proportion of virulent clones in the population of Yersinia is noted to depend on the conditions of its existence in vivo or in vitro. Identification of virulence markers is acknowledged to be expedient in epidemiological and ethiological estimation of the role of isolated Yersinia strains.

Antigens, Bacterial↗
PubMed1989

[Immunoelectrophoretic analysis of the antigenic composition of Yersinia].

The antigenic composition of 24. Y. pseudotuberculosis newly isolated and reference strains, 7 Y. enterocolitica strains, as well as Y. pestis vaccine strain EV, has been studied by the method of immunoelectrophoresis in agar. The antigenic composition of these bacteria has been found to be complicated and to comprise not less than 8-11 antigens, and among them nonspecific protein antigens common for enterobacteria, the common generic antigen, the antigen common with Y. pestis, as well as O-antigens specific for each serovar are identified. Immunoelectrophoretic study has shown the possibility of Y. pseudotuberculosis O-antigen, serovar I, with Salmonella sera, serogroup A, and Y. enterocolitica 09 with brucellar and cholera sera.

Animals↗
PubMed1989

[The prevalence of Yersinia and its serologic variants in patients with acute intestinal diseases of undetermined etiology in Leningrad].

Among Yersinia enterocolitica strains of 32 serovars, proposed as typing strains, some strains were found to belong to new species. Y. enterocolitica sensu stricto was represented by 21 serovars in the collection of typing strains. The occurrence of different Yersinia serovars in patients with acute enteric diseases of unknown etiology in Leningrad in 1983-1986 was determined with the use of the set of monoreceptor to 21 serovars. Out of 2,947 cultures studied by biochemical and serological methods, 81% were typed. Among them 18 Y. enterocolitica serovars were determined. Their characteristic feature was the prevalence of serovar O3 and an insignificant proportion of serovar O9. More frequently Yersinia were detected in patients with the primary diagnosis of acute enteric diseases (93.5%). The overwhelming majority (two-thirds) of Yersinia strains were isolated from children. A great number of strains detected in this study (70%) was isolated on days 10-15 of the bacteriological examination. In 927 cultures the following biovars were determined: the strains of serovar O3 belonged to biovar 4 and all other strains, to biovar 1.

Adolescent↗
PubMed1989

[The diagnostic value of determining Yersinia antigens in biological substrates of a patient].

The authors consider the time course changes in the elimination of Yersinia antigens with biological substances in various clinical presentation of yersiniosis. Altogether 101 patients aged 15-58 have been examined. It is established that Yersinia antigens are the most frequent finding in the blood irrespective of the disease form (81-90% of cases); in the gastrointestinal pattern they are more commonly identified in the faeces (63% of cases), in generalized cases the antigens occur in the urine and faeces of patients in 43 and 49% of cases, respectively. Evaluation of changes in elimination of Yersinia antigens from the body provides a good evidence for case prognosis which is of particular importance for potential cases with protracted and chronic forms of the disease as well as for evaluation of the antibacterial treatment efficacy.

Adolescent↗
PubMed1988

[Invasiveness and cytotoxicity as criteria in assessing Yersinia attenuation].

The electron microscopic study of cells HEp-2 and the complex microbiological and morphological study of tissues and organs of guinea pigs and mice infected with the isogenic pairs of Yersinia strains (Y. pseudotuberculosis I and Y. enterocolitica 09) differing in the presence of the calcium-dependence plasmid, as well as Y. pseudotuberculosis mutants resistant to rifampicin, nalidixic acid or crystal violet without this plasmid, have revealed that the invasiveness and cytotoxicity of the infective agents are not directly related to the presence of the above-mentioned plasmid in these bacteria. The use of the quantitative characteristics of virulence, such as penetration ability, intracellular multiplication, dissemination and the formation of degenerative changes, has made it possible to find out that the mutants of Y. pseudotuberculosis I, yielding the negative result in the keratoconjunctivitis test and resistant to the above-mentioned antimicrobial substances, can be arranged in the following order according to the degree of attenuation: rifr mutants--nalr mutants--kvlr mutants. In contrast to Y. pseudotuberculosis I, the loss of the calcium-dependence plasmid by Y. enterocolitica 09 is accompanied by an essential decrease in their invasive and cytotoxic properties, but this relationship is indirect and unstable. The proposed criteria intended for use in the evaluation of the degree of the manifestation of the invasive and cytotoxic properties of bacteria can be useful for the selection of optimally attenuated Yersinia strains showing promise as vaccine strains.

Animals↗
PubMed1986

[Comparative evaluation of Yersinia interaction with HEp-2 cells].

In experiments on HEp-2 cells, the comparative characterization of the mechanism of invasion and the cytotoxic action of a number of Y. pseudotuberculosis strains, serovar 1, and Y. enterocolitica strains 03 and 09 (24 strains newly isolated from human patients and rodents and 5 laboratory strains at different degrees of attenuation) has been made on the basis of data obtained by optical and electron microscopy, as well as by cytoenzymological analysis. As revealed in these experiments, the invasion of Yersinia into epithelial cells and their capacity for intracellular multiplication depend on the cytotoxicity of the bacteria, most pronounced in Y. pseudotuberculosis, serotype 1, considerably less pronounced in Y. enterocolitica 09, and poorly pronounced (or absent) in Y. enterocolitica 03. Cytopathic changes are manifested by vacuolization, the exocytosis (clasmatosis) of the peripheral cytoplasm, impoverishment in organellae, the formation of autophagosomes, the shriveling of the nuclei and the perinuclear cytoplasm, the rounding of the cells and their separation from the glass surface. The development of these changes is accompanied by the increased activity of phosphatases diffusing into the cytoplasm and by the inhibition of cell respiration and dehydrogenase activity.

Bacterial Adhesion↗
PubMed1985

[Serological variants of Yersinia enterocolitica circulating in different geographical areas of the Soviet Union].

The serological variants of a number of Y. enterocolitica strains isolated in different regions of the USSR (1,085 strains isolated from humans and animals in the North-West of the RSFSR, 76 strains isolated from humans and animals in the Krasnodar Territory and 114 strains isolated from humans only in the area east of Lake Baikal) were determined. 25 serological variants were registered in these 3 regions of the USSR. The cultures isolated from rodents belonged mostly to serovars 06,30; 03; 05; 04,33; 019,8; 016; and from humans, to serovars 03; 05; 07,8; 016; 06,30; 09.

Animals↗
PubMed1984

[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.

Animals↗