Biomedical subjects

Iu V Reztsova

Publications and source records attributed to Iu V Reztsova.

10 recordsLinked to original sources

PubMed1992

[The virulence of Streptococcus pneumoniae strains--the causative agents of pneumococcal infection at different sites].

A total of 256 S. pneumoniae strains, the causative agents of infectious processes with different localization, were studied for their virulence (in experiments on mice), neuraminidase and aldolase-protease activity (APA). In pneumococcal strains isolated 18-20 hours after intraperitoneal infection their virulence for mice increased, on the average, 1,000-fold and the average level of extracellular and cellular neuraminidase and APA increased 2- to 5-fold in comparison with the initial values. Pneumococcal strains causing acute pneumococcal infections with different localization, or the aggravation of such infections, exhibited higher virulence for mice and higher levels of neuraminidase and APA, while the inflammatory process at the period of clinical remissions was mainly maintained by S. pneumoniae cultures with low virulence.

Animals↗

PubMed1991

[A comparison of their virulence for mice and the enzymatic activity of Streptococcus pneumoniae strains].

In most cases no correlation between the virulence of S. pneumoniae and their enzymatic activity was registered in 101 S. pneumoniae strains isolated in pneumococcal infections of different localization. Pneumococcal strains belonging to different serotypes and characterized by their low virulence for mice (LD50 = 10(6) colony-forming units) had the highest neuraminidase and protease-alzolase activity in comparison with highly virulent cultures of these bacteria. In pneumococcal cultures in the R-form avirulence for mice occurred mainly in combination with low enzymatic activity.

Animals↗

PubMed1988

[Virulence of Streptococcus pneumoniae strains belonging to different serovars].

The study of the virulence of 352 S. pneumoniae strains isolated from patients with inflammatory lung diseases revealed that their virulence depended, to a certain extent, on the state of the polysaccharide capsule of streptococci, as among 299 typed cultures 38.1% were virulent, while out of 53 nontypable strains of these bacteria only 8 strains (15.1%) proved to be highly pathogenic for white mice and all S. pneumoniae R-forms proved to be avirulent. All 11 S. pneumoniae strains under study belonging to serovars 1 and 2 and 87% of the cultures belonging to serovar 3, isolated from patients with inflammatory lung diseases in Leningrad, were highly virulent. The characteristic feature of S. pneumoniae cultures of other serotypes was their wide spectrum of pathogenicity. S. pneumoniae cultures isolated from the spinal fluid of patients with pneumococcal meningitis also differed in their pathogenicity levels but strains highly pathogenic for mice prevailed.

Animals↗

PubMed1988

[Epidemiologic problems of pneumococcal infection].

During the microbiological examination of 314 tentatively healthy donors, residents of Leningrad, Streptococcus pneumoniae was detected in the rhinopharynx of 94 donors (29.9%) in amounts ranging from a few individual microbial cells to 10(6) microbial cells with the mean geometric concentration equal to 3.58 lg. Antipneumococcal antibodies were detected in the blood of 147 donors (46.8%). The occurrence of antipneumococcal antibodies was approximately 2.5 times higher than the average level of carriership, but in most cases the dynamics of immunological reactions changed in the same direction. Considerable monthly and annual fluctuations in the occurrence of pneumococcal carriership and antipneumococcal antibodies, as well as their correlation with the epidemic rises of acute respiratory diseases, influenza and other acute respiratory viral diseases, were established. These data indicate that pneumococcal infection plays a definite role in the epidemic rises of acute respiratory diseases.

Antibodies, Bacterial↗

PubMed1986

[Antigenic structure of the polysaccharide capsule of Streptococcus pneumoniae strains isolated in Leningrad 1978-1984].

The serotyping of 826 S. pneumoniae strains, isolated in conditionally diagnostic concentrations from the bronchial contents of patients with acute and chronic inflammatory pulmonary diseases during 1978-1984 in Leningrad, was made. The study revealed the prevalence of serotypes and groups 6, 23, 9, 3, 19, 15 and the undulant character of fluctuations in their annual occurrence. The specific proportion of the prevailing serotypes of S. pneumoniae among the cultures isolated from patients with acute pneumonia and acute bronchitis (6 and 19) was found to differ from that among S. pneumoniae strains isolated from patients with chronic bronchitis; in the latter patients serotypes 3 and 9 occurred more frequently (P less than 0.01).

Adult↗

PubMed1986

[Etiology of acute pneumonia occurring against a background of influenza and other acute respiratory viral infections].

The etiology of acute pneumonia (AP) was studied in 229 patients who had the disease simultaneously with influenza (106 patients), other viral and mycoplasmal infections (48 patients), and without concomitant acute viral infections (75 patients). The use of the quantitative microbiological method and the indirect immunofluorescence test with autostrains or Streptococcus pneumoniae strains of serotypes 2, 3, and 6, prevailing in Leningrad in patients with acute inflammatory diseases of the lungs, made it possible to find out the pneumococcal etiology of AP in 95% of patients irrespective of the presence of acute respiratory viral infections. The etiological role of opportunistic bacteria was revealed in 13 AP patients (5.7%); in 2 of them the causative agent of AP was Staphylococcus aureus and in 11, various species of Gram-negative enterobacteria. The latter were the cause of complications in 8 cases of pneumococcal pneumonia.

Acute Disease↗

PubMed1984

[Antibiotic sensitivity of Streptococcus pneumoniae strains isolated from the bronchial contents of patients with inflammatory lung diseases].

The study of the sensitivity of 2681 pneumococcal strains to antibiotics, carried out in 1976-1982, demonstrated that most of these strains circulating in Leningrad were sensitive to penicillin, levomycetin, erythromycin and oleandomycin. Penicillin-resistant pneumococcal strains were found to appear in 1980 and later showed a definite increase in number, reaching 4.4% of all strains in 1982. Simultaneously the appearance of levomycetin- and erythromycin-resistant strains and the increase of their relative significance were established. Most of the pneumococcal strains isolated in Leningrad were not sensitive to monomycin, streptomycin and tetracyclin.

Anti-Bacterial Agents↗

PubMed1984

[Problems in dissociating strains of Streptococcus pneumoniae].

The processes of dissociation occurring under the influence of soluble starch and some substances with surface activity (Tween-80, cattle bile and sodium desoxycholate) in 4 pneumococcal strains (Nos. 204, 205, 1225, 1317) isolated from patients with acute and chronic inflammatory lung diseases have been studied in vitro. Stable pneumococcal R-forms have been obtained by treatment with 0.1% sodium desoxycholate and 0. 5% bile and subsequent selection. The colonies of pneumococcal R-forms are characterized by a large size, a rough surface, uneven edges and pronounced alpha-hemolysis. The features typical of the population of these cultures are the polymorphism of cell element, the formation of long diplococcal chains, the almost complete disappearance of the capsule, as well as the negative results of the slide agglutination test and Neufeld s test with "omni" and typing pneumococcal antisera. Besides, the pneumococcal R-forms thus obtained have proved to be resistant to optochine (6 micrograms/ml) and bile (10-20%) and to possess low virulence.

Bronchi↗

PubMedDate not supplied

[Streptococcus pneumoniae adhesion to mouse tracheal explants and its inhibition by carbohydrate preparations].

The method for the cultivation of tracheal explants of non-inbred mice was developed. The adhesive capacity of 34 S. pneumoniae strains belonging to 15 serotypes was studied. The geometric mean of S. pneumoniae concentrations attached to the organ culture was 8.93 x 10(4) CFU/ml. D-galactose blocked adhesion, on the average, 4.35 x 10(4) (95.5%) CFU/ml. The level of S. pneumoniae adhesion and the degree of its inhibition were dose- and strain-dependent. The use of different variants of the combination of D-galactose and S. pneumoniae made it possible to come to the conclusion that this monosaccharide blocked the receptors of epithelial cells and bacterial adhesins.

Acetylglucosamine↗

PubMedDate not supplied

[A method for preventing experimental pneumococcal infection].

Lethal pneumococcal infection in mice, infected intranasally, can be induced only by highly virulent strains of pneumococci. The introduction of N-acetylglucosamine and/or D-galactose, both 1 hour before the introduction of pneumococci or simultaneously with their introduction, prevented the development of this infection in 83-91% of mice used in the experiment. The use of the mixture of these carbohydrates did not change the level of their activity. These carbohydrates were shown to be capable of protecting mice from the intranasal introduction of 100-1000 LD50 of Streptococcus pneumoniae highly virulent strains, adapted to the respiratory tracts and lungs of mice.

Acetylglucosamine↗