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Biomedical subjects

A K Akatov

Publications and source records attributed to A K Akatov.

At least 19 recordsLinked to original sources
PubMed2000

[Detection of Staphylococcus aureus and Staphylococcus epidermis species specific antigens and antibodies to alpha-toxin in the blood of patients with pneumonia].

Test systems for indirect hemagglutination (IHA) test for detection of S. aureus and S. epidermidis teichoic acids and S. aureus alpha-toxin in patients' sera have been developed on the basis of immunoglobulins isolated from monospecific sera. Test system for IHA test for detection of antitoxin in donor and patients' sera has been created on the basis of highly purified alpha-toxin. Thirty donor sera and 61 sera from patients with pneumonia were analyzed. Low antibody levels in the patients may be due to the fact that the sera were collected during the first days of disease. Group of patients with high content of staphylococcal antigens and antitoxin in the blood was particularly interesting. These patients developed severe pneumonia, among whose etiological agents were S. aureus and S. epidermidis. Diagnostic analysis of patients' sera by IHA test for detection of staphylococcal antigens was more effective, accurate, and rapid in comparison with the bacteriological method; moreover, it confirmed the significance of staphylococci in the pathogenesis of pneumonia.

Antibodies, Bacterial↗
PubMed1997

[A system of step-by-step differentiation of methicillin-resistant Staphylococcus aureus].

One hundred and eighty four strains of methicillin resistant Staphylococcus aureus (MRSA) isolated in pyosurgical and burn departments of Moscow, Minsk, Omsk, Tbilisi, Vologda, Smolensk and Dushanbe were differentiated with using phages of the International Set (BIS), two collections of experimental phages and two-probe fingerprinting. More than 50 per cent of the isolates could not be typed by the BIS phages. The Experimental Collection of the N.F. Gamaleya Research Institute of Epidemiology and Microbiology (Moscow) was more useful in the differentiation in comparison to the Experimental Collection of the London Health Centre. A new approach applied by us to the establishment of our collection i.e. screening of cultures with a definite specificity of the system of the restriction-modification (by a modified phage 85) followed by their differentiation with respect to the specificity of the prophages (by the induced phages with the respective modification specificity) provided reliable and reproducible results. Our collection made it possible to classify the phage type 85 strains which as was confirmed by the fingerprinting data belonged to 3 different genotype variants. The fingerprinting had no advantages over the typing by the phages of the more extended phage set and was recommended for differentiation of the strains (14 per cent) not sensitive to the phages used. A step-by-step scheme for typing MRSA easy for use in clinical and epidemiological laboratories is described.

Bacteriophage Typing↗
PubMed1994

[Additional differentiation of methicillin resistant strains of Staphylococcus aureus typed by the international phage bank].

In the methicillin resistant strains of Staphylococcus aureus (MRSA) typed by the International Set phages the host specificity of the restriction-modification of the phage 85 DNA was determined, the finger printing of the cell DNA was carried out with using two probes and the lytic spectrum of the phages induced in them was studied. Four clones with different specificity of the restriction-modification system (rm89, rm108, rm121 and rm947) differing from that of strain PS 85 which is the host of phage 85 were detected. The strains belonging to the modification types m89, m108 and m121 contained prophages (within the respective groups) with similar lytic spectra when tested with the use of the PS strains of the International Collection and had cross antiphage immunity. Six phage variants were detected among the phages induced in the strains with the modification type m947 which could be indicative of the clone heterogeneity.

Bacteriophage Typing↗
PubMed1992

[The capacity of purified staphylococcal anatoxin to correct antigen-specific and antigen-nonspecific immunological defects].

Purified staphylococcal toxoid is capable of partially preventing the development of antigen-specific (induced by the supraoptimal dose of sheep red blood cells) and antigen-nonspecific (induced by Tahyna virus) defects of humoral immune response, as well as abolishing these defects. The presence and manifestation of the correction of virus-induced immunodeficiency is determined by the dose of the toxoid and the interval between the injections of purified staphylococcal toxoid and the infective agent.

Animals↗
PubMed1991

A new approach to establishing the set of phages for typing methicillin-resistant Staphylococcus aureus.

A new approach to using experimental phages for typing methicillin-resistant S. aureus (MRSA) non-sensitive to the phages of International Basic Set (IBS) is described. The collection Includes phage 85, modified on a culture of MRSA, and 5 phages induced from MRSA strains isolated in clinics of Moscow in 1975-76. Firstly, the modified phage selects cultures according to the specific character of its restriction-modification system, then the induced phages differentiate the selected strains into 5 groups (1, 2, 3, 4, 5) based on the specificity of the prophages they contain. Group 1 strains can further be differentiated into 5 subgroups (A, B, C, D, E) by additional phages. Forty-one MRSA strains isolated in 1987-90 in various hospitals of Moscow showing no sensitivity to IBS phages, were lysed by the modified phage, 15 of them belonging to Group 2 and isolated in the traumatological hospital, 26 belonging to Group 1 and were circulating in the burn center. Twenty-three strains of Group 1 appertain to subgroup 1B and were isolated over a 4-year period from the burned surface of patients and from the throat of a medical staff carrier.

Bacteriophage Typing↗
PubMed1991

Lysogeny of methicillin-resistant Staphylococcus aureus and the role of prophages in transfer of conjugative and non-conjugative plasmids.

The lysogenicity of 49 strains of methicillin-resistant S. aureus (MRSA) isolated in Moscow clinics in the 1970s and '80s was studied by the method of mitomycin C induction. It was found that one strain had phage of serogroup B, 33 strains had serogroup F phages and 15 strains had phages of both serogroups. In the course of genetic crossing on nitrocellulose filters it was demonstrated that serogroups B and F prophages contained in recipient cells 1) increase the frequency of transfer of conjugative plasmid pG873 and 2) mobilize transfer of non-conjugative plasmids pE994 and rms7.

Conjugation, Genetic↗
PubMed1991

[Changes in the humoral response to sheep erythrocytes based on data from a determination of the level and classes of antibodies in mice immunized with purified staphylococcal anatoxin].

The intensity and direction of the modulation of humoral immune response, induced by the action of purified staphylococcal toxoid (PST), depend on the dose of the preparation, the dose of the test antigen, the scheme of the experiment, the time of the registration of its results and the genotype of animals. PST induces the modulation of the synthesis of both IgM and IgG antibodies. The injection of small divided doses of PST enhances immune response to heterologous antigen, while a single inoculation of the total dose produces no such effect.

Animals↗
PubMed1991

[The immunomodulating action of the surface antigens of the influenza A virus in experimental staphylococcal infection].

The results of the study of influenza A virus surface antigens, hemagglutinin and neuraminidase, in the induction of nonspecific immunomodulation and protection from acute pulmonary staphylococcal infection have been studied. Protective effect, the cell composition of bronchoalveolar lavage fluid depend on the serological subtypes of surface antigens used for intranasal immunization and the infective dose of staphylococci.

Animals↗
PubMed1990

[An immunoenzyme test system for determining the staphylococcal exotoxin of toxic shock].

A highly sensitive and specific enzyme immunoassay system for the determination of staphylococcal toxic shock exotoxin (TSE), permitting the detection of TSE at a concentration of 5-10 ng/ml, has been developed. The possibility of using this assay system for the selection of TSE-producing strains has been shown. 84% of staphylococcal strains under study have been found to produce TSE.

Carrier State↗
PubMed1990

[The characteristics of the protective and antigenic activities of purified staphylococcal anatoxin in trials with mice of different genotypes].

The protective potency of purified staphylococcal toxoid by the survival rate of immunized mice challenged with the culture of Staphylococcus aureus strain L-1726 and the antigenic properties of the toxoid, determined by the level of antitoxin in the blood of mice and by the intensity of cell-mediated immunity in the spleen-cell migration inhibition test, were studied. The experiments were made on CBA and C57BL/6 mice. Purified staphylococcal toxoid was shown to possess antigenic and protective properties in a wide range of doses between 0.15 and 15 binding units per mouse. The protective effect of the toxoid in CBA mice was manifested in the presence of circulating antibodies and cell-mediated reaction or only in the presence of the toxoid. In C57BL/6 mice the protective effect of the toxoid was less pronounced and appeared in combination with the induction of cell-mediated immunity in the presence of an extremely low antibody level (0.062 I.U.).

Animals↗
PubMed1989

[A rapid method of detecting the staphylococcal exotoxin of toxic shock].

The authors suggest a simple and rapid technique, staphylococci coagglutination, for rapid detection of the toxic shock exotoxin (TSE)-producing S. aureus strains. The method is based on the sensitization of formalin-treated Cowan-1 S. aureus cells with immunoglobulins to TSE. The reagent thus obtained coagglutinates with the supernatant of TSE-producing S. aureus tested strains. This method is more sensitive than the routinely used gel immunoprecipitation. The technique for preparing the supernatant of S. aureus tested cultures is also described.

Exotoxins↗
PubMed1989

[The frequency of the production of toxic-shock exotoxin by Staphylococcus aureus strains isolated in the USSR].

515 S. aureus strains, isolated from carriers and patients with staphylococcal infection in different regions of the USSR, were studied. Of these, 52.2% were found capable of producing exotoxin of toxic shock (ETS). The occurrence of the capacity for ETS production was the same among the strains isolated from the upper respiratory ways of carriers and from the purulent inflammatory foci of patients and little varied in staphylococci isolated in different regions. The study revealed that in strains sensitive to the typing phages of the International Set the capacity for ETS production occurred considerably more frequently than in nontyped cultures. No essential differences with respect to this sign between strains belonging to different phage groups were established.

Adult↗
PubMed1989

[Patterns in the antigen-nonspecific modulation of the B-cell activity in mice under the influence of a purified staphylococcal anatoxin].

Purified staphylococcal toxoid (PST) has been shown to be an antigen-nonspecific immunomodulator, capable of inducing changes in the immune response of B-cells to unrelated antigens, such as sheep red blood cells (SRBC), in a wide range of doses (from 15 to 0.15 binding units per mouse). The manifestation of the immunomodulating effect depends on the conditions of the experiment: the doses of PST and SRBC, the age of mice, the sequence of the injections of the antigens and the intervals between the injections. The simultaneous injection of PST and SRBC induces, as a rule, an increase in immune response to the test antigen, while their separate injection induces mainly immunosuppression.

Adjuvants, Immunologic↗
PubMed1989

[Production of toxic shock exotoxin by Staphylococcus aureus strains resistant and sensitive to antibiotics].

Three hundred and ninety two strains of S. aureus isolated from bacteria carriers and patients with staphylococcal infections in different regions of the Soviet Union were investigated. 55.9 per cent of the isolates were able to produce exotoxin of toxic shock. No regular relation between resistance to definite antibiotics (tetracycline, chloramphenicol, benzylpenicillin, streptomycin, lincomycin, erythromycin, oleandomycin, gentamicin and methicillin) and the polyresistance range on the one hand and the ability to produce toxic shock exotoxin on the other hand was revealed.

Anti-Bacterial Agents↗
PubMed1989

[The role of cellular and humoral factors of body resistance in the development of experimental influenza-staphylococcal infections in mice].

The clinico-experimental studies of mixed influenza-staphylococcal infection constantly point to the development of the aggravation of the infectious process due to the synergic action of the bacterial and viral infective agents. But, as shown by the authors of the present work, in those cases when the experimental infection with the virus was preceded by staphylococcal infection by 72 hours no synergism was observed. In cases of infection with adaptogenic virus the mortality rate of mice resulting from meningococcal infection was twice as low. The possible explanation of this fact is discussed.

Animals↗
PubMed1988

[Experimental phages for differentiating nontypable methicillin-resistant Staphylococcus aureus].

The possibility of using phages, isolated from the lysogenic cultures of methicillin-resistant staphylococci and modified in methicillin-resistant cultures of phage 85, for the differentiation of nontypable staphylococcal strains has been studied. The variants of phage 85 cannot be used for the determination of differences between the strains of methicillin-resistant cultures; they are not suited for typing. For this purpose the collection of phages isolated from lysogenic methicillin-resistant cultures should be used.

Bacteriophage Typing↗