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An enzyme immunoassay (EIA) system for detection of staphylococcal enterotoxin, type C, has been developed. The sensitivity of the system is 1 ng/ml. The optimum EIA parameters have been worked out. The absence of false positive results with heterologous toxins confirms the specificity of the assay system. The possibility of the detection of staphylococcal enterotoxin, type C, in staphylococci isolated from different sources has been shown.

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The action of immunomodulators, purified staphylococcal toxoid (PST) and lycopid, on secondary immunodeficiency state developing during infection caused by Coxsackie virus B3 was studied. This defect was manifested by delayed hypersensitivity to sheep red blood cells (SRBC) and the suppression of neutralizing antibodies to poliomyelitis virus. Depending on the scheme of the experiment, PST normalized the defects of immune response to SRBC or poliovirus, increased suppression or showed no activity. Lycopid corrected the defects of humoral response to SRBC. The combination of PST and lycopid was found to produce no increase of suppression. The suggestion was made on the expediency of combination of two (and probably more) immunomodulators for increasing the efficiency of correction of secondary immunodeficiency.

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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.

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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.

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Highly purified teichoic acids (TA) were isolated from Staphylococcus aureus and S. epidermidis and characterized. The preparations of TA were highly species-specific. For the first time monospecific sera to S. aureus and S. epidermidis were obtained. From these monospecific sera immunoglobulins were isolated and used for the preparation of reagents for the passive hemagglutination (PHA) test and the enzyme immunoassay (EIA). The sensitivity of the PHA test and EIA was 15 micrograms/ml when S. aureus and S. epidermidis were used and 10(6)-10(7) cells/ml when whole microbial cells were used. The diagnostic preparations proved to be highly specific and did not react with other preparations isolated from S. aureus and S. epidermidis, as well as from bacteria belonging to other taxa. Experiments on rabbits, carried out with the use of newly developed test systems, demonstrated that staphylococci could be detected in the blood as early as 10 minutes after the intravenous infection of the animals and until day 12.

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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.

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Purified staphylococcal toxoid (PST) was shown to be capable of preventing the development of secondary antigen-nonspecific immune deficiency in mice, immunized with whole-cell pertussis vaccine. The immunocorrective action of PST was manifested after its injection before (on day -1), simultaneously with and after (on day +1) the injection of whole-cell pertussis vaccine. Correction was either complete or partial, depending on the scheme of the experiment and the dose of PST.

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Purified staphylococcal toxoid modulates (mainly suppresses) cell-mediated immune response to heterogeneous antigens of animal origin (to sheep red blood cells as shown by the delayed hypersensitivity reaction) or bacterial origin (to BCG as shown by the splenocyte migration test). The direction and manifestation of modulation depend on the strain of mice, dose of the toxoid, dose and nature of the test antigen and the immunization schedule (intervals between the injections of the antigen).

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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.

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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.

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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.

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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.

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"Sandwich" variant of ELISA was used to identify staphylococcal enterotoxins (SE), types A and B, in S. aureus filtrates inducing food poisoning, in extracts of the lactic acid product for infants "Biphilin" that caused staphylococcal infection, and in foods contaminated with SE in varying concentrations. It has been shown that ELISA used for SE identification in foods permits revealing SE, types A and B, in liquid products in concentrations of 1-2 ng/ml (that is 1000-fold more sensitive, than the immunodiffusion test, 400-800-fold more sensitive than the passive hemagglutination test, and 10-fold more sensitive than the indirect passive hemagglutination test), and in solid products--in concentrations of 5-10 ng/g (after artificial contamination).

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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.

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