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Detection rate of enterotoxigenic Staphylococcus aureus isolated from faeces of 62 children aged from 3 months old to 7 years old with intestinal dysbacteriosis was studied by indirect hemagglutination assay and enzume immunoassay. It was shown that strains of S.aureus producing staphylococcal enterotoxin A (SEA) are prevailed (40.3%) in children with disturbances of intestinal microflora while staphylococcal enterotoxin B (SEB)-producing strains were detected in 20.9% of children. Amount of produced enterotoxin varied for SEA from 125 ng/ml to 2000 ng/ml and for SEB--from 125 ng/ml to 250 ng/ml. Inverse dependence of detection rate of enterotoxin-producing strains in faeces on age of children was established. The most number of enterotoxigenic strains of S.aureus was detected in infants. These data point to expediency of determination of enterotoxin-producing ability of S. aureus strains isolated from children with dysbacteriosis as measure of danger of this microorganism for children's health and indication for adequate actions for its elimination.

The content of methicillin resistant S. aureus (MRSA) genes, coding the synthesis of staphylococcal enterotoxins A, B, C (sea, seb, sec) and the toxin of the toxic shock syndrome (tst-H) which was classified with pyrogenic toxins of superantigens (PTSAgs), was studied with the use of PCR amplification. The study revealed the specific features of the content of genes sea and sec, detected in epidemic strains, identified earlier and found to circulate in Russian hospitals. Among the isolates, genetically related to international epidemic strain EMRSA-1, isolates containing no gene sea were detected, while among the isolates genetically related to strain EMRSA-2, isolates containing not only gene sea, but also gene sec were detected, which was indicative of the tendence of this epidemic strain in the direction of further acquisition of pathogenicity genes. As revealed in further studies, among the cultures obtained in bacteriemia, 88% contained gene sea. Two out of three isolates obtained from patients with the symptoms of toxic shock also contained this gene. The differences in the content of genes PTSAgs (sea, seb, sec and tst-H) could serve as a genetic criterium for the differention of isolates circulating in a hospital, as well as for a more complete characterization of the epidemic strains MRSA. The determination of the given genetic markers in genetic strains in circulating strains will make it possible to prognosticate the structure, severity and outcomes of hospital infections. The conditions of PCR amplification for the determination of genes sea, seb, sec and tst-H, as well as multiplex PCR for the determination of genes sea and seb, were developed.

The occurrence of Staphylococcus aureus strains producing enterotoxins of types SEA and SEB, which isolated from patients of different profile and caused the infectious process accompanied by pronounced intoxication without vomiting and enteric disturbances, was determined by means of the indirect hemagglutination test. The collection included 28 strains isolated in sepsis, 38 strains isolated in pneumonia, 57 strains isolated from patients with burns and 23, from the hands and nasopharynx of the medical staff. Among the staphylococcal strains isolated in sepsis, 75.6% synthesized SEA and 5.4%, SEB. The occurrence of SEA- and SEB-positive strains isolated in pneumonia was, respectively, 42.1% and 2.6%. From patients with burns SEA-positive staphylococci were mainly isolated (92.9%). Only 3% of the cultures isolated in wound infections produced SEA. From the medical staff, 13.4% of SEA-positive strains and 17.3% of SEB-positive strains were isolated. The data obtained from this study indicate the expediency of the determination of the enterotoxigenic properties of S. aureus clinical isolates in medical institutions for prophylactic measures with a view to the prevention of the spread of pathogenic clones.

The study of the length of the amplification products of the coagulase gene with the subsequent restriction analysis (the method of PCR--restrictive fragment length polymorphism, or RFLP) was used for typing 90 S. aureus strains. Among the strains under study, 78 were methicillin-resistant S. aureus (MRSA) strains, including 74 obtained in 1986 - 2002 in hospitals of different cities of the Russia and Belarus, as well as epidemic strains EMRSA-1, -2, -3, -12, obtained from the National Laboratory of Health, London (UK). The use of this method made it possible to type all the strains under study, which were differentiated into 9 groups by means of endonuclease Sfo1 and 7 groups by means of Alu1. Majority of clinical MRSA strains, belonged, according to the type of restriction, to groups 4 and 5. The study of the coagulase gene by the method of PCR - RFLP made it possible: to analyze the epidemic situation in hospitals for a period of several years; to compare the properties of strains isolated in different hospitals; to establish the genetic relationship of strains, isolated in 1998 - 2002, with strains, isolated in 1986 - 1990. The results of the study suggest that at least two epidemic MRSA strains, genetically similar to international strains, circulate in hospitals of Russia.

The data on a high level of interleukin production in mice, resistant to staphylococcal infection (CBA), in comparison with that in mice, sensitive to this infection (C3HA), are presented. The production of interleukin 1 in intact and infected mice of different strains exhibited no differences between these strains, but its level considerably increased after the inoculation of the animals. A the same time differences in the synthesis of IgM and IgG1 in intact and infected mice of different strains were noted.

The difference between the proliferative response of spleen cells to S. aureus cytoplasmic antigen on days 5 and 9 of the infectious process was shown in experiments of CBA and C3HA mice, opposite in their susceptibility to systemic staphylococcal infection. Hybrid mice F1 (CBA x C3HA) inherited a high level of proliferative response on day 5 (as in resistant CBA mice) and its low level on day 9 (as in susceptible C3HA mice). These data on genetic differences in proliferative response to S. aureus cytoplasmic antigen were confirmed in the test of the proliferation of lymph node lymphocytes taken from mice of these lines immunized with the above-mentioned antigen in Freund incomplete adjuvant into the pad of their paws 14 days before the test.

It was shown in experiments on a model of fatal staphylococcal sepsis in 200 mice and 15 dogs that the perfusate of a pig's spleen obtained by perfusion of the isolated organ with a dextran solution (rheopolyglucin, polyglucin) is capable of preventing the animals' death. Intravenous infusion of 400-500 ml of a xenospleen perfusate at an interval of 1-3 days, which was included in the complex of postoperative treatment of 45 patients with destructive diseases of the abdominal organs complicated by peritonitis and sepsis, contributed to reduction of lethality and the terms of recovery. It is shown that the main effect, besides detoxification, is based on immunomodulation at the cost of biologically active substances produced by the cells of a xenospleen and contained in the perfusate. The best results were produced with the use of the perfusate of a xenospleen in the early periods after radical operation and thorough cleansing of the source of the infection.

Experiments were conducted on 1500 albino mice; protective activity of 7 batches of S. aureus capsular antigen isolated from 5 strains was studied. The animals were immunized subcutaneously with different doses of the preparation (from 0.001 to 10000 microgram) once, twice, and thrice, and infected intraperitoneally with 6 encapsulated cultures. Capsular antigen proved to possess weak protective properties. The following regularities were revealed: 1) high antigen doses (over 5 microgram) increased mouse sensitivity to staphylococcus infection; 2) the greatest protective activity was shown by doses within 0.01-1 microgram; 3) there was no distinct "dose-effect" dependence; 4) single immunization was less effective than double and triple; 5) antigenic specificity of the capsular material was not connected with its protective properties.

The authors elaborated suitable conditions for cultivation of freshly isolated Staph. aureus, which offered a possibility of detection among them of a high percentage (75.2) of capsular cultures. It was shown that when grown in serum semifluid agar capsular staphylococci formed diffuse colonies of three different types. No correlation between the presence of the capsule, on the one hand, and the absence of the flocculus-forming factor and resistance to the type bacteriophage, on the other hand, was revealed in the Staph. aureus strains.