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The first Soviet kits for the serological identification of streptococci, groups A, B, and C, on the basis of the coagglutination test were developed. Each kit was intended for 35-40 determinations. The optimum concentration of streptococci during their identification by means of the reagents making up the kit was about 1.6 x 10(9) cells/ml. The specificity of the reagents in comparison with the results of the identification of streptococci by reference methods was 97.3 +/- 0.9%. The reagents making up the kits can be presumably used for solving a number of practical problems in the epidemiological surveillance of streptococcal infection.

The influence of sodium nucleinate on the growth kinetics, streptokinase activity and virulence of streptococcal populations, groups A and C, was studied. As revealed in these studies, the kinetics of the growth of the populations of both strains in the exponential phase did not depend on the concentration of sodium nucleinate in the culture medium. Measurements made on hours 15, 20 and 24 of growth showed the presence of close, direct and statistically significant correlation between the content of biomass, as well as streptokinase activity and specific streptokinase activity, and the concentration of sodium nucleinate in the culture medium. On the basis of the calculation of the coefficients of determination, the main part (70-96%) of the total dispersion of each of the above-mentioned characteristics dispersion of each of the above-mentioned characteristics could be attributed to variations in the concentration of sodium nucleinate. Five passages of faintly virulent streptococcal strains, groups A and C, were not accompanied by a rise in their virulence.

The work demonstrates the main approaches to the use of the methods of multidimensional analysis for the creation of a hypothesis on the mechanism of the epidemiological process of dysentery in organized groups. The main risk factors have been established, and their role in the formation of annual, all-the-year-round and seasonal dysentery morbidity has been quantitatively evaluated. The results of analysis show the existence of diverse variants of the alimentary route of the transmission of infection, maintaining the epidemic process of dysentery, and the necessity of differentiating measures for the prophylaxis of all-the-year-round and seasonal morbidity.

In the course of a one week observation in the organized collective body with a daily bacteriological examination for streptococcus group A carrier state 20 infections were recorded per 70 risk man-days. Statistical analysis of conditions for the recipients' infection showed bedrooms to be the main site of streptococcus infection in the organized collective bodies. The most important role in the epidemic process belonged to healthy carriers capable of infecting sensitive recipients, with the potency of microbial foci in the pharynx and the nose of about 1000-2000 microbes per standard tampon. The greatest frequency of infection occured at a distance of from 1 to 1.2 m. Consequently, the main direction of prophylaxis of streptococcus infection at the collective bodies should be associated with measures directed to the source of infection (isolation and penicillin therapy of the patients, urgent antibiotics prophylaxis in case of threatening epidemic or at its initial period).

The work is devoted to the experimental study of the effect of exogenous heterologous RNA and DNA on the outcome of infection caused by streptococci--virulent and of low virulence, of the 1st and 2nd serological types of group A, in mice. It was found that the severity of the outcomes of the infectious process was not associated with the type of nucleic acids, but was determined by the dose and the periods of their administration in relation to the time of infection of the animals and the streptococcus virulence. Aggravation of the outcomes of the infection under the effect of exogenous RNA and DNA was accompanied by an increase in the virulence of the causative agent.

The data on the application of the principles of the self regulation of the epidemic process for understanding the annual dynamics of angina morbidity in organized groups of adults are presented. In this case the reservation of group A streptococci occurs in chronic (resident) carriers, whose proportion was found to be 15.8 +/- 2.6%. The epidemic manifestations of morbidity are regulated mainly by the concentration of newly arrived members in the groups, i. e. by the size of the stratum providing the optimum conditions for the parasitization of the streptococcal population. The annual morbidity levels depend essentially not only on the heterogeneity of the group members with respect to their susceptibility to streptococcal infection, but also on the conditions of their accommodation, affecting the transmission of droplet infection. The role of individual risk factors in the variation of the quantitative characteristics of the angina morbidity manifestations under study is calculated.

This work presents the data on the complex evaluation of the population of group A streptococci, studied at each of four phases (reservation, epidemic transformation, epidemic spread, reservational transformation) of the course of the epidemic process of streptococcal infection of the respiratory tracts (tonsillitis) in an organized group of adults. The characterization of the phases of the infective agent in accordance with the level of the carrier state, the size of streptococcal foci and the virulence of streptococci is given. Thus, the study shows that the heterogeneity of group A streptococci with respect to their virulence reaches its maximum level at the phases of reservation and epidemic spread and its minimum level at the phases of epidemic and reservational transformation. The size of streptococcal foci in carriers and the virulence of streptococci isolated from them are the inter-related unidirectional signs of the population of the infective agent and, at the same time, the main factors responsible for the phase character of the epidemic process and the morbidity level in tonsillitis.

Annual dynamics of an individual infection morbidity can be divided by forms of manifestation of the epidemic process in case of admission of a relative stability for the district (collective body) under study, the level of sporadic (interseasonal, all-year-round) morbidity. Obtaining the upper border of sporadic morbidity possible under the analysed conditions permitted to assess quantitatively the activity of the factors regulating the intensity of individual forms of manifestation of the epidemic process.

Susceptibility of 64 beta-hemolytic streptococcal strains isolated from the patients with sore throat was studied by the method of serial dilutions in fluid nutrient medium (Konikov broth). Heterogenecity with respect to the sensitivity was investigated in 34 strains among separate populations of the microbes (10 to 15 in every strain). The MIC of benzylpenicillin, oxacillin and erythromycin ranged within 0.007--0.24 U/ml, 0.02--0.36 gamma/ml and 0.005--0.1 gamma/ml respectively. The MIC of benzylpenicillin with respect to separate populations most sensitive to it was 0.007--0.015 U/ml, while that with respect to the lease sensitive populations ranged from 0.015 to 0.24 U/ml. The respective values for oxacillin were 0.02--0.12 and 0.18--0.36 gamma/ml and those for erythromycin were 0.005--0.025 and 0.05--0.1 gamma/ml. Therefore, the beta-hemolytic streptococci isolated from the patients with sore throat were characterized by a rather high sensitivity to the antibiotics which was important precondition for their efficiency in treatment of the patients with the above disease.