[The heterogeneity of Streptococcus pyogenes strains isolated from clinically healthy and sick children in an organized collective].

Experiments on typed strains used as an example revealed that kinetic curves obtained in the lysis by endo-N-aretylmuramidase of virulent strains greatly differed from those obtained from nonvirulent ones: the lysis rate of M+ variants was less than that of M- variants; M- strains gave rather steep kinetic curves of lysis, while those of M+ strains were more declivous. In this study group A S. pyogenes cultures isolated from healthy and sick children in a summer camp were used. The study revealed that cultures, newly isolated from healthy and sick children, were heterogeneous with respect to the M+ and M- state of group A S. pyogenes strains, the amino acid composition of pepsin fragments of M-proteins in the cultures of streptococcus M 1 under study being also heterogeneous.