[The M-protein heterogeneity of Streptococcus pyogenes strains isolated from clinically healthy and ill children in an organized collective].

The study of the kinetic curves of the lysis of group A S. pyogenes cell-walls (cells), serovars 29 and 12 M, variants M+ and M-; with endo-N-acetyl-muramidase revealed that the kinetics of the lysis of virulent and avirulent strains was different: variant M- was lyzed faster than M+. This difference in the cell-wall lysis of both variants made it possible to use this method for the identification of M+ and M- states of the strains. 18 group A S. pyogenes cultures were studied. The cultures isolated from healthy and sick children in an organized group belonged to variants both M+ and M-. The pepsin fragments of M-proteins of group A S. pyogenes, type M 1, isolated in dynamics from a carrier and a patient, were studied. Their amino acid compositions were studied, and differences between them were established. The data thus obtained indicate that heterogeneity is characteristic of both the surface structure of streptococci and the individual components of their surface, in particular, M-protein.