[Experience in studying protein A in staphylococcal cultures].

Methods of quantitative and qualitative determination of protein A in staphylococcus cultures were studied comparatively. The maximal number of strains positive by protein A were revealed by means of indirect hemagglutination test with cell extracts. Quantitative and qualitative characteristics by protein A can be used in studying the problems of strain and clone heterogeneity of S. aureus. A common antigen was revealed in the reactions with human gamma-globulin in 21 of 38 S. aureus strains, and in 1 of 11 S. epidermidis strains; the presence of this antigen failed to correlate with the quantitative protein A content in the same strains.