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Previous reports from this laboratory (1, 2) have presented preliminary data, suggesting that there are antigenic and enzyme system changes in beta hemolytic streptococci resistant to penicillin and streptomycin. These data were all qualitative and were unconfirmed by quantitative methods. The present study is a continuation of this work. The same strains of group A and C streptococci were made resistant separately to bacitracin and aureomycin. Representative members of each group, resistant to all four antibiotics, were studied for alterations in: 1) streptolysin S; 2) streptokinase; 3) proteinase; 4) ribonuclease activity. That such variations might be expected was first suggested by the observation that reversible changes in the hemolytic behavior of streptococci from beta to alpha or gamma type of hemolysis occurred when the organisms were growing on maximal concentrations of either penicillin or streptomycin.

ANTIGENIC AND ENZYME SYSTEM CHANGES IN BETA HEMOLYTIC STREPTOCOCCI RESISTANT TO PENICILLIN, STREPTOMYCIN, BACITRACIN AND AUREOMYCIN 1234