The streptolysins of various groups and types of haemolytic streptococci; a serological investigation

Abstract

1. Group A haemolytic streptococci produce two distinct varieties of streptolysin:(a) Streptolysin O which is oxygen sensitive.(b) Streptolysin S which is serum extractable.These two streptolysins are neutralized by separate antibodies which appear to be entirely unrelated.2. Neutralization experiments in vitro with group A antistreptolysin O show that streptolysin O is formed by strains belonging to groups A, C (human) and G; it is not formed by strains belonging to groups B, C (animal), D, E, H and K. The relation of group F strains to streptolysin O is at present uncertain.3. Group A strains of different serological types all produce streptolysin S neutralizable by group A antistreptolysin S. Strains belonging to groups B, C, D, E, F, G, H and K do not produce streptolysin S neutralizable by group A antistreptolysin S. The neutralization is therefore group-specific but not type-specific.