Also known as: ASO

Streptolysin is a hemolysin produced by group A streptococci. In an infected individual streptolysin O acts as a protein antigen, and the patient mounts an antibody response. A rise in antibody level begins about one week after infection and peaks two to three weeks later. In the absence of complications or reinfection, the ASO titer will usually fall to preinfection levels within 6 to 12 months. Both clinical and laboratory findings should be correlated in reaching a diagnosis.