Antistreptolysin O (ASO), Human Plasma

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 anti-streptolysin O level begins about 1 week after infection and peaks 2-3 weeks later. In the absence of complications or reinfection, the anti-streptolysin O ASO titer will usually fall to preinfection levels within 6-12 months. Both clinical and laboratory findings should be correlated in reaching a diagnosis. Streptococcal infections are caused by bacteria known as Streptococcus. There are several disease-causing strains of streptococci (groups A, B, C, D, and G), which are identified by their behavior, chemistry, and appearance. Each group causes specific types of infections and symptoms. These antibody tests are useful for group A streptococci. Group A streptococci are the most virulent species for humans and are the cause of strep throat, tonsillitis, wound and skin infections, blood infections (septicemia), scarlet fever, pneumonia, rheumatic fever, Sydenham's chorea (formerly called St. Vitus' dance), and glomerulonephritis.