ASO

Antistreptolysin-O

Antistreptolysin-O (ASO) is an antibody produced in response to streptolysin O, an exotoxin released by group A Streptococcus bacteria. The ASO titer is used to detect a recent streptococcal infection, which is particularly helpful in diagnosing complications like rheumatic fever and post-streptococcal glomerulonephritis. Elevated ASO levels indicate a prior infection but are not specific for active infection.