Bloodstream antibacterial antibody positivity Antistreptolysin O antibody positivity 2024-02-20T09:54:55Z Antistreptolysin O (ASO) is an antibody against streptolysin O that is generally produced by Group A Streptococcus (GAS). GAS causes a diverse range of human infections, like pharyngitis, cellulitis, scarlet fever, and others. Moreover, a GAS infection can trigger postinfectious immune-mediated disorders, including acute poststreptococcal glomerulonephritis, acute rheumatic fever, and rheumatic heart disease. The presence of antibodies in the blood circulation that react against streptolysin O.