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Antistreptolysin (ASO)

Group A streptococci cause different infections: skin diseases or angina tonsillaris that may be followed by glomerulonephritis, acute endocarditis, Sydenham’s Chorea, and acute rheumatic fever, when the upper respiratory tract is infected. These infections can later lead to damage of the heart or the kidneys. Early diagnosis, efficient treatment and monitoring of the patient can reduce these risks. Several metabolites of β‑hemolyzing streptococci are exogenous toxins for the human body, e.g. NAD‑glycohydrolase, streptodornases (ADNases), and hyaluronidase which induce immunological defense reactions. The most clinically important antibody reactions are found against streptolysin O, streptococcaldeoxyribonuclease and streptococcal-hyaluronidase. Immunological testing for specific antibodies provides useful information about the degree of the streptococcal infection and the course of disease. The determination of the level of antistreptolysin O antibodies (ASO) is the most widely used. Eighty-five percent of patients with acute rheumatic fever show increased ASO levels. ASO levels should be monitored several times at weekly intervals to obtain useful data. The titre development can indicate either a successful antibiotic treatment or the persisting antigen stimulus even if the clinical signs of the infection have already disappeared.

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