Ahbrer. for antistreptolysin 0 titer. Detects the presence of antibody to the antigen streptolysin 0 produced by group Astreptococci. Streptococcal antibodies appear about 2 weeks after infection. Titer rises to a peak at 4-6 weeks and mayremain elevated for 6 months to 1 year. Test is based on the neutralization of hemolytic activity of streptolysin 0 toxin byantistreptolysin 0 antibodies in serum.

Interpretation

* Children <5 years: <85;

* 5-19 years: <170

* Adults: <85 Todd units (laboratory-specific)

Increased in: recent infection with group A-hemolytic streptococci: scarlet fever, erysipelas, streptococcalpharyngitis/tonsillitis (40-50%), rheumatic fever (80-85%), poststreptococcal glomerulonephritis. Some collagen-vasculardiseases.

Certain serum lipoproteins, bacterial growth products, or oxidized streptolysin 0 may result in inhibition of hemolysis andthus cause false-positive results.