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Anti Streptolysin O Serology

Alternate test name

ASOT, Group A Streptococcal infections, Streptococcus pyogenes

Lab area
Microbiology - Serology
Method and equipment
Latex agglutination
Specimen type


Specimen requirements
  • Serum - 1 mL minimum for 1 test, >1 mL recommended for multiple tests.
Storage and transportation
  • All specimens must be shipped on dry ice
  • Exception: Specimens that will arrive at SickKids within 24 hours from the time of collection can be shipped on ice packs
Special requirements
  • Acute and convalescent sera is required for serodiagnosis.
  • The ASO titre reaches its peak by 3 - 5 weeks after infection and declines over the next 6 - 8 weeks.
  • Patients with rheumatic fever have a mean ASO titre of 500 IU/mL.
Background and clinical significance

For the diagnosis of group A streptococcal infections and their non-supprative complications

Disease condition
  • Group A streptococcal (Streptococcus pyogenes) infections
  • Non-supprative complications of group A streptococcal infection - rheumatic fever and acute post streptococcal glomerulonephritis
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