A positive aso titre

1. A POSITIVE ASO TITRE ?? Dr.M.I.Beg QGH

2. WHAT IS ASO ? Group A-beta-hemolytic Streptococcus produces several virulent factors--- streptolysin o ,strptolysin s,streptokinase,Dnase B,hyaluronidase A pt infected with GABHS produces antibodies vs these virulent factors--- anti-streptolysin o(ASO), anti-sterptokinse,anti-hyaluronidase,anti-Dnase B. ASO titre takes 2 weeks to rise & remain elevated for 3-6 mo.

3. Significant aso titre? Four fold (two tube) increase in titre demonstrated over time(2-4 weeks apart) would suggest a recent steptococcal infection. Single ASO titre >200 IU in children 5-15 yrs.

4. In what clinical settings should an aso be asked for ? A pt with fever,migratory polyarthritis +- cardiac murmer---to support diag. of acute rheumatic fever . A pt with oliguria,hematuria,HTN--- post-streptococcal GN. In pts suspected to have neurological syndromes driven by a previous grp A streptococcal infection such as Pediatric auto immune neuropsychiatric disorders associated with streptococcal pyogenase( PANDAS ) & rheumatic chorea . In pts suspected to have other grp A streptococcal infections such as scarlet fever,neonatal sepsis & osteomyelitis .

5. Arthritis+raised aso=arf ? Diag. of ARF is clinical : Jone’s criteria (1 major+2 minor or 2 major criteria with supportive evidence of streptococcal infection). Elevation of ASO titre in non-ARF conditions : Post-streptococcal reactive arthritis(PSRA) Systemic onset Juvenile idiopathic arthritis SLE Takayasu d/s HSP Periodic fever syndrome

6. Aso titre –ve but strong clinical suspicion of post strep. Conditions ? What other investigation ? Anti-Dnase B In ARF : ASO +ve in 80% Anti-Dnase B +ve in 82% ASO+Anti-Dnase B +ve in 92% Streptozyme test Lacks standarization & reproducibility Not reliable Throat swab

7. Clinical diff. b/w psra & arf ? Latent period shorter (1 week) in PSRA. Arthritis is additive in PSRA rather than migratory. Relatively poor response to Aspirin in PSRA. Arthritis persists for mean period of 2 mo in PSRA. 6% of PSRA may develop mitral valve d/s . It is thus recommended that anti streptococcal prophylaxis be given for 1 yr & then discontinued if there is no evidence of cardiac involvement.

8. Thanks for your kind attention