Poststreptokokkale

Poststreptokokkale refers to disorders that occur after an infection with group A Streptococcus (Streptococcus pyogenes). The term is used for sequelae that arise weeks after a streptococcal throat infection or skin infection, most commonly rheumatic fever and poststreptococcal glomerulonephritis (APSGN). The conditions reflect immune-driven processes rather than ongoing infection.

Pathogenesis is mainly immune-mediated. In rheumatic fever, antibodies generated against streptococcal antigens cross-react with host tissues (molecular mimicry), particularly in the heart and joints. In APSGN, immune complex deposition and complement activation in the kidneys drive inflammation. The latency period after the initial infection can vary from a few weeks to several weeks.

Clinical features vary by syndrome. Rheumatic fever presents with fever, migratory polyarthritis, carditis (which can affect heart valves), chorea, subcutaneous nodules, and erythema marginatum. APSGN typically causes edema, hypertension, hematuria, proteinuria, and reduced urine output. Both conditions warrant evaluation of a recent streptococcal infection, validated by positive culture, rapid antigen test, or elevated streptococcal antibody titers (e.g., ASO, anti-DNase B).

Diagnosis relies on established criteria and laboratory findings. Rheumatic fever uses Jones criteria and evidence of prior GAS infection. APSGN is suggested by low complement levels (especially C3), elevated streptococcal antibodies, and characteristic urinary findings.

Treatment includes eradication or treatment of residual infection when present, and management of immune-related symptoms. Antibiotics (typically penicillin) are used to address any active streptococcal infection and to prevent recurrence in rheumatic fever. Anti-inflammatory therapy (NSAIDs or aspirin) is common; corticosteroids may be used for severe carditis. Rheumatic fever often requires long-term antibiotic prophylaxis to prevent relapse. APSGN is typically managed supportively, with blood pressure and fluid balance control; most cases resolve, though some patients may have lasting kidney effects. Prevention emphasizes prompt treatment of streptococcal infections.