Clinical meaning
Pharyngitis is inflammation of the pharynx, with viral etiologies (rhinovirus, adenovirus, EBV, influenza) accounting for 70-85% of cases and Group A Streptococcus (GAS/S. pyogenes) accounting for 15-30% in children and 5-15% in adults. GAS pharyngitis is significant because untreated infection can trigger post-infectious immunologic complications: acute rheumatic fever (ARF — molecular mimicry between streptococcal M protein and cardiac tissue causing valvulitis) and post-streptococcal glomerulonephritis (PSGN — immune complex deposition in glomeruli). The Centor criteria (modified McIsaac) guide the need for testing: fever > 38°C, tonsillar exudates, tender anterior cervical lymphadenopathy, absence of cough, and age adjustment. A score ≥ 3 warrants rapid antigen detection test (RADT) or throat culture. Antibiotics treat GAS to prevent ARF (antibiotics must be started within 9 days of symptom onset), reduce symptom duration by 1-2 days, and decrease transmission.
Diagnosis & workup
Diagnostics & workup: - Apply modified Centor (McIsaac) criteria: fever >38°C (+1), tonsillar exudates (+1), tender anterior cervical LAD (+1), absence of cough (+1), age 3-14 (+1), age 15-44 (0), age ≥45 (-1) - Score ≥ 3: perform RADT (rapid antigen detection test) - Negative RADT in children/adolescents: confirm with throat culture (RADT sensitivity 70-90%) - Negative RADT in adults: throat culture optional (lower rheumatic fever risk) - Score ≤ 2: neither testing nor antibiotics recommended (viral pharyngitis likely) - Monospot (heterophile antibody test) if EBV mononucleosis suspected (exudative pharyngitis + fatigue + splenomegaly + atypical lymphocytes)