Scarlet Fever Complications: Why Prompt Antibiotic Treatment Is Critical

Scarlet fever (group A Streptococcus pharyngitis with erythrogenic toxin) can lead to serious suppurative and non-suppurative complications if untreated.

Suppurative Complications (Direct Spread)

• Peritonsillar abscess (quinsy)
• Cervical lymphadenitis, abscess
• Otitis media, sinusitis
• Meningitis (rare)
• Bacteremia/sepsis → metastatic infections (endocarditis, osteomyelitis, septic arthritis)

Non-Suppurative (Immune-Mediated) Complications

• Acute rheumatic fever (ARF): 2–3 weeks post-infection. Jones criteria: carditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules. Can cause chronic rheumatic heart disease (mitral stenosis).
• Post-streptococcal glomerulonephritis (PSGN): 1–3 weeks post-infection. Hematuria, edema, hypertension, RBC casts. Usually self-limited but can progress to CKD.
• PANDAS/PANS: Pediatric autoimmune neuropsychiatric disorders associated with streptococcus — abrupt OCD, tics, anxiety.

Treatment

• Penicillin V (oral 10 days) or benzathine penicillin G (IM single dose) — eradicates GAS, prevents ARF if started ≤9 days after onset.
• Alternatives for penicillin allergy: macrolides, cephalosporins, clindamycin.
• Supportive: analgesics, hydration, isolation 24 hrs after antibiotic start.

Public Health

Notifiable disease. Exclude from school/work until 24 hrs on antibiotics. Contacts: test/treat if symptomatic.

Early treatment prevents complications. Rheumatic fever and PSGN are largely preventable with timely antibiotics.