What is the recommended treatment for scarlet fever?

Treatment of Scarlet Fever

Penicillin V (phenoxymethylpenicillin) is the recommended first-line treatment for scarlet fever, administered at a dose of 250-500 mg every 6-8 hours for 10 days. 1

Diagnosis and Clinical Features

Scarlet fever is an infectious disease caused by group A streptococcal bacteria (Streptococcus pyogenes) that produces pyrogenic exotoxins. It typically presents with:

• Fever ≥38°C (102°F) persisting for at least 5 days 2
• Distinctive sandpaper-like, papular skin rash 3, 4
• Sore throat 5, 4
• Changes in the oral cavity including "strawberry tongue" and erythema of the oropharyngeal mucosae 2
• Bilateral bulbar conjunctival injection without exudate 2
• Changes in extremities including erythema of palms and soles 2
• Cervical lymphadenopathy, usually unilateral 2

Treatment Recommendations

First-line Treatment

• Oral Penicillin V (phenoxymethylpenicillin): 250-500 mg (400,000-800,000 units) every 6-8 hours for 10 days 2, 1
  • It is crucial to complete the full 10-day course to prevent complications such as acute rheumatic fever 1, 2

Alternative Treatments for Penicillin-Allergic Patients

• First-generation cephalosporins: For patients without immediate hypersensitivity to β-lactam antibiotics 2
• Macrolides: For patients with true penicillin allergy 2
• Amoxicillin: 500 mg every 12 hours or 250 mg every 8 hours for adults; for children, 25 mg/kg/day in divided doses every 12 hours or 20 mg/kg/day in divided doses every 8 hours 6

Rationale for Antibiotic Treatment

Antibiotic therapy for scarlet fever is recommended regardless of disease severity to:

1. Speed recovery 7
2. Reduce the length of time the infection is contagious 7
3. Reduce the risk of complications 7, 8

Complications if Untreated

Early antibiotic treatment is essential to prevent both local and systemic complications, which may include:

• Acute rheumatic fever 5, 4
• Glomerulonephritis 3, 4
• Bacteremia 3
• Pneumonia 3
• Endocarditis 3, 4
• Meningitis 3

Management of Close Contacts

• Routine throat cultures or treatment for asymptomatic household contacts is generally not necessary 2
• In outbreak situations (schools, daycare centers, institutions):
  • Perform throat cultures for all patients 2
  • Treat only those with positive throat cultures 2
  • Intramuscular benzathine penicillin G has been effective in terminating outbreaks 2

Important Clinical Considerations

• Begin antibiotic treatment immediately upon clinical diagnosis to reduce risk of complications and spread of infection 5
• Patients should be considered contagious until 24 hours after starting antibiotic therapy 7
• Monitor for clinical improvement within 48-72 hours of starting antibiotics 2
• If symptoms persist beyond 3-5 days of antibiotic therapy, reassess the diagnosis and consider alternative pathogens 2
• Antipyretics may be used for symptomatic relief of fever but do not replace the need for antibiotics 2

Follow-up

• Clinical follow-up is recommended to ensure resolution of symptoms 2
• Post-treatment throat cultures are not routinely recommended unless symptoms persist or recur 2
• Patients should be advised to complete the full course of antibiotics even if symptoms resolve quickly 1, 2