What is the treatment for an 8-year-old male with a sandpaper rash on the face and arms, suggestive of a group A beta-hemolytic streptococcal (GABHS) infection?

Treatment of Sandpaper Rash (Scarlet Fever) in an 8-Year-Old Male

Treat this child immediately with oral amoxicillin 50 mg/kg once daily (maximum 1000 mg) for a full 10 days, as this sandpaper rash represents scarlet fever from Group A Streptococcus (GAS) pharyngitis. 1, 2, 3

Why Amoxicillin is the Treatment of Choice

• Penicillin and amoxicillin are the first-line treatments for GAS infections (including scarlet fever) due to proven efficacy, narrow spectrum, safety, and low cost. 1, 2
• Group A Streptococcus has never developed resistance to penicillin anywhere in the world, making it the gold standard treatment. 1, 2
• Amoxicillin is preferred over penicillin V in children due to better taste acceptance of the suspension and improved adherence with once-daily dosing. 2
• The FDA approves amoxicillin for treatment of infections due to susceptible Streptococcus species (α- and β-hemolytic isolates). 3

Critical Treatment Requirements

• A full 10-day course is absolutely essential to achieve maximal pharyngeal eradication and prevent acute rheumatic fever. 1, 2, 3
• Treatment should be continued for at least 10 days for any infection caused by Streptococcus pyogenes to prevent the occurrence of acute rheumatic fever. 3
• Shortening the course by even a few days results in appreciable increases in treatment failure rates and rheumatic fever risk. 1

Understanding Scarlet Fever

• The "sandpaper rash" is pathognomonic for scarlet fever, which is GAS pharyngitis with a characteristic erythrogenic toxin-mediated rash. 4, 5, 6
• Classic GAS pharyngitis presents with acute onset of fever, sore throat, headache, and may include a scarlatiniform (sandpaper) rash. 4, 6
• Physical examination typically reveals tonsillopharyngeal erythema, tender enlarged anterior cervical lymph nodes, and the characteristic sandpaper-textured rash. 4, 6

Alternative Treatment Options (If Penicillin Allergy)

For non-anaphylactic penicillin allergy:

• First-generation cephalosporins (cephalexin 20 mg/kg twice daily for 10 days) are the preferred alternatives with strong, high-quality evidence. 7, 2

For immediate/anaphylactic penicillin allergy:

• Clindamycin 7 mg/kg three times daily (maximum 300 mg/dose) for 10 days is the preferred choice, with only ~1% resistance in the US. 7, 2
• Azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days is acceptable but has 5-8% macrolide resistance rates. 7, 2, 8

Common Pitfalls to Avoid

• Do not use Augmentin (amoxicillin-clavulanate) as first-line therapy - it unnecessarily broadens the spectrum, increases cost, and promotes resistance without providing additional benefit for uncomplicated GAS infections. 1, 2
• Do not stop treatment early despite clinical improvement - symptoms typically resolve within 3-4 days, but bacteriologic eradication requires the full 10-day course to prevent rheumatic fever. 1, 2
• Do not prescribe trimethoprim-sulfamethoxazole (Bactrim) - it has high resistance rates (~50%) and is not effective for GAS. 7
• Do not perform routine post-treatment throat cultures for asymptomatic patients who have completed therapy. 7, 2

Goals of Treatment

• Primary goal: Prevention of acute rheumatic fever, which requires adequate bacterial eradication. 2, 3, 6
• Secondary goals include prevention of suppurative complications (peritonsillar abscess, cervical lymphadenitis), rapid decrease in infectivity to reduce transmission, and improvement in clinical symptoms. 4, 2, 6

When to Consider Diagnostic Testing

• While the sandpaper rash is highly suggestive of scarlet fever, confirmation with rapid antigen detection test (RADT) or throat culture is recommended before initiating antibiotics if the diagnosis is uncertain. 4, 9, 6
• Most rapid antigen detection tests have excellent specificity (>95%) and sensitivity (≥90%), with results available in less than 15 minutes. 9