What is the recommended treatment for impetigo in a child, including first‑line topical and oral antibiotics, dosing, methicillin‑resistant Staphylococcus aureus (MRSA) coverage, and special considerations for infants under two months?

Recommended Treatment for Impetigo in Children

First-Line Treatment Based on Disease Extent

For limited impetigo (few lesions), topical mupirocin 2% ointment applied twice daily for 5 days is the first-line treatment, while extensive disease requires oral cephalexin 25-50 mg/kg/day divided into 4 doses for 7 days. 1

Topical Therapy for Limited Disease

• Mupirocin 2% ointment applied twice daily (or three times daily per some protocols) for 5 days is highly effective for limited impetigo and achieves cure rates 6-fold higher than placebo. 1, 2
• Retapamulin 1% ointment applied twice daily for 5 days is an alternative for patients aged 9 months or older, covering up to 2% total body surface area in children. 1
• Topical therapy may be superior to oral antibiotics for limited disease. 1, 3

When to Switch to Oral Antibiotics

• Use oral antibiotics when impetigo is extensive (numerous lesions), not responding to topical therapy after 3-5 days, associated with systemic symptoms, or involves the face/eyelid/mouth. 1, 2
• Oral therapy is recommended during outbreaks to decrease transmission. 1

Oral Antibiotic Options for Extensive Disease

First-Line Oral Antibiotics (Presumed MSSA)

• Cephalexin syrup: 25-50 mg/kg/day divided into 4 doses for 7 days 1
• Dicloxacillin syrup: 25-50 mg/kg/day divided into 4 doses for 7 days 1
• Co-amoxiclav (amoxicillin-clavulanic acid) is an acceptable alternative providing coverage for both S. aureus and S. pyogenes. 1

MRSA Coverage When Suspected

• Clindamycin syrup: 20-30 mg/kg/day divided into 3 doses for 7 days 1
• Sulfamethoxazole-trimethoprim (SMX-TMP) syrup: 8-12 mg/kg/day (based on trimethoprim component) divided into 2 doses for 7 days 1
• Doxycycline syrup: 2-4 mg/kg/day divided into 2 doses for 7 days (only for children over 8 years old) 1
• In areas with high MRSA prevalence, empiric therapy should cover MRSA until culture results are available. 1

Critical Pitfall: Avoid Ineffective Antibiotics

• Penicillin alone is seldom effective and should only be used when cultures confirm streptococci alone. 1
• Amoxicillin alone should not be used because it lacks adequate coverage against S. aureus, which is now the predominant causative organism. 1
• Cefdinir should not be used when MRSA is suspected, documented, or confirmed. 1

Special Considerations for Infants Under Two Months

• Retapamulin is approved for patients aged 9 months or older, so it should not be used in infants under 2 months. 1
• For bullous impetigo in infants, which is exclusively caused by toxin-producing S. aureus, systemic therapy with oral or intravenous flucloxacillin is first-line treatment. 4
• Topical fusidic acid or mupirocin can be used for limited disease in infants. 4
• Lower threshold for systemic antibiotics and hospital admission should be considered in infants, particularly neonates with extensive disease or systemic signs. 1, 4
• Nasal swabs from the patient and immediate relatives should be performed to identify asymptomatic nasal carriers of S. aureus in infant cases. 4

Penicillin Allergy Management

• For patients with penicillin allergy, cephalexin (first-generation cephalosporin) can be used except in those with immediate hypersensitivity reactions (anaphylaxis/hives). 1
• Clindamycin 20-30 mg/kg/day in 3 divided doses is the preferred alternative for penicillin-allergic patients. 1, 2
• Macrolides can be used, though resistance rates to erythromycin are rising. 5

Age-Specific Precautions

• Tetracyclines (doxycycline) should be avoided in children under 8 years due to the risk of permanent dental staining. 1

Infection Control Measures

• Keep lesions covered with clean, dry bandages to prevent spread. 1
• Maintain good personal hygiene with regular handwashing. 1
• Avoid sharing personal items that contact the skin (towels, equipment). 1
• Athletes should be excluded from participation until 24 hours after initiation of effective antimicrobial therapy, and skin lesions must be covered. 1

Treatment Duration

• Topical antibiotics: 5 days 1
• Oral antibiotics: 7 days (not the shorter 5-day course used for topical agents) 1

When to Obtain Cultures

• Cultures are not routinely necessary for typical cases of limited impetigo. 1
• Obtain cultures when there is treatment failure, MRSA is suspected, recurrent infections occur, or in immunocompromised patients. 1, 2

Monitoring and Follow-Up

• If no improvement occurs by 3-5 days of appropriate therapy, reassess for MRSA infection requiring alternative antibiotics, deeper infection, non-compliance, or antibiotic resistance. 1

Outbreak Management

• During outbreaks of poststreptococcal glomerulonephritis, systemic antimicrobials should be used to eliminate nephritogenic strains of S. pyogenes from the community. 1
• Consider decolonization strategies using topical nasal mupirocin therapy for S. aureus carriers during outbreaks. 1