What is the appropriate treatment for impetigo in a 7‑year‑old girl?

Treatment of Impetigo in a 7-Year-Old Girl

For this 7-year-old with impetigo, start with topical mupirocin 2% ointment applied three times daily for 5-7 days to the affected areas. 1, 2

First-Line Treatment: Topical Antibiotics

• Mupirocin 2% ointment is the gold standard first-line treatment for limited impetigo (lesions covering up to 100 cm² total area), applied three times daily for 5-7 days. 1, 2
• Before each application, gently wash the affected area with soap and water to remove crusts and enhance antibiotic penetration. 1
• Retapamulin 1% ointment is an effective alternative, applied twice daily for 5 days if mupirocin is unavailable or not tolerated. 1, 3
• Topical therapy is preferred over oral antibiotics for limited disease because it delivers high drug concentrations directly to the infection site with fewer systemic adverse effects. 4, 5

When to Switch to Oral Antibiotics

Oral antibiotics are indicated when any of the following criteria are met: 1, 3

• Extensive disease (multiple lesions across large body surface areas or involving multiple sites)
• Topical therapy is impractical (patient unable to apply medication properly, poor adherence expected)
• Failure of topical treatment after 48-72 hours with no improvement
• Systemic symptoms present (fever, malaise, lymphadenopathy)

Oral Antibiotic Options for Methicillin-Susceptible S. aureus (MSSA):

• Cephalexin (first-generation cephalosporin): 25-50 mg/kg/day divided into 3-4 doses for 7 days 1, 4
• Dicloxacillin: 12.5-25 mg/kg/day divided into 4 doses for 7 days 1, 4
• Amoxicillin-clavulanate is an acceptable alternative 1
• Never use penicillin alone as it lacks adequate coverage against S. aureus, the primary pathogen. 3, 4

Community-Acquired MRSA Considerations

Consider empiric MRSA coverage if: 6, 1

• The patient is at high risk for CA-MRSA (previous MRSA infection, household contact with MRSA, participation in contact sports)
• No response to first-line therapy after 48-72 hours
• High local prevalence of CA-MRSA in your community

MRSA-Active Oral Antibiotics:

• Clindamycin: 10-20 mg/kg/day divided into 3 doses (maximum 300-450 mg per dose) 1, 3
• Trimethoprim-sulfamethoxazole (TMP-SMX): 8-12 mg/kg/day (based on trimethoprim component) divided into 2 doses 1, 3
• Doxycycline: NOT appropriate for this 7-year-old as tetracyclines should not be used in children under 8 years due to tooth discoloration risk 3

Important caveat: TMP-SMX does not adequately cover streptococcal infections, so use it only when MRSA is confirmed by culture or streptococcal infection is definitively ruled out. 7, 4

Infection Control Measures

These are critical to prevent household transmission: 1

• Keep the child home from school and daycare for at least 24 hours after starting antibiotic treatment
• Trim fingernails short to reduce scratching and spread
• Wash all clothing, towels, and bedding in hot water daily during the first few days of treatment
• Do not share personal items (towels, washcloths, clothing) with other household members
• Encourage frequent handwashing with soap and water, especially after touching lesions
• Examine siblings and close contacts for new lesions, as impetigo spreads easily within families

Follow-Up and Warning Signs

• Reassess at 48-72 hours: If no improvement, consider MRSA coverage or obtain cultures to guide therapy. 1, 7
• Complete the full antibiotic course even if symptoms improve quickly to prevent complications such as post-streptococcal glomerulonephritis. 1
• Seek immediate evaluation if fever develops or worsens during treatment, or if redness expands beyond the original lesions. 1

Treatment Algorithm Summary

1. Limited impetigo → Topical mupirocin 2% TID × 5-7 days 1, 2
2. Extensive disease or topical failure → Oral cephalexin or dicloxacillin × 7 days 1, 4
3. Suspected MRSA or treatment failure → Clindamycin or TMP-SMX (with culture confirmation) × 7 days 1, 3
4. Always implement infection control measures regardless of treatment choice 1