What is the next step in treating impetigo that is refractory to mupirocin (Bactroban)?

Treatment of Impetigo Refractory to Mupirocin

For impetigo that is refractory to mupirocin treatment, oral antibiotics such as dicloxacillin, cephalexin, clindamycin, or amoxicillin-clavulanate should be initiated as the next step in management. 1

Assessment of Mupirocin Failure

When impetigo fails to respond to mupirocin after 3-5 days of proper application, consider the following:

• Evaluate for proper medication use - mupirocin should be applied three times daily to affected areas 2
• Consider possible mupirocin resistance, which has been increasingly documented 1, 3
• Assess for potential MRSA infection, especially in areas with high MRSA prevalence 1, 4
• Rule out deeper infection or alternative diagnosis if clinical presentation is atypical 1

Recommended Oral Antibiotic Options

First-line oral antibiotics (for presumed methicillin-susceptible S. aureus):

• Dicloxacillin: 250 mg four times daily for adults; 12 mg/kg/day in 4 divided doses for children 1
• Cephalexin: 250-500 mg four times daily for adults; 25 mg/kg/day in 4 divided doses for children 1
• Amoxicillin-clavulanate: 875/125 mg twice daily for adults; 25 mg/kg/day of amoxicillin component in 2 divided doses for children 1

For suspected or confirmed MRSA infection:

• Clindamycin: 300-450 mg three times daily for adults; 10-20 mg/kg/day in 3 divided doses for children 1
• Trimethoprim-sulfamethoxazole (TMP-SMX): 1-2 double-strength tablets twice daily for adults; 8-12 mg/kg/day (based on trimethoprim component) in 2 divided doses for children 1, 3
• Doxycycline: 100 mg twice daily (not recommended for children under 8 years) 1, 3

Treatment Algorithm

1. Confirm diagnosis and rule out complications:

   • Verify the diagnosis is indeed impetigo (honey-colored crusts for non-bullous; large, flaccid bullae for bullous impetigo) 4, 3
   • Consider obtaining cultures if treatment failure occurs or MRSA is suspected 1

2. Select appropriate oral antibiotic:

   • For areas with low MRSA prevalence: Dicloxacillin or cephalexin 1
   • For areas with high MRSA prevalence: Clindamycin, TMP-SMX, or doxycycline 1, 3
   • For penicillin-allergic patients: Clindamycin or macrolides (noting potential resistance) 1

3. Treatment duration:

   • Continue oral antibiotics for 7 days 3, 5
   • Re-evaluate if no improvement after 48-72 hours of oral therapy 1

Important Considerations and Caveats

• Penicillin alone is not effective for impetigo as it lacks adequate coverage against S. aureus 4, 3
• Macrolides (e.g., erythromycin) may have increasing resistance rates and should be used with caution 1, 3
• For extensive impetigo, systemic therapy is preferred over topical treatment 1, 5
• Consider alternative topical agents like retapamulin if available, particularly for limited lesions where topical therapy is still appropriate 4, 5
• In cases of recurrent impetigo, consider decolonization strategies for S. aureus carriers 1

Special Populations

• For pregnant patients: Cephalexin is generally considered safe; avoid tetracyclines 1
• For children under 8 years: Avoid doxycycline and other tetracyclines 1
• For patients with extensive disease: Systemic antibiotics are preferred over topical therapy 1, 5