What is the treatment for impetigo?

Treatment of Impetigo

For limited impetigo, use topical mupirocin 2% ointment three times daily for 5-7 days as first-line therapy; for extensive disease, multiple lesions, or when topical therapy is impractical, use oral antibiotics such as dicloxacillin or cephalexin for 7-10 days. 1, 2

First-Line Treatment: Topical Antibiotics for Limited Disease

• Mupirocin 2% ointment applied three times daily for 5-7 days is the preferred first-line treatment for localized impetigo 1, 3
• Retapamulin 1% ointment applied twice daily for 5 days is an FDA-approved alternative for patients 9 months or older 1, 4
• Topical antibiotics demonstrate superior cure rates compared to placebo (RR 2.24,95% CI 1.61-3.13) and are equally or more effective than oral antibiotics for limited disease 5
• Mupirocin and fusidic acid show equivalent efficacy, with no significant difference in cure rates (RR 1.03,95% CI 0.95-1.11) 5

Second-Line Treatment: Oral Antibiotics for Extensive Disease

Oral antibiotics are indicated when:

• Impetigo is extensive or involves multiple body sites 1, 2
• Topical therapy is impractical (e.g., scalp involvement, large surface area) 1, 2
• Topical treatment has failed after 48-72 hours 2
• Systemic symptoms are present 1

Oral Antibiotic Selection

For methicillin-susceptible S. aureus (MSSA):

• Dicloxacillin 250 mg four times daily for adults 2
• Cephalexin 250-500 mg four times daily for adults 2
• Treatment duration: 7-10 days 2

For suspected or confirmed MRSA:

• Clindamycin 300-450 mg three times daily for adults 2
• Trimethoprim-sulfamethoxazole (TMP-SMX) 1, 2
• Doxycycline (avoid in children under 8 years) 1, 2

Comparative Efficacy of Oral Antibiotics

• Topical mupirocin is slightly superior to oral erythromycin (RR 1.07,95% CI 1.01-1.13) 5
• Penicillin alone is inferior to erythromycin (RR 1.29,95% CI 1.07-1.56) and cloxacillin (RR 1.59,95% CI 1.21-2.08), and should not be used as it lacks adequate S. aureus coverage 2, 5

Special Considerations for MRSA

• Consider empiric MRSA coverage in patients with: 1
  • Failure to respond to first-line therapy
  • High local prevalence of community-acquired MRSA
  • Known risk factors for CA-MRSA infection
• Obtain cultures from vesicle fluid, pus, or erosions if treatment failure occurs, MRSA is suspected, or in recurrent infections 2

Treatment Duration and Monitoring

• Complete the full antibiotic course even if symptoms improve quickly to prevent complications such as post-streptococcal glomerulonephritis 1
• Reassess at 48-72 hours; if no improvement, consider MRSA coverage or alternative diagnosis 2
• Topical treatment: 5-7 days 2
• Oral antibiotics: 7-10 days 2

Critical Pitfalls to Avoid

• Never use penicillin alone for impetigo—it lacks adequate S. aureus coverage 2
• Do not use topical disinfectants as they are inferior to antibiotics (RR 1.15,95% CI 1.01-1.32 favoring topical antibiotics) 5
• Avoid TMP-SMX monotherapy unless streptococcal infection is definitively ruled out by culture, as it provides inadequate streptococcal coverage 6
• Do not add rifampin as adjunctive therapy—it is not recommended for skin and soft tissue infections 6
• Adjust oral antibiotic dosing by weight for children 2
• Keep lesions covered with clean, dry bandages to prevent spread 2

Antimicrobial Resistance Considerations

• Growing worldwide resistance to commonly used antibiotics necessitates culture-guided therapy when first-line treatment fails 7
• Methicillin-resistant S. aureus, macrolide-resistant streptococcus, and mupirocin-resistant streptococcus are all documented 8
• Fusidic acid, mupirocin, and retapamulin cover methicillin-susceptible S. aureus and streptococcal infections 8