Mupirocin is the Preferred First-Line Treatment for Non-Extensive Impetigo
For non-extensive impetigo, mupirocin 2% ointment applied three times daily is the recommended first-line treatment, with fusidic acid (fusidin) not being a guideline-recommended option in major infectious disease guidelines. 1, 2
Evidence-Based Rationale
Mupirocin as First-Line Therapy
The Infectious Diseases Society of America explicitly recommends mupirocin 2% ointment applied three times daily as the most effective topical agent for impetigo caused by S. aureus and S. pyogenes 1
The FDA has approved mupirocin ointment 2% specifically for topical treatment of impetigo due to Staphylococcus aureus and Streptococcus pyogenes 2
Clinical trials demonstrate that mupirocin achieves 71-93% clinical efficacy rates in impetigo, with 94-100% pathogen eradication rates 2
In pediatric populations (ages 2 months to 15 years), mupirocin achieved 78-96% clinical efficacy rates, significantly superior to vehicle placebo (36%) 2
Why Not Fusidic Acid?
Fusidic acid (fusidin) is notably absent from current Infectious Diseases Society of America and American Academy of Pediatrics guidelines for impetigo treatment 3, 1
The major U.S. clinical guidelines reviewed do not list fusidic acid as a recommended topical agent for impetigo, focusing instead on mupirocin as the primary topical option 1
Fusidic acid is not FDA-approved in the United States for impetigo treatment, limiting its availability and evidence base in North American practice 2
Treatment Algorithm for Non-Extensive Impetigo
Initial Assessment
- Confirm diagnosis clinically (honey-crusted lesions, limited distribution) 1
- Determine extent: non-extensive = localized lesions without systemic symptoms 1
First-Line Treatment
- Apply mupirocin 2% ointment three times daily to affected areas for 5-7 days 1, 2
- Keep lesions covered with clean, dry bandages 1
When to Switch to Oral Antibiotics
- No improvement after 3-5 days of topical therapy 1
- Extensive disease develops 1
- Systemic symptoms appear (fever, malaise) 1
- Lesions involve face, eyelid, or mouth 1
Oral Antibiotic Options (if needed)
- For presumed MSSA: dicloxacillin 250 mg four times daily or cephalexin 250-500 mg four times daily 1
- For suspected MRSA: clindamycin 300-450 mg three times daily or trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily 1
Important Clinical Considerations
Common Pitfalls to Avoid
- Do not use bacitracin or neomycin—these are considerably less effective than mupirocin and should not be used for impetigo 1
- Do not use topical clindamycin cream (the acne formulation), as it lacks FDA indication for impetigo and has insufficient bioavailability 1
- Penicillin alone is not effective for impetigo due to inadequate S. aureus coverage 1, 4
When to Obtain Cultures
- Treatment failure with mupirocin 1, 4
- MRSA suspected (recurrent infections, known colonization) 1
- Atypical presentation or no improvement after 48-72 hours of oral therapy 4