What is the appropriate treatment for impetigo?

Treatment of Impetigo

For limited impetigo (few lesions), topical mupirocin is the best first-line treatment, while patients with numerous lesions or those not responding to topical therapy should receive oral antibiotics effective against both S. aureus and S. pyogenes. 1

Treatment Algorithm Based on Disease Extent

Limited Disease (Few Lesions)

• Topical mupirocin ointment applied 3 times daily is the preferred agent with the strongest evidence (A-I recommendation) 1
• Alternative topical option: Retapamulin ointment applied twice daily 2
• Bacitracin and neomycin are considerably less effective and should be avoided 1

Important caveat: The decision to use topical versus systemic therapy depends on:

• Number of lesions present
• Location (face, eyelid, or mouth involvement)
• Need to limit spread to others 1

Widespread Disease or Topical Treatment Failure

Oral antibiotic options (must cover both S. aureus and S. pyogenes):

First-line choices 1, 2:

• Dicloxacillin 250 mg four times daily (adults) or 12 mg/kg/day in 4 divided doses (children)
• Cephalexin 250 mg four times daily (adults) or 25-50 mg/kg/day in 3-4 divided doses (children)
• Amoxicillin-clavulanate 875/125 mg twice daily (adults) or 25 mg/kg/day in 2 divided doses (children)

Alternative options:

• Clindamycin 300-400 mg three times daily (adults) or 20 mg/kg/day in 3 divided doses (children) 1, 2
• Erythromycin 250 mg four times daily (adults) or 40 mg/kg/day in 4 divided doses (children) - but note increasing resistance: macrolide resistance in S. pyogenes has risen from 4-5% to 8-9%, though 99.5% remain susceptible to clindamycin and 100% to penicillin 1

Pediatric-Specific Considerations

For children with minor skin infections like impetigo, mupirocin 2% topical ointment is recommended (A-III) 3, 4

Critical restriction: Tetracyclines (doxycycline, minocycline) should NOT be used in children <8 years of age (A-II) 3, 4

Addressing MRSA Concerns

While most impetigo in typical community settings is caused by methicillin-susceptible S. aureus (MSSA), if MRSA is suspected or confirmed:

Oral options for MRSA coverage 3:

• Clindamycin (if local resistance <10%)
• Trimethoprim-sulfamethoxazole (TMP-SMX) - note this lacks streptococcal coverage and should be combined with a β-lactam like amoxicillin if streptococcal infection is possible 3, 4
• Doxycycline or minocycline (not in children <8 years)
• Linezolid

Common Pitfalls to Avoid

1. Penicillin alone is inadequate - it lacks activity against S. aureus and showed inferior cure rates compared to other antibiotics 1, 5

2. Disinfectant solutions lack evidence - topical antibiotics are significantly better than disinfecting treatments (RR 1.15,95% CI 1.01-1.32) 5

3. Resistance patterns matter - mupirocin resistance has been described, and local resistance patterns should guide therapy when known 1

4. Treatment does NOT prevent post-streptococcal glomerulonephritis - although this complication is rare (<1 case/1,000 population per year in developed countries), no data demonstrate that treating impetigo prevents this sequela 1

Duration of Therapy

Treatment duration should be 5-10 days but individualized based on clinical response 3. Most cases resolve within 2-3 weeks without scarring 6.

When to Culture

Cultures are not routinely necessary for typical impetigo but should be obtained if 7:

• Severe local infection or systemic illness present
• Inadequate response to initial treatment
• Concern for outbreak or cluster