What is the treatment for impetigo?

Treatment of Impetigo

Topical mupirocin 2% ointment applied three times daily for 5-7 days is the first-line treatment for limited impetigo lesions, while oral antibiotics are indicated for extensive disease or when topical therapy is impractical. 1

Clinical Presentation and Diagnosis

Impetigo presents in two main forms:

• Nonbullous impetigo (70% of cases): Caused by Staphylococcus aureus or Streptococcus pyogenes, characterized by honey-colored crusts on an erythematous base, typically affecting the face and extremities 1, 2
• Bullous impetigo (30% of cases): Caused exclusively by S. aureus, presents with large, flaccid bullae, more likely to affect intertriginous areas 1, 2

Diagnosis is primarily clinical based on the characteristic appearance of lesions.

Treatment Algorithm

1. Limited Impetigo (Few Lesions)

• First-line: Topical mupirocin 2% ointment applied three times daily for 5-7 days 1, 3
  • Clinical efficacy rates of 71-93% documented in controlled trials 3
  • Pathogen eradication rates of 94-100% 3
• Alternative topical options: Retapamulin or fusidic acid 1

2. Extensive Impetigo or When Topical Therapy is Impractical

• First-line oral options (7-10 day course): 1
  • Penicillinase-resistant semisynthetic penicillins (dicloxacillin)
  • First-generation cephalosporins (cephalexin)
• For penicillin-allergic patients:
  • Clindamycin
  • Macrolides (erythromycin)
  • Doxycycline (for patients >8 years old)

3. Suspected or Confirmed MRSA

• Topical mupirocin may still be effective against many MRSA strains 1
• If oral therapy needed:
  • Trimethoprim-sulfamethoxazole (note: inadequate streptococcal coverage) 1
  • Clindamycin 1

4. Hospitalized Children with Complicated Infections

• First choice: Vancomycin 1
• Alternatives: Clindamycin, linezolid 1

Evidence-Based Insights

Topical mupirocin has been shown to be equally or more effective than oral antibiotics for limited disease:

• Clinical studies demonstrate comparable or superior efficacy to oral erythromycin 3, 4
• Topical treatment causes fewer side effects than oral antibiotics 5

The FDA-approved clinical studies for mupirocin ointment showed:

• 71% clinical efficacy rate versus 35% for vehicle placebo 3
• 93% clinical efficacy rate versus 78.5% for oral erythromycin 3
• 100% pathogen eradication rate in evaluable patients 3

Special Considerations and Pitfalls

• Do not use penicillin V as it is seldom effective against impetigo 1, 6
• Avoid tetracyclines (doxycycline, minocycline) in children under 8 years due to risk of inhibiting bone growth 1
• Mupirocin should not be used in infants with moderate or severe renal impairment due to risk of polyethylene glycol absorption 1
• Topical disinfectants are inferior to antibiotics and should not be used 5, 6
• Re-evaluate in 24-48 hours if using tetracyclines or trimethoprim-sulfamethoxazole to verify clinical response 1
• If no improvement within 3-5 days, reassess diagnosis and consider alternative antibiotics 1

Prevention of Spread

• Keep lesions covered when possible
• Use separate towels and linens for infected individuals
• Practice good hand hygiene
• Systemic therapy is preferred for outbreaks affecting several people to decrease transmission 1

Impetigo typically resolves within 7-10 days with appropriate treatment. Complications are rare, with poststreptococcal glomerulonephritis being the most serious but uncommon (<1 case/1,000 population per year) 1.