What is the treatment for impetigo?

Treatment of Impetigo

For impetigo treatment, topical mupirocin 2% ointment applied three times daily for 7-10 days is the first-line therapy for limited disease, while oral antibiotics such as cephalexin or clindamycin for 7 days are recommended for extensive or bullous impetigo. 1

Types of Impetigo and Causative Organisms

Impetigo presents in two main forms:

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

Treatment Algorithm

1. Limited Disease (Few Lesions)

• First-line: Topical mupirocin 2% ointment applied three times daily for 7-10 days 1, 3
  • Clinical efficacy rates of 71-93% have been demonstrated 3
  • Effective against both S. aureus and S. pyogenes 3
• Alternatives: Retapamulin or fusidic acid (where available) 1

2. Extensive Disease or Bullous Impetigo

• First-line oral antibiotics (7-day course):
  • For MSSA: Dicloxacillin or cephalexin 1
  • For confirmed streptococcal infection: Oral penicillin 1
  • For suspected MRSA: Clindamycin 300mg three times daily 1

3. Special Considerations

• For suspected MRSA: Clindamycin is preferred due to excellent coverage against both MRSA and streptococci 1
• Avoid: Trimethoprim-sulfamethoxazole for streptococcal infections (inadequate coverage) 1, 2
• Avoid: Tetracyclines (doxycycline, minocycline) in children under 8 years 1
• Avoid: Penicillin as monotherapy (inferior efficacy) 1, 2

Evidence-Based Efficacy

Topical mupirocin has demonstrated:

• 71% clinical efficacy rate compared to 35% for vehicle placebo 3
• 94% pathogen eradication rate compared to 62% for vehicle placebo 3
• 93% clinical efficacy rate compared to 78.5% for oral erythromycin 3
• 100% pathogen eradication rate in comparative studies 3

Multiple studies have shown that topical antibiotics (mupirocin and fusidic acid) are equally or more effective than oral antibiotics for limited impetigo 1, 4.

Treatment Monitoring and Expected Outcomes

• Evaluate clinical response within 48-72 hours of starting treatment 1
• Expected resolution within 7-10 days with appropriate antibiotics 1
• If no improvement is seen within 3-5 days:
  • Consider bacterial culture and sensitivity testing
  • Evaluate for alternative diagnosis
  • Consider need for intravenous antibiotics 1

Common Pitfalls to Avoid

1. Failure to consider MRSA in recalcitrant cases 1
2. Using penicillin monotherapy, which has inferior efficacy 1, 2
3. Using trimethoprim-sulfamethoxazole alone for potential streptococcal infections 1, 2
4. Inadequate duration of therapy (less than 7 days) 1
5. Relying solely on topical therapy for extensive disease 1
6. Using topical disinfectants, which are inferior to antibiotics and should not be used 2, 4
7. Not addressing underlying conditions that may predispose to recurrent infection 1

Prevention Measures

• Keep lesions covered when possible
• Use separate towels and linens
• Practice good hand hygiene
• Prompt identification and treatment of cases to prevent spread 1

Antimicrobial resistance is an increasing concern, particularly with community-acquired MRSA becoming more prevalent as an etiological agent of impetigo 1, 5. Treatment selection should consider local resistance patterns when available.