What is the treatment for impetigo?

Impetigo Treatment

Topical mupirocin is the first-line treatment for limited impetigo lesions, while oral antibiotics are indicated for extensive disease or when topical therapy is impractical. 1

Types and Causes of Impetigo

Impetigo presents in two main forms:

• Nonbullous impetigo (70% of cases):

  • Caused by Staphylococcus aureus or Streptococcus pyogenes
  • Characterized by honey-colored crusts on erythematous base
  • Typically affects face and extremities 2, 3

• Bullous impetigo (30% of cases):

  • Caused exclusively by S. aureus
  • Presents with large, flaccid bullae
  • More likely to affect intertriginous areas 3

Treatment Algorithm

1. Limited Lesions (First-Line)

• Topical mupirocin 2% ointment applied three times daily for 7-10 days 1
  • Clinical efficacy rates of 71-93% 4
  • Pathogen eradication rates of 94-100% 4
  • As effective as oral antibiotics with fewer side effects 4

2. Alternative Topical Options

• Retapamulin or fusidic acid (where available) 1
  • Particularly useful for methicillin-susceptible S. aureus and streptococcal infections 3

3. Indications for Oral Antibiotics

• Numerous or extensive lesions
• Failure to respond to topical therapy
• Impractical application of topical agents 1

4. Oral Antibiotic Options

• First-line oral options:

  • Penicillinase-resistant semisynthetic penicillins (dicloxacillin)
  • First-generation cephalosporins (cephalexin) 1

• For penicillin-allergic patients:

  • Clindamycin
  • Macrolides (erythromycin)
  • Doxycycline (for patients >8 years old) 2

• For suspected/confirmed MRSA:

  • Trimethoprim-sulfamethoxazole (note: inadequate for streptococcal coverage)
  • Clindamycin 1, 3

Important Clinical Considerations

• Duration of therapy:

  • Topical therapy: 5-7 days
  • Oral therapy: 7-10 days 2

• Follow-up:

  • Re-evaluate within 24-48 hours if using tetracyclines or trimethoprim-sulfamethoxazole to verify clinical response 1

• Complications:

  • Poststreptococcal glomerulonephritis is rare (<1 case/1,000 population per year)
  • Note that antibiotic treatment has not been proven to prevent this complication 1, 5

Common Pitfalls to Avoid

1. Ineffective treatments:

   • Topical disinfectants are inferior to antibiotics and should not be used 3, 6
   • Oral penicillin V is seldom effective for impetigo 6

2. Antibiotic resistance concerns:

   • Consider local resistance patterns when selecting therapy
   • Methicillin-resistant S. aureus, macrolide-resistant streptococci, and mupirocin-resistant strains are increasingly documented 3

3. Inadequate coverage:

   • Trimethoprim-sulfamethoxazole covers MRSA but is inadequate for streptococcal infections 3
   • Unless cultures yield streptococci alone, antimicrobial therapy should be active against both S. aureus and streptococci 2

4. Compliance issues:

   • Consider patient preference and ability to adhere to treatment when choosing between topical and oral options 7
   • Systemic therapy is preferred for patients with numerous lesions or in outbreaks affecting several people to help decrease transmission 2