What oral antibiotics are recommended for treating bullous impetigo?

Oral Antibiotics for Bullous Impetigo

For bullous impetigo, first-line oral antibiotic therapy should be dicloxacillin, cephalexin, or amoxicillin-clavulanate for 7 days, with clindamycin, trimethoprim-sulfamethoxazole, or doxycycline as alternatives for suspected MRSA infections. 1

First-Line Oral Antibiotic Options

For Methicillin-Susceptible S. aureus (MSSA):

• Dicloxacillin: 500 mg four times daily for 7 days 2
• Cephalexin: 500 mg twice daily for 7 days 2
• Amoxicillin-clavulanate: 875/125 mg twice daily for 7 days 3, 1

For Suspected or Confirmed MRSA:

• Clindamycin: 300 mg three times daily for 7 days 3, 1
• Trimethoprim-sulfamethoxazole (SMX-TMP): 160-800 mg twice daily for 7 days 1, 4
• Doxycycline: 100 mg twice daily for 7 days (not recommended for children under 8 years) 1, 4

Treatment Algorithm

1. Obtain cultures from active lesions before starting antibiotics to identify the causative organism and antibiotic sensitivities 1

2. Initial antibiotic selection:

   • For typical cases without risk factors for MRSA: Start dicloxacillin or cephalexin
   • For patients with risk factors for MRSA (prior MRSA infection, local high prevalence, failure of beta-lactam therapy): Start clindamycin, SMX-TMP, or doxycycline

3. Evaluate response within 48-72 hours:

   • If improving: Complete 7-day course
   • If not improving within 3-5 days: Consider alternative antibiotics based on culture results or switch to MRSA-active agent 1

4. For extensive disease: Oral antibiotics are preferred over topical therapy 4, 5

Special Considerations

• Penicillin alone is not effective for bullous impetigo as most S. aureus strains are resistant 4, 5
• Children: Adjust dosing by weight; avoid doxycycline in children under 8 years 3
• Pregnancy: Cephalexin is generally considered safe; avoid trimethoprim-sulfamethoxazole in late pregnancy 1

Common Pitfalls to Avoid

• Failing to consider MRSA in recalcitrant cases 1
• Using penicillin alone, which is ineffective against most S. aureus 4
• Inadequate duration of therapy (standard is 7 days) 1
• Relying solely on topical therapy for extensive bullous impetigo 4
• Not addressing underlying conditions that may predispose to recurrent infection 1

Prevention of Recurrence

For patients with recurrent infections (3-4 episodes per year), consider:

• 5-day decolonization regimen with intranasal mupirocin twice daily
• Daily chlorhexidine washes
• Daily decontamination of personal items 1

Bullous impetigo typically resolves within 7-10 days with appropriate antibiotic therapy, and complications are rare 1, 4.