What is the recommended treatment for bullous impetigo?

Treatment of Bullous Impetigo

First-Line Treatment Recommendation

For bullous impetigo, initiate a 7-day course of oral cephalexin (25-50 mg/kg/day divided into 4 doses for children; 250-500 mg four times daily for adults) or dicloxacillin as first-line therapy, targeting methicillin-susceptible Staphylococcus aureus. 1, 2

Understanding Bullous Impetigo

• Bullous impetigo is exclusively caused by toxin-producing Staphylococcus aureus that produces exfoliative toxins cleaving desmoglein-1, resulting in large, flaccid bullae 2, 3, 4
• This represents approximately 30% of all impetigo cases and more commonly affects intertriginous areas 3, 4
• Most isolates are methicillin-susceptible S. aureus (MSSA), making beta-lactam antibiotics the preferred choice 1, 5

Treatment Algorithm

For Presumed MSSA (Most Common Scenario)

Oral antibiotic options (7-day course): 1, 2

• Cephalexin: 25-50 mg/kg/day divided into 4 doses (children) or 250-500 mg four times daily (adults) 1, 2, 6
• Dicloxacillin: 25-50 mg/kg/day divided into 4 doses (children) or 250 mg four times daily (adults) 1, 2, 6

When MRSA is Suspected or Confirmed

Switch to MRSA-active agents: 1, 2

• Clindamycin: 20-30 mg/kg/day divided into 3 doses (children) or 300-450 mg three times daily (adults) 1, 2, 6
• Trimethoprim-sulfamethoxazole (TMP-SMX): 8-12 mg/kg/day (based on trimethoprim) divided into 2 doses (children) or 1-2 double-strength tablets twice daily (adults) 1, 2, 6
• Doxycycline (only for children >8 years): 2-4 mg/kg/day divided into 2 doses 1, 2

Topical Therapy Considerations

• Mupirocin 2% ointment applied three times daily is FDA-approved for impetigo and showed 71% clinical efficacy versus 35% for placebo 7
• However, topical therapy alone is generally not recommended for bullous impetigo due to the systemic nature of toxin-mediated disease and extent of involvement 6, 3
• Topical agents may be considered only for very localized disease, but oral antibiotics remain preferred 2, 6

Critical Clinical Considerations

Treatment Duration and Monitoring

• All oral antibiotic regimens should be 7 days in duration 1, 2
• Clinical improvement should occur within 24-48 hours of appropriate antibiotic therapy 5
• If no improvement after 3-5 days, obtain cultures and consider MRSA coverage 6

Important Pitfalls to Avoid

• Never use penicillin alone - it lacks adequate coverage against S. aureus and is ineffective for impetigo 6, 3
• Avoid tetracyclines (doxycycline) in children under 8 years due to risk of permanent dental staining 2, 6
• Be aware that bullous impetigo in children with atopic dermatitis is frequently misdiagnosed as an AD flare, leading to delayed treatment 5
• In areas with high MRSA prevalence, empiric MRSA coverage should be initiated until culture results are available 2

Antibiotic Resistance Patterns

• Recent data shows clindamycin resistance in approximately 25% of MSSA strains in some populations 5
• Cephalosporins are recommended over clindamycin for uncomplicated disseminated bullous impetigo given emerging clindamycin resistance 5
• Erythromycin resistance rates are rising and this agent should be avoided 2, 3

Special Populations

Penicillin-Allergic Patients

• Clindamycin is the preferred alternative for patients with penicillin allergy 6
• Macrolides can be used but resistance rates are increasing 2

Pregnant Patients

• Cephalexin is considered a safe alternative for pregnant patients 2, 6

Outbreak Settings

• During outbreaks of poststreptococcal glomerulonephritis, systemic antimicrobials should be used to eliminate nephritogenic strains of S. pyogenes from the community 1, 2

Infection Control Measures

• Keep lesions covered with clean, dry bandages to prevent spread 2, 6
• Maintain strict hand hygiene with regular handwashing 2, 6
• Avoid sharing personal items that contact the skin (towels, clothing, bedding) 2, 6