What is the first-line treatment for impetigo?

First-Line Treatment for Impetigo

For limited impetigo, topical mupirocin 2% ointment applied twice to three times daily for 5-7 days is the first-line treatment; for extensive disease, systemic symptoms, or lesions on the face/mouth, use oral cephalexin or dicloxacillin for 7 days. 1, 2, 3

Treatment Algorithm Based on Disease Extent

Limited Disease (Few Lesions)

• Topical mupirocin 2% ointment is the most effective first-line agent, applied twice to three times daily for 5-7 days 1, 3
• Topical mupirocin achieves cure rates 6-fold higher than placebo and is superior to oral antibiotics for limited disease 2, 4
• Retapamulin 1% ointment twice daily for 5 days is an alternative for patients aged 9 months or older (covering up to 100 cm² in adults or 2% total body surface area in children) 2
• Avoid bacitracin and neomycin as they are considerably less effective 1

Extensive Disease or Indications for Oral Therapy

Switch to oral antibiotics when: 1, 2

• Multiple or extensive lesions are present
• No improvement after 3-5 days of topical therapy
• Systemic symptoms develop
• Lesions involve the face, eyelid, or mouth
• Need to limit spread during outbreaks

Oral Antibiotic Selection

For Presumed Methicillin-Susceptible S. aureus (MSSA)

• Cephalexin: Adults 250-500 mg four times daily; Children 25-50 mg/kg/day divided into 4 doses for 7 days 2
• Dicloxacillin: Adults 250 mg four times daily; Children 25-50 mg/kg/day divided into 4 doses for 7 days 1, 2
• Co-amoxiclav (amoxicillin-clavulanate) is an acceptable alternative when dicloxacillin or cephalexin are not suitable 2

For Suspected or Confirmed MRSA

In areas with high MRSA prevalence, use empiric MRSA coverage: 1, 2

• Clindamycin: Adults 300-450 mg three to four times daily; Children 20-30 mg/kg/day divided into 3 doses for 7 days
• Trimethoprim-sulfamethoxazole: Adults 1-2 double-strength tablets twice daily; Children 8-12 mg/kg/day (trimethoprim component) divided into 2 doses for 7 days
• Doxycycline: Only for children over 8 years old at 2-4 mg/kg/day divided into 2 doses for 7 days (avoid in younger children due to dental staining risk) 1, 2

Critical Treatment Duration

• Topical antibiotics: 5-7 days 1, 2
• Oral antibiotics: 7 days (not the shorter 5-day course) 1, 2

Antibiotics to Avoid

• Penicillin alone lacks adequate coverage against S. aureus and is seldom effective; use only when cultures confirm streptococci alone 1, 2
• Amoxicillin alone should not be used as it lacks adequate S. aureus coverage 2
• Cefdinir should not be used when MRSA is suspected, documented, or confirmed 2
• Topical clindamycin cream (formulated for acne) lacks FDA indication for impetigo and has insufficient bioavailability for bacterial skin infections 1

Penicillin Allergy Management

• Use cephalexin (first-generation cephalosporin) except in patients with type 1 hypersensitivity reactions (anaphylaxis/hives) 1, 2
• For true penicillin allergy with immediate hypersensitivity, use clindamycin or macrolides (though erythromycin resistance rates are rising) 2, 5

Special Populations

Children

• Avoid tetracyclines (doxycycline) in children under 8 years due to permanent dental staining risk 1, 2
• Topical mupirocin is particularly effective and well-tolerated in pediatric patients 2, 6

Pregnant Patients

• Cephalexin is considered a safe alternative 1

Immunocompromised Patients

• Use a lower threshold for oral antibiotics 1
• Monitor closely for treatment failure or deeper infection 1
• Consider longer treatment duration based on clinical response 1
• Cultures may be indicated even for limited disease 1

Infection Control and Prevention

• Keep lesions covered with clean, dry bandages 1, 2
• Maintain good personal hygiene with regular handwashing 1, 2
• Avoid sharing personal items that contact the skin (towels, equipment) 1, 2
• Athletes should be excluded from participation until 24 hours after initiation of effective antimicrobial therapy, with lesions covered 1

When to Reassess

If no improvement occurs by 3-5 days of appropriate therapy, consider: 1

• MRSA infection requiring alternative antibiotics
• Deeper or more complex infection than initially estimated
• Non-compliance with therapy
• Antibiotic resistance (obtain cultures for recurrent infections, treatment failure, or suspected MRSA) 1

Outbreak Management

• Use systemic antimicrobials during outbreaks of poststreptococcal glomerulonephritis to eliminate nephritogenic strains of S. pyogenes from the community 1, 2
• Consider decolonization strategies using topical nasal mupirocin therapy for S. aureus carriers 1
• Involve public health authorities in outbreak management 1

Common Pitfalls to Avoid

• Do not use topical disinfectants as primary therapy—there is little evidence they improve outcomes and they are inferior to antibiotics 1, 4, 7
• Do not prescribe oral antibiotics for limited disease when topical therapy is appropriate and more effective 2
• Side-effects are more common with oral antibiotics (primarily gastrointestinal) compared to topical treatment 4