What is the recommended treatment for a patient with impetigo, considering severity, potential allergies, and immunocompromised status?

Treatment of Impetigo

For limited impetigo, topical mupirocin 2% ointment applied three times daily for 5-7 days is the first-line treatment, while extensive disease, systemic symptoms, or lesions on the face/mouth require oral antibiotics such as cephalexin or dicloxacillin for 7 days. 1, 2

Initial Assessment and Treatment Selection

The choice between topical and oral therapy depends on disease extent and location:

Topical therapy is appropriate when:

• Lesions are limited (up to 100 cm² in adults or 2% body surface area in children) 3
• No systemic symptoms present 2
• Lesions are not on face, eyelid, or mouth 2
• Patient can comply with three-times-daily application 1

Oral antibiotics are required when:

• Impetigo is extensive or involves multiple sites 2
• Topical therapy fails after 3-5 days 2
• Systemic symptoms are present 1
• Lesions involve face, eyelid, or mouth 2
• Need to limit spread to others 2

Topical Antibiotic Options

Mupirocin 2% ointment is the most effective topical agent for impetigo caused by S. aureus and S. pyogenes, applied three times daily for 5-7 days. 1, 2 Retapamulin ointment is an FDA-approved alternative applied twice daily for 5 days in patients ≥9 months old. 3

Important caveat: Bacitracin and neomycin are considerably less effective and should not be used. 2 Clindamycin cream lacks FDA indication for impetigo and should not be used topically for this condition. 2

Oral Antibiotic Selection

The choice of oral antibiotic depends on local MRSA prevalence and patient allergies:

For presumed methicillin-susceptible S. aureus (MSSA):

• Dicloxacillin 250 mg four times daily for adults 2
• Cephalexin 250-500 mg four times daily for adults 2
• Duration: 7 days 1

When MRSA is suspected or confirmed:

• Clindamycin 300-450 mg three times daily for adults 2
• Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily for adults 2
• Duration: 7 days 1

Critical pitfall: Penicillin alone is not effective for impetigo as it lacks adequate coverage against S. aureus. 2 Amoxicillin without clavulanate is similarly inadequate. 4

Special Populations and Allergy Considerations

For penicillin-allergic patients:

• Clindamycin is the preferred alternative 2
• Avoid cephalosporins if type 1 hypersensitivity (anaphylaxis/hives) to β-lactams 1

Pediatric considerations:

• Avoid tetracyclines (doxycycline, minocycline) in children under 8 years 2
• Mupirocin and retapamulin are safe topical options for children ≥9 months 3

Pregnancy:

• Cephalexin is a safe alternative 2

Immunocompromised Patients

Immunocompromised patients require more aggressive management:

• Lower threshold for oral antibiotics 1
• Consider obtaining cultures before treatment 2
• Monitor closely for treatment failure or deeper infection 1
• May require longer treatment duration based on clinical response 1

Culture Indications

Obtain Gram stain and culture when:

• Treatment failure occurs 2
• MRSA is suspected 2
• Recurrent infections 2
• Immunocompromised host 1

Cultures are not routinely necessary for typical cases of limited impetigo. 1

Prevention of Spread

• Keep lesions covered with clean, dry bandages 2
• Maintain good personal hygiene with regular handwashing 2
• Avoid sharing personal items that contact the skin 2

Treatment During Outbreaks

Systemic antimicrobials should be used during outbreaks of poststreptococcal glomerulonephritis to help eliminate nephritogenic strains of S. pyogenes from the community. 1 This represents a public health indication beyond individual patient treatment.

Monitoring and Follow-up

Clinical improvement should be evident within 3-5 days of appropriate therapy. 2, 4 If no improvement occurs by this timeframe, reassess for:

• MRSA infection requiring alternative antibiotics 1
• Deeper or more complex infection than initially estimated 1
• Non-compliance with therapy 1
• Antibiotic resistance 1