What is the treatment for impetigo?

Treatment of Impetigo

For localized impetigo, start with topical mupirocin 2% ointment applied three times daily for 5-7 days; switch to oral antibiotics (dicloxacillin or cephalexin for MSSA, clindamycin or trimethoprim-sulfamethoxazole for MRSA) if the disease is extensive, involves multiple sites, fails topical therapy after 3-5 days, or presents with systemic symptoms. 1, 2

First-Line Topical Treatment

• Mupirocin 2% ointment applied three times daily is the most effective topical agent for impetigo caused by S. aureus and S. pyogenes, with clinical efficacy rates of 71-93% compared to 35% for placebo 1, 3
• Treatment duration should be 5-7 days for topical therapy 1, 2
• Retapamulin 1% ointment applied twice daily for 5 days is an effective alternative for limited disease 2
• Avoid bacitracin and neomycin as they are considerably less effective and should not be used 1
• Do not use topical clindamycin cream (the acne formulation) as it lacks FDA indication for impetigo and has insufficient systemic absorption (only 4% bioavailability) to treat bacterial skin infections 1

Indications for Oral Antibiotics

Switch to oral therapy when any of the following are present:

• Extensive disease or involvement of multiple sites 1, 2
• Lesions on the face, eyelid, or mouth 1
• Failure to respond to topical therapy after 3-5 days 1, 2
• Topical therapy is impractical (e.g., scalp involvement with hair) 2
• Systemic symptoms present 1, 2
• Need to limit spread to others in high-transmission settings 1

Oral Antibiotic Selection

For Methicillin-Susceptible S. aureus (MSSA):

• Dicloxacillin 250 mg four times daily for adults 1, 2
• Cephalexin 250-500 mg four times daily for adults 1, 2
• Duration: 5-10 days 1, 2

For Methicillin-Resistant S. aureus (MRSA) - suspected or confirmed:

• Clindamycin 300-450 mg three times daily for adults (oral formulation, not topical cream) 1, 2
• Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily for adults 1, 2
• Doxycycline (avoid in children under 8 years) 2

Critical Pitfall:

Penicillin alone is not effective for impetigo as it lacks adequate coverage against S. aureus 1, 2

When to Obtain Cultures

Obtain cultures from lesions (vesicle fluid, pus, or erosions) in these situations:

• Treatment failure with appropriate therapy 1, 2
• MRSA is suspected 1, 2
• Recurrent infections 1, 2

Special Population Considerations

• Avoid tetracyclines (doxycycline, minocycline) in children under 8 years of age 1, 2
• Cephalexin is a safe alternative for pregnant patients 1
• Oral antibiotic dosing should be adjusted by weight for children 2
• Clindamycin is the preferred alternative for penicillin-allergic patients 1

Prevention of Spread

• Keep lesions covered with clean, dry bandages 1, 2
• Maintain good personal hygiene with regular handwashing 1
• Avoid sharing personal items that contact the skin 1

Follow-Up and Re-evaluation

• Re-evaluate if no improvement after 48-72 hours of appropriate therapy 2
• If impetigo is not responding to appropriate therapy, consider alternative diagnoses 2
• Adjust therapy based on culture susceptibility results if obtained 2