What is the first-line treatment for impetigo in an adult patient?

First-Line Treatment for Impetigo in Adults

Mupirocin 2% ointment applied three times daily for 5-7 days is the first-line treatment for localized impetigo in adults. 1, 2, 3

Topical Therapy for Limited Disease

• Mupirocin 2% ointment is the gold standard topical agent with clinical efficacy rates of 71-93% in controlled trials, providing effective coverage against both S. aureus and S. pyogenes. 2

• Apply mupirocin 2% ointment to affected areas three times daily for 5-7 days, keeping lesions covered with clean, dry bandages when possible to prevent spread. 1

• Retapamulin 1% ointment applied twice daily for 5 days is an effective alternative if mupirocin is unavailable or has failed. 1, 2, 4

• Avoid bacitracin and neomycin as they are considerably less effective and should not be used. 2

When to Escalate to Oral Antibiotics

Switch to oral antibiotics if:

• No improvement after 48-72 hours of topical therapy 1, 2, 3
• The impetigo is extensive or involves multiple sites 3
• Systemic symptoms develop (fever, malaise, lymphadenopathy) 2
• Topical therapy is impractical 3

Oral Antibiotic Selection for Adults

For presumed Methicillin-Susceptible S. aureus (MSSA):

• Dicloxacillin 250 mg four times daily 2, 3
• Cephalexin 250-500 mg four times daily 2, 3

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

• Clindamycin 300-450 mg three times daily 2, 3
• Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets twice daily 2
• Doxycycline (appropriate for adults) 3

Critical Pitfalls to Avoid

• Never use penicillin alone as it lacks adequate coverage against S. aureus. 2, 3

• Avoid rifampin as monotherapy or adjunctive therapy for skin infections. 2

• Re-evaluate after 48-72 hours if no improvement is observed, and consider obtaining cultures if treatment fails or MRSA is suspected. 1, 3

Treatment Duration

• Topical treatment: 5-7 days 1, 3
• Oral antibiotics: 5-10 days 3