What is the initial treatment approach for a patient with a mild to moderate skin infection, such as impetigo or folliculitis, considering their medical history and potential allergies?

Treatment for Mild to Moderate Skin Infections

For localized impetigo with limited lesions, topical mupirocin 2% ointment applied three times daily is the first-line treatment, while patients with numerous lesions or folliculitis should receive oral antibiotics effective against both S. aureus and S. pyogenes, such as cephalexin, with consideration for local MRSA prevalence. 1

Initial Assessment and Treatment Selection

The treatment approach depends on three key factors: extent of infection, specific diagnosis, and local resistance patterns 1:

For Impetigo (Honey-Crusted Lesions)

Topical therapy:

• Mupirocin 2% ointment is the best topical agent, applied three times daily for 8-12 days 1, 2
• Clinical efficacy of 71-93% in clinical trials, significantly superior to placebo (35%) and comparable to oral erythromycin 2
• Use topical therapy when lesions are few in number and not located on face, eyelid, or mouth 1
• Note that mupirocin resistance has been described, though it remains highly effective 1, 3

Oral therapy indications:

• Numerous lesions, facial involvement, or failure of topical treatment 1
• Oral antibiotics must cover both S. aureus and S. pyogenes 1
• Options include: synthetic penicillin, first-generation cephalosporins (e.g., cephalexin), or second-generation cephalosporins 1
• Alternative agents: macrolides or clindamycin, though 50% of MRSA strains have clindamycin resistance 1

For Folliculitis

Oral antibiotic therapy is typically required:

• Cephalexin, TMP/SMX, or doxycycline based on local susceptibility patterns for 10 days 1
• Consider local MRSA prevalence when selecting empiric therapy 1

MRSA Considerations

Critical decision point: In areas with high community-acquired MRSA prevalence, adjust empiric therapy accordingly 1:

• If MRSA is suspected or prevalent locally, consider:

  • TMP/SMX (trimethoprim-sulfamethoxazole) 1
  • Doxycycline or minocycline (though 21% treatment failure rates reported) 1
  • Clindamycin (if susceptibility confirmed, as 50% of MRSA has resistance) 1

• Mandatory 24-48 hour follow-up when using TMP/SMX or tetracyclines to verify clinical response 1

• Progression despite antibiotics suggests resistant organisms or deeper infection than initially recognized 1

Treatment Duration and Monitoring

• Standard duration: 10 days for most oral regimens 1
• Topical mupirocin: 8-12 days 2
• Re-evaluate within 24-48 hours if empiric therapy includes agents with known MRSA treatment failures 1

Important Caveats

Allergy considerations:

• For penicillin allergy: macrolides (erythromycin, azithromycin) or clindamycin 1
• Be aware that macrolide resistance in S. pyogenes has increased to 8-9%, though 100% remain penicillin-susceptible 1

When to escalate care:

• Systemic signs of infection (fever, tachycardia) 1
• Progression despite appropriate antibiotics 1
• Immunocompromised patients 1
• Deep tissue involvement or severe cellulitis 1

Avoid common pitfalls:

• Do not use bacitracin or neomycin for impetigo—they are considerably less effective than mupirocin 1
• Do not use mupirocin as monotherapy for moderate-to-severe or deep tissue infections 3
• Do not assume clindamycin will cover MRSA without susceptibility testing 1