Is mupirocin (topical antibiotic) and doxycycline (systemic antibiotic) an appropriate treatment for a patient with mild cellulitis from a burn, considering potential Methicillin-resistant Staphylococcus aureus (MRSA) coverage and possible impaired renal function?

Mupirocin and Doxycycline for Mild Burn-Related Cellulitis: Inappropriate Regimen

This combination is inappropriate for treating cellulitis from a burn—mupirocin is indicated only for superficial skin infections like impetigo, not cellulitis, and doxycycline requires combination with a beta-lactam for adequate streptococcal coverage. 1

Why This Regimen Fails

Mupirocin's Limited Role

• Mupirocin is FDA-approved for impetigo and secondarily infected minor skin lesions (eczema, ulcers, lacerations), not cellulitis 2
• The drug demonstrates no measurable systemic absorption (<1.1 ng/mL) after topical application, making it ineffective for deeper soft tissue infections like cellulitis 2
• While mupirocin shows excellent activity against MRSA in burn wounds in research settings 3, 4, 5, these studies examined burn wound colonization/superficial infection, not established cellulitis with deeper tissue involvement
• The Infectious Diseases Society of America recommends mupirocin only for minor skin infections such as impetigo and secondarily infected skin lesions, not cellulitis 1

Doxycycline Monotherapy is Inadequate

• The Infectious Diseases Society of America explicitly states that doxycycline must be combined with a beta-lactam when treating typical nonpurulent cellulitis, as tetracyclines lack reliable activity against beta-hemolytic streptococci 1
• Streptococci (especially Streptococcus pyogenes) are the primary pathogens in typical cellulitis, and doxycycline monotherapy provides inadequate coverage 1
• Doxycycline alone is appropriate only for purulent cellulitis requiring MRSA coverage, and even then must be combined with a beta-lactam 1

Correct Treatment Algorithm for Mild Burn-Related Cellulitis

First-Line Therapy

• Beta-lactam monotherapy is the standard of care for typical uncomplicated cellulitis, with 96% success rates 1
• Recommended oral agents include:
  • Cephalexin 500 mg every 6 hours 1
  • Dicloxacillin 250-500 mg every 6 hours 1
  • Amoxicillin-clavulanate 875/125 mg twice daily 1
• Treatment duration: 5 days if clinical improvement occurs, extending only if symptoms persist 1

When to Add MRSA Coverage

Add MRSA-active antibiotics only when specific risk factors are present 1:

• Penetrating trauma (burn wounds may qualify depending on depth/mechanism)
• Purulent drainage or exudate
• Injection drug use
• Known MRSA colonization
• Systemic inflammatory response syndrome (SIRS)

MRSA-Active Regimens (if indicated)

• Clindamycin 300-450 mg every 6 hours provides single-agent coverage for both streptococci and MRSA (use only if local resistance <10%) 1
• Alternative: Doxycycline 100 mg twice daily PLUS a beta-lactam (cephalexin or dicloxacillin) 1
• Alternative: Trimethoprim-sulfamethoxazole 1-2 double-strength tablets twice daily PLUS a beta-lactam 1

Critical Pitfalls to Avoid

• Do not use topical antibiotics like mupirocin for cellulitis—they lack systemic penetration needed for deeper tissue infections 2
• Never use doxycycline as monotherapy for cellulitis—streptococcal coverage will be inadequate 1
• Do not reflexively add MRSA coverage for typical nonpurulent cellulitis without specific risk factors—this represents overtreatment 1
• For burn-related cellulitis specifically, assess whether the burn created a portal for penetrating trauma, which would warrant MRSA coverage 1

Adjunctive Measures

• Elevate the affected extremity above heart level for at least 30 minutes three times daily to promote drainage 1
• Examine interdigital toe spaces for tinea pedis and treat if present to reduce recurrence 1
• Address predisposing conditions including edema, venous insufficiency, and lymphedema 1