What is the recommended treatment for uncomplicated cellulitis?

Treatment of Uncomplicated Cellulitis

First-Line Treatment Recommendations

For uncomplicated cellulitis, the recommended first-line treatment is a 5-6 day course of antibiotics targeting Streptococcus and methicillin-sensitive Staphylococcus aureus (MSSA), with options including cephalexin (500 mg 3-4 times daily), clindamycin (300-450 mg three times daily), or amoxicillin-clavulanate (875/125 mg twice daily). 1

The primary causative organisms in cellulitis are β-hemolytic Streptococcus and Staphylococcus aureus, which should guide empiric antibiotic selection 2. Treatment should be directed at these pathogens unless specific risk factors for MRSA are present.

Antibiotic Selection Algorithm

1. First-line options (choose one):

   • Cephalexin: 500 mg orally 3-4 times daily for 5-6 days
   • Clindamycin: 300-450 mg orally three times daily for 5-6 days
   • Amoxicillin-clavulanate: 875/125 mg orally twice daily for 5-6 days

2. When to consider MRSA coverage:

   • Prior MRSA infection
   • Injection drug use
   • Recent hospitalization
   • Athletes
   • Children
   • Men who have sex with men
   • Prisoners
   • Military recruits
   • Residents of long-term care facilities 1, 2

3. MRSA coverage options:

   • TMP-SMX: 1-2 double-strength tablets twice daily
   • Doxycycline: 100 mg twice daily (not for children under 8 years)
   • Linezolid: 600 mg twice daily (expensive, risk of myelosuppression)
   • Daptomycin: 4 mg/kg IV once daily (for severe cases) 1

Treatment Duration

Strong evidence supports a short-course (5-6 days) antibiotic regimen for uncomplicated cellulitis. A randomized controlled trial demonstrated that 5 days of antibiotic therapy was as effective as 10 days, with a 98% success rate in both groups 3. This is consistent with guideline recommendations for 5-6 days of treatment for uncomplicated skin infections 1.

Assessment and Follow-up

• Clinical improvement should be assessed within 72 hours of starting therapy
• If no improvement is seen within this timeframe, reevaluation is necessary 1
• Consider alternative diagnoses if not improving (venous insufficiency, eczema, deep vein thrombosis, gout) 4
• Consider culture-guided therapy if initial treatment fails 5

Special Considerations

• Surgical drainage is essential if an abscess develops
• Blood cultures should be obtained in patients with severe infection or systemic symptoms
• Consider hospitalization if:
  • Concern for deeper or necrotizing infection
  • Poor adherence to therapy
  • Severely immunocompromised patient
  • Outpatient treatment is failing 1

Prevention of Recurrence

Addressing predisposing factors is crucial to minimize risk of recurrence 2:

• Maintain good hand hygiene
• Keep skin clean and dry
• Promptly treat minor skin breaks
• Daily change of socks and careful drying between toes 1

Common Pitfalls to Avoid

1. Inadequate MRSA coverage when risk factors are present
2. Overtreatment with unnecessarily prolonged courses (>5-6 days) for uncomplicated cases
3. Misdiagnosis of conditions that mimic cellulitis (venous stasis, contact dermatitis, etc.)
4. Failure to consider unusual pathogens in cases that don't respond to initial therapy 5
5. Missing deeper infections that require surgical intervention

Remember that cellulitis is a clinical diagnosis based primarily on history and physical examination, with no reliable diagnostic tests 2. The key features include expanding erythema, warmth, tenderness, and swelling of the affected area.