What is the treatment for leg cellulitis?

Treatment for Leg Cellulitis

First-line treatment for leg cellulitis is an antibiotic active against streptococci, such as penicillin, amoxicillin, dicloxacillin, cephalexin, or clindamycin, for 5 days if clinical improvement occurs. 1, 2

Antibiotic Selection

Mild Cellulitis (Outpatient)

• Oral cephalexin 500 mg four times daily 1
• Oral dicloxacillin 500 mg four times daily 1
• Oral clindamycin 300-450 mg three to four times daily (for penicillin-allergic patients) 1, 2
• Oral penicillin or amoxicillin are also appropriate options 2, 3

Moderate to Severe Cellulitis (Inpatient)

• IV cefazolin 1 g every 8 hours 1, 2
• IV nafcillin/oxacillin 1-2 g every 4-6 hours 1, 2
• IV penicillin G 2-4 million units every 4-6 hours 1
• IV vancomycin 15 mg/kg every 12 hours (for penicillin-allergic patients) 2

Duration of Therapy

• 5 days of antibiotic therapy is sufficient for uncomplicated cellulitis if clinical improvement occurs 2, 1
• Treatment should be extended if the infection has not improved within this time period 2, 1

MRSA Considerations

• MRSA is an unusual cause of typical cellulitis, with β-lactam therapy successful in 96% of patients 2, 1

• Consider MRSA coverage in cellulitis associated with:

  • Penetrating trauma, especially from illicit drug use 2, 1
  • Purulent drainage 2, 1
  • Concurrent evidence of MRSA infection elsewhere 2, 1
  • History of MRSA colonization 1
  • Presence of systemic inflammatory response syndrome 1

• MRSA coverage options:

  • Oral: trimethoprim-sulfamethoxazole, doxycycline, or clindamycin 2, 1
  • IV: vancomycin, daptomycin, linezolid, or telavancin 2, 1

Adjunctive Measures

• Elevation of the affected area to promote gravity drainage of edema and inflammatory substances 2, 1
• Treatment of predisposing factors such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 2, 1
• Careful examination of interdigital toe spaces to identify and treat fissuring, scaling, or maceration 2, 1
• Systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) could be considered in non-diabetic adult patients 2, 1

Hospitalization Criteria

• Presence of SIRS, altered mental status, or hemodynamic instability 2, 1
• Concern for deeper or necrotizing infection 2, 1
• Poor adherence to therapy 2, 1
• Infection in a severely immunocompromised patient 2, 1
• Outpatient treatment failure 2, 1

Prevention of Recurrent Cellulitis

• Identify and treat predisposing conditions such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 2, 1
• For patients with 3-4 episodes per year despite addressing predisposing factors, consider prophylactic antibiotics:
  • Oral penicillin or erythromycin twice daily for 4-52 weeks 2, 1
  • Intramuscular benzathine penicillin every 2-4 weeks 2, 1, 4
• Prophylaxis is most effective in patients without predisposing factors 4

Common Pitfalls

• Failing to differentiate cellulitis from pseudocellulitis conditions like venous stasis dermatitis, contact dermatitis, or lymphedema 5
• Unnecessarily prescribing MRSA coverage for typical non-purulent cellulitis 2, 5
• Using antibiotics for longer than necessary (5 days is sufficient if improvement occurs) 2, 1
• Not addressing underlying predisposing factors, leading to recurrence 2, 1, 6
• Not elevating the affected limb, which slows resolution 2, 1