What is the recommended treatment for cellulitis of the lower extremities?

Treatment of Cellulitis of the Lower Extremities

For uncomplicated cellulitis of the lower extremities, a 5-day course of antibiotics targeting streptococci is the recommended first-line treatment, with extension if the infection has not improved within this time period. 1

Antibiotic Selection

First-Line Treatment

• For mild, typical cellulitis without systemic signs:
  • Antibiotics active against streptococci 2, 1:
    • Penicillin VK 250-500 mg every 6 hours orally
    • Dicloxacillin
    • Cephalexin
    • Clindamycin
    • Erythromycin 400 mg 4 times/day orally

For Moderate to Severe Infections

• With systemic signs of infection:

  • Consider coverage for both streptococci and MSSA 2

• For severe infections or high-risk situations:

  • Vancomycin or another antimicrobial effective against both MRSA and streptococci when 2, 1:
    • Associated with penetrating trauma
    • Evidence of MRSA infection elsewhere
    • Nasal colonization with MRSA
    • Injection drug use
    • Systemic inflammatory response syndrome (SIRS)

• For severely compromised patients:

  • Vancomycin plus either piperacillin-tazobactam or imipenem/meropenem 2

MRSA Coverage Considerations

• Add MRSA coverage if 1:

  • Purulent drainage
  • History of MRSA infection
  • Injection drug use
  • Penetrating trauma
  • Failure of initial β-lactam therapy
  • High local prevalence of MRSA

• MRSA treatment options 1:

  • Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 DS tablets twice daily
  • Doxycycline 100mg twice daily
  • Clindamycin 300-450mg three times daily

Duration of Treatment

• Standard duration: 5 days 2, 1
• Extend treatment if:
  • Infection has not improved within 5 days
  • Immunocompromised patients (10-14 days)
  • Diabetic patients (10-14 days)
  • Severe infections (10-14 days)
  • Slow clinical response (10-14 days)

Adjunctive Measures

1. Elevation of the affected area 2, 1

2. Treatment of predisposing factors 2, 1:

   • Edema
   • Obesity
   • Underlying cutaneous disorders
   • Venous insufficiency
   • Lymphedema

3. Careful examination of interdigital toe spaces 2

   • Treating fissuring, scaling, or maceration may reduce recurrence

4. Consider systemic corticosteroids in non-diabetic adult patients 2, 1

   • Prednisone 40 mg daily for 7 days
   • Can shorten healing time by approximately 1 day
   • Avoid in patients under 18, diabetic patients, pregnant women, patients with necrotizing infections, and immunocompromised patients

Treatment Setting

• Outpatient treatment for patients without 2, 1:

  • SIRS
  • Altered mental status
  • Hemodynamic instability

• Hospitalization recommended for 2, 1:

  • Concern for deeper or necrotizing infection
  • Poor adherence to therapy
  • Severely immunocompromised patients
  • Failing outpatient treatment
  • Extensive or rapidly progressing infection
  • Significant metabolic derangements

Prevention of Recurrence

• Identify and treat predisposing conditions 2, 1:

  • Edema
  • Obesity
  • Eczema
  • Venous insufficiency
  • Toe web abnormalities
  • Tinea pedis

• For frequent recurrences (3-4 episodes per year) 2, 1:

  • Consider prophylactic antibiotics:
    • Oral penicillin or erythromycin twice daily for 4-52 weeks
    • Intramuscular benzathine penicillin every 2-4 weeks
  • Continue as long as predisposing factors persist

Important Clinical Considerations

• Clinical improvement should be evident within 48-72 hours; if not, reassess diagnosis 1
• Avoid broad-spectrum antibiotics for uncomplicated cellulitis as they show no benefit over narrow-spectrum options 3
• In areas with high MRSA prevalence, antibiotics with activity against community-associated MRSA (TMP-SMX, clindamycin) may be preferred for empiric therapy 4
• Be vigilant about pseudocellulitis - conditions like venous stasis dermatitis, contact dermatitis, eczema, and lymphedema are frequently mistaken for cellulitis 5