What is the treatment for cellulitis of the lower extremities?

Treatment of Cellulitis of Lower Extremities

For typical cases of cellulitis without systemic signs of infection, an antimicrobial agent active against streptococci such as penicillin, dicloxacillin, cephalexin, clindamycin, or erythromycin should be prescribed for 5 days, with treatment extended if infection has not improved within this time period. 1, 2

Antibiotic Selection Algorithm

Mild Cellulitis (No Systemic Signs)

• First-line therapy: Antibiotics targeting streptococci 1, 2
  • Penicillin VK 250-500 mg every 6 hours orally
  • Dicloxacillin 500 mg four times daily
  • Cephalexin 500 mg four times daily
  • Clindamycin 300-450 mg three times daily
  • Erythromycin 400 mg four times daily

Moderate Cellulitis (With Systemic Signs)

• Include coverage for both streptococci and MSSA 1, 2
  • Cefazolin 1 g every 8 hours IV
  • Oxacillin or nafcillin 2 g every 6 hours IV
  • Clindamycin 600-900 mg every 8 hours IV (if penicillin allergic)

Severe Cellulitis (SIRS, Penetrating Trauma, MRSA Risk)

• Use antimicrobials effective against both MRSA and streptococci 1
  • Vancomycin 15-20 mg/kg every 12 hours IV
  • Linezolid 600 mg every 12 hours IV or orally
  • Daptomycin 4 mg/kg daily IV
  • Telavancin as appropriate dosing

When to Consider MRSA Coverage

• Purulent drainage
• History of MRSA infection
• Injection drug use
• Penetrating trauma
• Failure of initial β-lactam therapy
• High local MRSA prevalence 2
  • Options include:
    • Trimethoprim-sulfamethoxazole 1-2 DS tablets twice daily
    • Doxycycline 100 mg twice daily
    • Clindamycin 300-450 mg three times daily

Treatment Duration

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

Supportive Care Measures

1. Elevate the affected area to reduce swelling and promote healing 1, 2
2. Treat predisposing factors:
   • Edema
   • Obesity
   • Underlying cutaneous disorders
   • Venous insufficiency
   • Lymphedema 1, 2
3. Examine interdigital toe spaces and treat fissuring, scaling, or maceration to eradicate colonization with pathogens 1, 2
4. For diabetic patients: Metabolic stabilization (fluid/electrolyte balance, glycemic control) 2

Adjunctive Therapy

• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adult patients 1, 2
  • Contraindications: Age <18 years, diabetes, pregnancy, necrotizing infections, immunocompromised state 2
  • Benefits: Can shorten healing time by approximately 1 day and reduce hospital stay 2

Patient Disposition

• Outpatient treatment for patients without:

  • SIRS
  • Altered mental status
  • Hemodynamic instability 1, 2

• Hospitalization recommended for:

  • Concern for deeper or necrotizing infection
  • Poor adherence to therapy
  • Severely immunocompromised patients
  • Failing outpatient treatment
  • Extensive or rapidly progressing infection
  • Significant metabolic derangements 1, 2

Prevention of Recurrence

1. Identify and treat predisposing conditions:

   • Edema
   • Obesity
   • Eczema
   • Venous insufficiency
   • Toe web abnormalities
   • Tinea pedis 1, 2

2. Consider prophylactic antibiotics for patients with 3-4 episodes per year:

   • Oral penicillin or erythromycin twice daily for 4-52 weeks
   • Intramuscular benzathine penicillin every 2-4 weeks 1, 3
   • Continue prophylaxis as long as predisposing factors persist

Common Pitfalls to Avoid

1. Misdiagnosis: Venous insufficiency, eczema, deep vein thrombosis, and gout are frequently mistaken for cellulitis 4, 5
2. Overuse of broad-spectrum antibiotics: Studies show no benefit of broad-spectrum over narrow-spectrum antibiotics for uncomplicated cellulitis 6
3. Inadequate evaluation of toe web spaces: Failure to identify and treat interdigital infections can lead to recurrence 1, 2
4. Failure to address underlying conditions: Not treating predisposing factors leads to higher recurrence rates 1, 2, 3
5. Unnecessary MRSA coverage for non-purulent cellulitis in the absence of risk factors 5