What is the recommended treatment for cellulitis?

Treatment of Cellulitis

For typical cases of cellulitis without systemic signs of infection, a 5-day course of antibiotics active against streptococci is the recommended treatment. 1

Antibiotic Selection Algorithm

Mild Cellulitis (without systemic signs)

• First-line treatment: Antibiotics active against streptococci 1
  • Penicillin
  • Amoxicillin
  • Dicloxacillin
  • Cephalexin (500 mg every 6 hours orally)
  • Clindamycin (for penicillin-allergic patients)

Moderate Cellulitis (with systemic signs)

• Treatment: Systemic antibiotics with coverage for streptococci and possibly MSSA 1
  • Consider hospitalization if patient has poor adherence, is immunocompromised, or outpatient treatment is failing

Severe Cellulitis (with SIRS or high-risk factors)

• Treatment: Vancomycin or another antimicrobial effective against both MRSA and streptococci 1
• High-risk factors for MRSA:
  • Penetrating trauma
  • Evidence of MRSA infection elsewhere
  • Nasal colonization with MRSA
  • Injection drug use
  • Systemic inflammatory response syndrome (SIRS)

Severely Compromised Patients

• Treatment: Broad-spectrum coverage with vancomycin plus either piperacillin-tazobactam or imipenem/meropenem 1

Duration of Treatment

• Standard duration: 5 days 1
• Extend treatment if infection has not improved within this time period 1

Adjunctive Measures

1. Elevation of the affected area to promote drainage of edema and inflammatory substances 1
2. Treatment of predisposing factors such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 1
3. For lower-extremity cellulitis: Examine interdigital toe spaces and treat fissuring, scaling, or maceration to reduce recurrence 1
4. Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adult patients to hasten resolution 1, 2

Hospitalization Criteria

Hospitalization is recommended if:

• Concern for deeper or necrotizing infection
• Poor adherence to therapy
• Severely immunocompromised patient
• Outpatient treatment is failing
• SIRS, altered mental status, or hemodynamic instability 1

Management of Recurrent Cellulitis

For patients with 3-4 episodes per year despite treatment of predisposing factors:

• Prophylactic antibiotics: Oral penicillin or erythromycin twice daily for 4-52 weeks, or intramuscular benzathine penicillin every 2-4 weeks 1
• Decolonization regimen for recurrent S. aureus infections:
  • Intranasal mupirocin twice daily for 5 days
  • Daily chlorhexidine washes
  • Daily decontamination of personal items (towels, sheets, clothes) 1

Important Caveats and Pitfalls

1. MRSA coverage is not routinely needed for typical non-purulent cellulitis 3, 4

   • A study showed that adding trimethoprim-sulfamethoxazole to cephalexin did not improve outcomes in uncomplicated cellulitis 4

2. Cultures are not routinely recommended for typical cases but should be considered in:

   • Patients with malignancy on chemotherapy
   • Neutropenia
   • Severe cell-mediated immunodeficiency
   • Immersion injuries
   • Animal bites 1

3. Diagnostic challenges: Cellulitis can be difficult to diagnose due to mimickers such as:

   • Venous stasis dermatitis
   • Contact dermatitis
   • Eczema
   • Lymphedema 3

4. Treatment failure should prompt consideration of:

   • Resistant organisms
   • Secondary conditions mimicking cellulitis
   • Underlying complicating conditions (immunosuppression, chronic liver/kidney disease) 5

By following this evidence-based approach to cellulitis treatment, focusing on appropriate antibiotic selection, duration, and adjunctive measures, clinicians can effectively manage this common infection while minimizing unnecessary broad-spectrum antibiotic use.