What is the recommended treatment for cellulitis?

Treatment for Cellulitis

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

Antibiotic Selection Algorithm

Mild Uncomplicated Cellulitis (outpatient treatment)

• First-line therapy: Antibiotics active against streptococci
  • Penicillin (250-500 mg every 6 hours orally)
  • Amoxicillin (500 mg three times daily)
  • Cephalexin (500 mg every 6 hours orally)
  • Clindamycin (300-450 mg every 6-8 hours orally) for penicillin-allergic patients

Moderate Cellulitis with Systemic Signs

• Add coverage for methicillin-susceptible S. aureus (MSSA)
  • Dicloxacillin (500 mg every 6 hours orally)
  • Cephalexin (500 mg every 6 hours orally)
  • Clindamycin (300-450 mg every 6-8 hours orally)

Severe Cellulitis or Special Circumstances

• Consider MRSA coverage if any of the following risk factors:

  • Penetrating trauma
  • Evidence of MRSA infection elsewhere
  • MRSA nasal colonization
  • Injection drug use
  • Systemic inflammatory response syndrome (SIRS)
  • Purulent drainage

• MRSA coverage options:

  • Vancomycin (15 mg/kg every 12 hours IV)
  • Linezolid (600 mg every 12 hours IV or orally)
  • Doxycycline (100 mg twice daily)
  • Trimethoprim-sulfamethoxazole (1-2 DS tablets twice daily)

• For severely compromised patients (malignancy on chemotherapy, neutropenia, severe immunodeficiency):

  • Vancomycin plus piperacillin-tazobactam or imipenem/meropenem

Duration of Treatment

• 5-day course is recommended for uncomplicated cellulitis 1, 2
• Extend treatment if infection has not improved after 5 days 1

Adjunctive Measures

1. Elevation of the affected area to reduce edema 1
2. Treatment of predisposing factors such as:
   • Edema
   • Underlying skin disorders
   • Venous insufficiency
   • Toe web abnormalities 1
3. Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adults to reduce inflammation 1

Hospitalization Criteria

Hospitalize patients with:

• Systemic inflammatory response syndrome (SIRS)
• Altered mental status
• Hemodynamic instability
• Concern for deeper or necrotizing infection
• Poor adherence to therapy
• Severe immunocompromise
• Failure of outpatient treatment 1

Management of Recurrent Cellulitis

1. Identify and treat predisposing conditions (edema, obesity, eczema, venous insufficiency, toe web abnormalities) 1
2. For frequent recurrences (3-4 episodes per year):
   • Consider prophylactic antibiotics:
     • Oral penicillin or erythromycin twice daily for 4-52 weeks
     • Intramuscular benzathine penicillin every 2-4 weeks 1

Common Pitfalls and Caveats

1. Misdiagnosis: Many conditions mimic cellulitis including venous stasis dermatitis, contact dermatitis, and lymphedema 3
2. Unnecessary MRSA coverage: Most non-purulent cellulitis is caused by streptococci and does not require MRSA coverage 1, 3
3. Excessive treatment duration: 5 days is sufficient for most cases; longer courses don't improve outcomes but increase antibiotic resistance risk 1, 2
4. Failure to examine interdigital spaces in lower extremity cellulitis, which can harbor pathogens causing recurrent infection 1
5. Overlooking underlying conditions that predispose to cellulitis and recurrence 1, 4

By following this evidence-based approach to cellulitis treatment, clinicians can effectively manage this common infection while minimizing unnecessary antibiotic use and reducing the risk of complications.