What is the recommended treatment for cellulitis?

Treatment for Cellulitis

First-line treatment for non-purulent cellulitis should be antibiotics active against streptococci, such as cephalexin, dicloxacillin, or amoxicillin-clavulanate for 5-6 days, with clindamycin as an alternative for penicillin-allergic patients. 1

Antibiotic Selection Algorithm

Uncomplicated Non-Purulent Cellulitis

1. First-line options (target streptococci and methicillin-sensitive S. aureus):

   • Cephalexin 500 mg orally four times daily
   • Dicloxacillin 500 mg orally four times daily
   • Amoxicillin-clavulanate 875/125 mg orally twice daily

2. For penicillin-allergic patients:

   • Clindamycin 300-450 mg orally three times daily
   • Trimethoprim-sulfamethoxazole (TMP-SMX) for β-lactam allergic patients 1

3. Duration: 5-6 day course is typically sufficient 1

Complicated Cellulitis

For patients with systemic inflammatory response syndrome (SIRS), altered mental status, or hemodynamic instability:

1. Hospitalization and IV antibiotics:
   • Vancomycin (primary option for MRSA coverage)
   • For severely compromised patients: vancomycin plus either piperacillin-tazobactam or imipenem/meropenem 1

Important Clinical Considerations

Diagnosis

• Cellulitis is a clinical diagnosis based on acute onset of redness, warmth, swelling, tenderness, and pain 2
• Beware of mimickers: venous stasis dermatitis, contact dermatitis, eczema, lymphedema, and erythema migrans 2

MRSA Coverage

• Despite rising rates of community-acquired MRSA, coverage for typical non-purulent cellulitis is generally not recommended 2
• A randomized controlled trial showed that adding trimethoprim-sulfamethoxazole (which covers MRSA) to cephalexin did not improve outcomes in uncomplicated cellulitis 3

Abscess Management

• If an abscess is present, incision and drainage is the primary treatment
• For simple abscesses, antibiotics may not be needed after adequate drainage 1

Monitoring and Follow-up

• Monitor for clinical improvement within 48-72 hours
• If no improvement occurs, reassess diagnosis and consider alternative antibiotics 1

Adjunctive Measures

• Elevate the affected area to reduce edema and promote drainage of inflammatory substances 1
• Address predisposing factors for recurrence: edema, obesity, venous insufficiency, tinea pedis, venous eczema, interdigital toe space maceration 1
• There is some preliminary evidence that adding an anti-inflammatory agent (ibuprofen) may hasten resolution of cellulitis-related inflammation, though this is not yet part of standard guidelines 4

Common Pitfalls to Avoid

• Misdiagnosis of cellulitis mimics (leading to inappropriate antibiotic use)
• Overuse of broad-spectrum antibiotics for typical non-purulent cellulitis
• Unnecessary MRSA coverage for typical cellulitis
• Inadequate duration of therapy
• Failure to elevate the affected area
• Overlooking underlying conditions that predispose to recurrence 1
• Inadequate drainage of abscesses when present
• Delayed surgical intervention when needed for complicated infections 1

Special Considerations

• Consider blood cultures for patients with malignancy, neutropenia, severe immunodeficiency, or systemic symptoms 1
• Fluoroquinolones (e.g., ciprofloxacin) should be reserved due to increasing resistance patterns and inadequate coverage against streptococci 1