What is the drug of choice for treating cellulitis?

Drug of Choice for Cellulitis

For typical, uncomplicated cellulitis, a beta-lactam antibiotic such as cephalexin, dicloxacillin, or amoxicillin is the drug of choice, as these medications effectively target streptococci, which are the predominant pathogens in most cases of cellulitis. 1

First-Line Treatment Options

Oral Therapy for Uncomplicated Cellulitis

• First choice: Cephalexin 500 mg four times daily or dicloxacillin 500 mg four times daily for 5-7 days 1, 2
• Alternative options:
  • Amoxicillin 500 mg three times daily
  • Amoxicillin-clavulanate 875/125 mg twice daily
  • Clindamycin 300-450 mg four times daily (for penicillin-allergic patients) 1, 3

Duration of Therapy

• 5 days is as effective as 10 days for uncomplicated cellulitis if clinical improvement occurs by day 5 1
• Consider extending treatment if improvement is not noted 4

Special Considerations

MRSA Coverage

Beta-lactam monotherapy is recommended for typical cellulitis without purulent drainage, as MRSA is an unusual cause of typical cellulitis 1. A prospective study showed that treatment with beta-lactams was successful in 96% of cellulitis cases, suggesting MRSA coverage is usually unnecessary 1.

However, consider MRSA coverage in these situations:

• Cellulitis with purulent drainage
• Penetrating trauma (especially from illicit drug use)
• Concurrent evidence of MRSA infection elsewhere
• Failed initial beta-lactam therapy 1

MRSA Treatment Options

If MRSA coverage is needed:

• Oral options: Clindamycin, trimethoprim-sulfamethoxazole (TMP-SMX), or doxycycline 1
• Intravenous options: Vancomycin, daptomycin, linezolid, or telavancin 1

Combined Coverage

If coverage for both streptococci and MRSA is desired:

• Clindamycin alone (covers both pathogens) 1, 3
• Combination of TMP-SMX or doxycycline with a beta-lactam 1

However, a randomized clinical trial showed that adding TMP-SMX to cephalexin was no more effective than cephalexin alone for pure cellulitis 1, 5.

Adjunctive Measures

• Elevate the affected area to promote drainage of edema 1
• Address predisposing conditions (tinea pedis, trauma, venous eczema) 1
• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adults 1

Common Pitfalls to Avoid

1. Overuse of broad-spectrum antibiotics when narrower options are appropriate 4
2. Unnecessary MRSA coverage for typical, non-purulent cellulitis 1, 6
3. Failure to elevate the affected area, which delays resolution 1, 4
4. Inadequate duration of therapy when improvement is slow 1
5. Overlooking underlying conditions that can lead to recurrence or treatment failure 1, 4

Recurrent Cellulitis Management

For patients with recurrent episodes (3-4 per year), consider prophylactic antibiotics:

• Monthly intramuscular benzathine penicillin injections
• Oral penicillin V (1g twice daily)
• Oral erythromycin (250 mg twice daily) 1, 4

By following these evidence-based recommendations, clinicians can effectively treat cellulitis while practicing appropriate antibiotic stewardship.