What is the recommended antibiotic regimen for uncomplicated cellulitis?

Recommended Antibiotic Regimen for Uncomplicated Cellulitis

For uncomplicated cellulitis, the recommended first-line antibiotic regimen is cephalexin 500 mg orally 3-4 times daily for 5-6 days. 1

First-Line Treatment Options

The Infectious Diseases Society of America (IDSA) recommends the following options for uncomplicated cellulitis:

• Cephalexin: 500 mg orally 3-4 times daily for 5-6 days 1
• Clindamycin: 300-450 mg orally three times daily for 5-6 days 1
• Amoxicillin-clavulanate: 875/125 mg orally twice daily for 5-6 days 1

Treatment Duration

• A 5-7 day course is typically adequate for uncomplicated cellulitis 1
• Evidence supports that 5 days of therapy is as effective as 10 days for uncomplicated cellulitis 2
• Assess clinical improvement within 72 hours of starting therapy 1
• Extend treatment if infection has not improved within 5 days 1

MRSA Considerations

Consider broader coverage if there is:

• History of MRSA infection
• Recent hospitalization
• Penetrating trauma
• Evidence of systemic involvement 1

In areas with high MRSA prevalence, antibiotics with activity against community-associated MRSA (such as trimethoprim-sulfamethoxazole or clindamycin) may be preferred as empiric therapy 3.

Route of Administration

• Oral antibiotics are as effective as parenteral antibiotics for uncomplicated cellulitis 4
• Reserve IV antibiotics for patients with:
  • Systemic inflammatory response syndrome (SIRS)
  • Altered mental status
  • Hemodynamic instability
  • Concern for deeper/necrotizing infection
  • Poor medication adherence
  • Failure of outpatient therapy 1

Monitoring and Follow-up

• Evaluate response within 48-72 hours 1
• If no improvement after 72 hours, consider:
  • Alternative diagnosis
  • Resistant organisms
  • Need for surgical consultation
  • Underlying complicating conditions 1, 5

Supportive Care

• Elevate affected area to reduce edema
• Treat predisposing factors such as interdigital maceration and underlying skin disorders 1

Common Pitfalls to Avoid

1. Failure to recognize MRSA risk factors: In patients with specific risk factors for MRSA, standard beta-lactam antibiotics like cephalexin may be inadequate.

2. Inadequate duration assessment: While 5-6 days is typically sufficient, failure to reassess at 72 hours may miss treatment failures.

3. Missing deeper infection: Always evaluate for signs of deeper or necrotizing infection (crepitus, bullae, skin sloughing) that would require immediate hospitalization and surgical consultation.

4. Overlooking predisposing factors: Treating the infection without addressing underlying causes can lead to recurrence.