What is the recommended treatment for cellulitis?

Treatment of Cellulitis

For uncomplicated cellulitis, a 5-day course of antibiotics targeting streptococci and methicillin-sensitive Staphylococcus aureus (MSSA) is the recommended first-line treatment, with extension if the infection has not improved within this period. 1

Antibiotic Selection Based on Severity

Mild Non-Purulent Cellulitis (Outpatient)

• First-line options:

  • Cephalexin 500 mg orally four times daily 2
  • Dicloxacillin 500 mg orally four times daily 1
  • Amoxicillin-clavulanate 875/125 mg orally twice daily 1

• For penicillin-allergic patients:

  • Clindamycin 300-450 mg orally three times daily 2

Moderate Non-Purulent Cellulitis

• Systemic antibiotics with coverage against streptococci
• Consider adding coverage for MSSA 1
• Outpatient management appropriate if no SIRS, altered mental status, or hemodynamic instability 1

Severe Non-Purulent Cellulitis

• For MRSA risk factors (penetrating trauma, MRSA infection elsewhere, nasal colonization with MRSA, injection drug use, or SIRS):

  • Vancomycin or another antimicrobial effective against both MRSA and streptococci 1

• For severely compromised patients:

  • Vancomycin plus either piperacillin-tazobactam or imipenem/meropenem 1
  • Hospitalization recommended 1

Duration of Treatment

• 5 days of antibiotics is sufficient for uncomplicated cellulitis 1, 3
• Extend treatment if infection has not improved within 5 days 1
• Reassess patients within 48-72 hours to evaluate response 2

Supportive Measures

• Elevation of the affected area 1
• Treatment of predisposing factors (edema, underlying cutaneous disorders) 1
• For lower-extremity cellulitis, examine interdigital toe spaces and treat fissuring, scaling, or maceration 1

Prevention of Recurrence

• Identify and treat predisposing conditions:

  • Edema
  • Obesity
  • Eczema
  • Venous insufficiency
  • Toe web abnormalities 1, 2

• For patients with 3-4 episodes per year despite addressing predisposing factors, consider prophylactic antibiotics:

  • Oral penicillin or erythromycin twice daily for 4-52 weeks
  • Intramuscular benzathine penicillin every 2-4 weeks 1

Special Considerations

MRSA Coverage

• Not routinely indicated for non-purulent cellulitis 4
• Consider MRSA coverage for:
  • Athletes
  • Children
  • Men who have sex with men
  • Prisoners
  • Military recruits
  • Residents of long-term care facilities
  • Prior MRSA exposure
  • Intravenous drug users 5

Diabetic Patients

• Optimize glycemic control as hyperglycemia is associated with worse infection outcomes 2
• Evaluate for deeper infection or osteomyelitis if response is poor 2

Common Pitfalls

1. Misdiagnosis: Cellulitis can be difficult to diagnose due to mimickers such as venous stasis dermatitis, contact dermatitis, eczema, lymphedema, and erythema migrans 4

2. Overtreatment: Extending treatment beyond 5 days when not necessary 3

3. Inadequate coverage: Failing to consider MRSA in high-risk populations 1

4. Missing underlying conditions: Failing to identify and treat predisposing factors, leading to recurrence 1

5. Overlooking deeper infections: Not recognizing necrotizing soft tissue infections that require surgical intervention 6

6. Unnecessary hospitalization: Most patients with mild to moderate cellulitis can be treated as outpatients 1