What is the treatment for cellulitis of the lower extremities?

Treatment of Cellulitis of the Lower Extremities

For typical cases of cellulitis of the lower extremities without systemic signs of infection, an antimicrobial agent active against streptococci should be prescribed for 5 days, with treatment extended if the infection has not improved within this time period. 1

Antibiotic Selection Algorithm

Mild Cellulitis (No Systemic Signs)

• First-line oral options:
  • Cephalexin 500 mg 3-4 times daily 2
  • Dicloxacillin 500 mg 4 times daily 1
  • Clindamycin 300-450 mg three times daily (for penicillin-allergic patients) 1, 2
  • Amoxicillin-clavulanate 875/125 mg twice daily 2

Moderate Cellulitis (With Systemic Signs)

• Parenteral therapy indicated:
  • Nafcillin or oxacillin 1
  • Cefazolin 1
  • Clindamycin (for penicillin-allergic patients) 1

Severe Cellulitis or High-Risk Situations

• When MRSA is suspected (penetrating trauma, evidence of MRSA elsewhere, nasal colonization with MRSA, injection drug use, purulent drainage, or SIRS):

  • Vancomycin or another antimicrobial effective against both MRSA and streptococci 1, 2

• For severely compromised patients:

  • Vancomycin plus either piperacillin-tazobactam or imipenem/meropenem 1, 2

Treatment Duration

• Standard duration: 5 days 1, 2
• Extend treatment if infection has not improved within 5 days 1
• Reassess after 24-48 hours of treatment initiation to ensure appropriate response 2

Adjunctive Measures

1. Elevation of the affected area 1
2. Treatment of predisposing factors:
   • Edema or underlying cutaneous disorders 1
   • Examine interdigital toe spaces and treat fissuring, scaling, or maceration 1
   • Address tinea pedis, which can be a reservoir for streptococci 1
   • Manage conditions like venous insufficiency, obesity, and lymphedema 3

Hospitalization Criteria

Hospitalization is recommended if:

• Concern for deeper or necrotizing infection
• Poor adherence to therapy
• Infection in a severely immunocompromised patient
• Presence of SIRS, altered mental status, or hemodynamic instability 1

Special Considerations

• Blood cultures are not routinely recommended but should be considered in patients with malignancy on chemotherapy, neutropenia, severe cell-mediated immunodeficiency, immersion injuries, and animal bites 1
• For recurrent cellulitis (3-4 episodes per year), consider prophylactic antibiotics after addressing predisposing factors 2
• Fluoroquinolones like levofloxacin are approved for uncomplicated cellulitis but are not adequate for MRSA infections 1, 4

Common Pitfalls and Caveats

1. Misdiagnosis: Venous insufficiency, eczema, deep vein thrombosis, and gout are frequently mistaken for cellulitis 3, 5
2. Failure to identify and treat predisposing factors: Addressing underlying conditions is crucial to prevent recurrence 1, 3
3. Inadequate coverage for MRSA when indicated: MRSA coverage is not needed for all cases but should be considered in high-risk situations 1, 5
4. Prolonged antibiotic courses: 5 days is sufficient for most uncomplicated cases 1, 2
5. Failure to reassess: If no improvement after 48-72 hours, consider alternative diagnoses or resistant organisms 6

By following this treatment algorithm and addressing predisposing factors, most cases of cellulitis of the lower extremities can be effectively managed with improved outcomes and reduced risk of recurrence.