What is the initial treatment for a patient presenting with cellulitis?

Initial Treatment for Cellulitis

For typical, uncomplicated cellulitis without systemic signs of infection, treatment with cephalexin 500mg orally four times daily for 5-7 days is recommended as first-line therapy. 1

Antibiotic Selection Algorithm

First-Line Treatment Options

• Beta-lactam antibiotics targeting beta-hemolytic streptococci are the first choice for non-purulent cellulitis:
  • Cephalexin 500mg orally four times daily 1
  • Amoxicillin-clavulanate 1
  • Penicillin 1

Alternative Options (for penicillin allergies or specific situations)

• Clindamycin 600mg orally three times daily 1
• Doxycycline (not for children <8 years) 1
• Linezolid 600mg twice daily (for more severe cases) 1, 2

Treatment Duration

• 5-7 day course is recommended for typical cases 1
• Reassess after 5 days and extend treatment until 2-3 days after clinical resolution if inadequate improvement is seen 1
• Longer courses have not demonstrated superior outcomes for uncomplicated cases 1

Special Considerations

For Hospitalized Patients

• IV vancomycin is recommended for patients requiring hospitalization, particularly for MRSA coverage in severe infections 1
• Alternative IV options include:
  • Linezolid 600mg twice daily 1, 2
  • Daptomycin 4mg/kg/day IV 1
  • Telavancin 10mg/kg/day IV 1

For Purulent Cellulitis

• For abscesses with significant cellulitis, incision and drainage plus antibiotic therapy is recommended 1
• Obtain cultures from abscesses and purulent drainage to guide therapy 1

Important Clinical Pearls

Common Pitfalls to Avoid

1. Avoid using TMP-SMX alone for non-purulent cellulitis as it has poor activity against streptococci 1. Despite some research suggesting potential benefits in MRSA-prevalent settings 3, more recent studies show that adding TMP-SMX to cephalexin did not significantly improve outcomes for uncomplicated cellulitis 4, 5.

2. Avoid unnecessary MRSA coverage for typical non-purulent cellulitis. Even with rising rates of community-acquired MRSA, coverage for non-purulent cellulitis is generally not recommended 6, 7.

3. Avoid unnecessarily prolonged antibiotic courses when shorter durations are equally effective, as extended courses increase risk of adverse effects and antimicrobial resistance 1.

Adjunctive Measures

• Elevate the affected area 1
• Apply warm compresses if appropriate 1
• Treat predisposing factors such as edema, underlying skin disorders, or interdigital toe space abnormalities 1

Prevention of Recurrence

• Maintain good personal hygiene 1
• Keep draining wounds covered with clean, dry bandages 1
• Avoid reusing or sharing personal items 1
• For patients with recurrent cellulitis (3-4 episodes per year), prophylactic antibiotics may be considered 1
• Address underlying conditions such as edema, obesity, eczema, and venous insufficiency 1