What is the recommended treatment for cellulitis of the leg?

Treatment of Cellulitis of the Leg

The first-line treatment for cellulitis of the leg is a 5-day course of antibiotics active against streptococci, such as penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, cephalexin, or clindamycin, with extension if the infection has not improved within this time period. 1, 2

Antibiotic Selection

• For uncomplicated cellulitis without systemic signs of infection, use antibiotics active against streptococci (the most common causative organism): 1, 2

  • Penicillin
  • Amoxicillin
  • Amoxicillin-clavulanate
  • Dicloxacillin
  • Cephalexin
  • Clindamycin

• For moderate infections with systemic signs (fever, tachycardia, confusion, hypotension, leukocytosis), consider coverage for both streptococci and methicillin-susceptible S. aureus (MSSA) 2

• MRSA is an unusual cause of typical cellulitis, and treatment specifically targeting this organism is usually unnecessary in uncomplicated cases 1

• Consider MRSA coverage only in specific situations: 1, 2

  • Cellulitis associated with penetrating trauma
  • Illicit drug use
  • Purulent drainage
  • Concurrent evidence of MRSA infection elsewhere

• Options for MRSA coverage include: 1

  • Intravenous: vancomycin, daptomycin, linezolid, or telavancin
  • Oral: doxycycline, clindamycin, or trimethoprim-sulfamethoxazole (SMX-TMP)

Duration of Therapy

• A 5-day course of antimicrobial therapy is as effective as a 10-day course if clinical improvement has occurred by day 5 1, 2

• Extend treatment if infection has not improved within the initial treatment period 2

Treatment Setting

• Outpatient therapy is appropriate for patients who do not have: 2

  • Systemic inflammatory response syndrome (SIRS)
  • Altered mental status
  • Hemodynamic instability

• Consider hospitalization if: 2

  • Concern for deeper or necrotizing infection
  • Poor adherence to therapy
  • Infection in a severely immunocompromised patient
  • Failure of outpatient treatment

Adjunctive Measures

• Elevate the affected area to promote gravity drainage of edema and inflammatory substances 1, 2

• Identify and treat predisposing conditions: 1, 2

  • Tinea pedis
  • Trauma
  • Venous eczema/stasis dermatitis
  • Edema
  • Obesity
  • Venous insufficiency
  • Toe web abnormalities

• Systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) could be considered in non-diabetic adult patients to reduce inflammation 1, 2

Blood Cultures

• Blood cultures are unnecessary for typical cases of cellulitis 1

• Consider blood cultures in patients with: 1, 2

  • Malignancy
  • Severe systemic features (high fever, hypotension)
  • Unusual predisposing factors (immersion injury, animal bites, neutropenia, severe cell-mediated immunodeficiency)

Prevention of Recurrence

• Identify and treat predisposing conditions such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 1, 2

• For patients with 3-4 episodes of cellulitis per year despite treatment of predisposing factors, consider prophylactic antibiotics: 1, 2, 3

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

Clinical Pearls and Pitfalls

• Cellulitis is a clinical diagnosis characterized by rapidly spreading areas of erythema, swelling, tenderness, and warmth 1, 4

• Venous insufficiency, eczema, deep vein thrombosis, and gout are frequently mistaken for cellulitis 5

• In areas with high prevalence of community-associated MRSA, antibiotics with activity against MRSA (trimethoprim-sulfamethoxazole, clindamycin) may be preferred as empiric therapy 6

• The combination of SMX-TMP plus cephalexin has not been shown to be more efficacious than cephalexin alone in pure cellulitis without abscess, ulcer, or purulent drainage 1

• Recurrent cellulitis is common, with annual recurrence rates of about 8-20%, usually occurring in the same area as the previous episode 1, 4