What is the management of cellulitis?

Management of Cellulitis

For uncomplicated cellulitis, first-line therapy is beta-lactam antibiotics (such as amoxicillin-clavulanate or cephalexin) for 5-10 days, with 5 days being as effective as longer courses for most patients. 1

Initial Assessment and Diagnosis

• Cellulitis presents with erythema, swelling, warmth, and tenderness over the affected area
• Consider common mimics including venous stasis dermatitis, contact dermatitis, deep vein thrombosis, and panniculitis 2
• Determine severity and need for hospitalization based on:
  • Systemic symptoms (fever, tachycardia)
  • Extent of infection
  • Comorbidities (diabetes, immunosuppression)
  • Ability to take oral medications

Antibiotic Selection Algorithm

Non-purulent Cellulitis (No Abscess)

1. First-line therapy:

   • Beta-lactam antibiotics targeting beta-hemolytic streptococci 1
   • Options: Amoxicillin-clavulanate (Augmentin) or cephalexin 500mg four times daily 1, 3
   • Consider high-dose cephalexin (1000mg four times daily) for potentially better outcomes with slightly increased risk of minor adverse effects 4

2. If MRSA is suspected:

   • Risk factors: Previous MRSA infection, recent hospitalization, antibiotic use
   • Options:
     • Clindamycin 600mg orally three times daily
     • Doxycycline plus a beta-lactam
     • TMP-SMX plus a beta-lactam (amoxicillin)
     • Linezolid 600mg twice daily 1

3. For severe infections requiring IV therapy:

   • Vancomycin (for MRSA coverage)
   • Consider hospitalization for patients with systemic symptoms, extensive disease, or comorbidities 1

Purulent Cellulitis (With Abscess)

1. Primary management:

   • Incision and drainage plus antibiotic therapy 1
   • Obtain cultures from abscess material to guide therapy

2. Antibiotic options:

   • Coverage for both beta-hemolytic streptococci and CA-MRSA:
     • Clindamycin alone
     • Doxycycline plus a beta-lactam
     • TMP-SMX plus a beta-lactam
     • Linezolid alone 1

3. For complex abscesses:

   • Empiric broad-spectrum therapy covering Gram-positive, Gram-negative, and anaerobic bacteria 1

Treatment Duration

• Standard duration: 5-10 days, individualized based on clinical response 1
• Evidence shows 5 days is as effective as 10 days for uncomplicated cellulitis 1, 5
• Daily follow-up until definite improvement is noted 1

Special Considerations

• Pediatric patients: Avoid tetracyclines in children under 8 years of age 1
• Perineal infections: Consider ceftriaxone plus metronidazole or fluoroquinolone plus metronidazole 1
• Adjunctive measures:
  • Elevation of affected limb
  • Compression stockings for underlying edema
  • Consider systemic corticosteroids in select adult patients (contraindicated in diabetics and pregnant women) 1

Prevention of Recurrence

• Identify and treat predisposing conditions:
  • Edema
  • Obesity
  • Eczema
  • Venous insufficiency
  • Local trauma sites 1
• Consider prophylactic antibiotics for patients with 3-4 episodes per year despite treatment of predisposing factors 1

Common Pitfalls to Avoid

1. Misdiagnosis: Cellulitis is often misdiagnosed, leading to unnecessary antibiotic use. Consider the differential diagnosis carefully 2, 3

2. Inappropriate antibiotic selection:

   • Avoid using TMP-SMX alone for non-purulent cellulitis (poor activity against streptococci) 1
   • Don't routinely cover for MRSA in non-purulent cellulitis without risk factors 3

3. Failure to drain abscesses: Antibiotics alone are insufficient for purulent infections requiring drainage 1

4. Excessive treatment duration: 5 days is typically sufficient for uncomplicated cases 1, 5