What is the recommended management for cellulitis?

Management of Cellulitis

For typical cases of cellulitis without systemic signs of infection, a 5-day course of antibiotics active against streptococci is recommended as the primary treatment approach. 1

Classification and Initial Assessment

Cellulitis should be classified based on severity to guide management:

• Mild nonpurulent cellulitis: No systemic inflammatory response syndrome (SIRS), normal mental status, hemodynamically stable
• Moderate nonpurulent cellulitis: Presence of systemic signs of infection
• Severe nonpurulent cellulitis: SIRS, altered mental status, hemodynamic instability

Key diagnostic considerations:

• Blood cultures are not routinely recommended for typical cases 1
• Blood cultures should be obtained in patients with:
  • Malignancy on chemotherapy
  • Neutropenia
  • Severe cell-mediated immunodeficiency
  • Immersion injuries
  • Animal bites 1

Antibiotic Therapy

For mild nonpurulent cellulitis (outpatient):

• First-line: Antibiotics active against streptococci 1
  • Penicillin
  • Amoxicillin
  • Dicloxacillin
  • Cephalexin
  • Clindamycin

For moderate nonpurulent cellulitis:

• Consider coverage for both streptococci and MSSA 1
  • Cephalexin
  • Dicloxacillin
  • Clindamycin (covers both)

For severe nonpurulent cellulitis or special circumstances:

• MRSA coverage indicated when associated with:
  • Penetrating trauma
  • Evidence of MRSA infection elsewhere
  • MRSA nasal colonization
  • Injection drug use
  • SIRS 1
  • Options include:
    • Vancomycin (IV)
    • Linezolid (IV or PO)
    • Daptomycin (IV)
    • Clindamycin (if susceptible)
    • TMP-SMX (with caution for streptococcal coverage)

For hospitalized patients with complicated SSTI:

• IV vancomycin
• Linezolid 600 mg twice daily (IV or PO)
• Daptomycin 4 mg/kg/dose IV once daily
• Telavancin 10 mg/kg/dose IV once daily
• Clindamycin 600 mg IV or PO 3 times daily 1

Duration of Therapy

The recommended duration of antimicrobial therapy is 5 days, but treatment should be extended if the infection has not improved within this time period. 1

This shorter duration is supported by recent evidence showing that 5-6 days of appropriate antibiotics is as effective as longer courses for uncomplicated cellulitis 1.

Adjunctive Measures

1. Elevation of the affected area to promote gravity drainage of edema and inflammatory substances 1

2. Treatment of predisposing factors:

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

3. For lower-extremity cellulitis: Carefully examine interdigital toe spaces and treat fissuring, scaling, or maceration to eradicate colonization with pathogens 1

4. Consider systemic corticosteroids in nondiabetic adult patients (prednisone 40 mg daily for 7 days) to hasten resolution 1

Hospitalization Criteria

Hospitalization is recommended if:

• Concern for deeper or necrotizing infection
• Poor adherence to therapy
• Infection in severely immunocompromised patient
• Outpatient treatment is failing
• SIRS, altered mental status, or hemodynamic instability 1

Management of Recurrent Cellulitis

For patients with 3-4 episodes of cellulitis per year despite attempts to treat predisposing factors:

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

Common Pitfalls and Caveats

1. MRSA is an unusual cause of typical cellulitis without abscess or purulent drainage. Empiric MRSA coverage is unnecessary for typical cellulitis unless specific risk factors are present 1.

2. Avoid overtreatment with broad-spectrum antibiotics for uncomplicated cellulitis. A targeted approach against streptococci is appropriate for most cases 1, 2.

3. Weight-based dosing of antibiotics like clindamycin (<10 mg/kg/day) and TMP/SMX (<5 mg TMP/kg per day) is important to prevent treatment failure 3.

4. Worsening inflammation after initiating therapy may occur due to sudden destruction of pathogens releasing enzymes that increase local inflammation, not necessarily treatment failure 1.

5. Misdiagnosis is common - venous insufficiency, eczema, deep vein thrombosis, and gout are frequently mistaken for cellulitis 4.

By following this evidence-based approach to cellulitis management, clinicians can optimize outcomes while minimizing unnecessary antibiotic use and healthcare costs.