What is the recommended treatment for cellulitis?

Treatment of Cellulitis

The recommended first-line treatment for typical non-purulent cellulitis is a 5-day course of an antibiotic active against streptococci, such as penicillin, amoxicillin, dicloxacillin, cephalexin, or clindamycin. 1, 2

Assessment and Classification

• Assess for systemic signs of infection to determine severity and appropriate treatment setting 1
• Cellulitis is a diffuse, superficial, spreading skin infection characterized by rapidly spreading areas of erythema, swelling, tenderness, and warmth 3
• Cultures of blood or cutaneous aspirates are not routinely recommended for typical cases of cellulitis 1, 3
• Blood cultures should be obtained for patients with malignancy, severe systemic features, or unusual predisposing factors 1, 3

Antibiotic Selection Based on Severity

Mild Non-purulent Cellulitis

• Use antibiotics active against streptococci (the most common causative organisms) 1, 4:
  • Penicillin
  • Amoxicillin
  • Dicloxacillin
  • Cephalexin (500 mg four times daily)
  • Clindamycin 1, 2

Moderate to Severe Non-purulent Cellulitis

• Consider coverage for both streptococci and methicillin-susceptible S. aureus (MSSA) 1
• For patients with systemic signs of infection, many clinicians include coverage against MSSA 3
• For severe infections, vancomycin plus either piperacillin-tazobactam or imipenem-meropenem is recommended as a reasonable empiric regimen 3

MRSA Considerations

• MRSA is an unusual cause of typical cellulitis, and treatment specifically targeting MRSA is usually unnecessary 2
• Consider MRSA coverage only in specific situations:
  • Cellulitis associated with penetrating trauma
  • Evidence of MRSA infection elsewhere
  • Nasal colonization with MRSA
  • Injection drug use
  • Purulent drainage
  • Systemic inflammatory response syndrome (SIRS) 2, 3

Duration of Treatment

• A 5-day course of antimicrobial therapy is recommended for uncomplicated cellulitis 1, 2
• Treatment should be extended if the infection has not improved within 5 days 1, 3
• Studies have shown that a 5-day course is as effective as a 10-day course if clinical improvement occurs by day 5 2, 3

Treatment Setting

• Outpatient therapy is recommended for patients without SIRS, altered mental status, or hemodynamic instability 1, 3
• Hospitalization is recommended for patients with:
  • Concern for deeper or necrotizing infection
  • Poor adherence to therapy
  • Severe immunocompromise
  • Failing outpatient treatment 1, 3

Adjunctive Measures

• Elevation of the affected area to promote gravity drainage of edema and inflammatory substances 1, 2
• Treatment of predisposing factors such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 1
• Consider systemic corticosteroids in non-diabetic adult patients to reduce inflammation and hasten resolution 2
• Some evidence suggests that adding anti-inflammatory therapy (such as ibuprofen) to antibiotic treatment may hasten resolution of cellulitis-related inflammation 5

Prevention of Recurrence

• Identify and treat predisposing conditions such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 1
• In lower extremity cellulitis, carefully examine the interdigital toe spaces and treat fissuring, scaling, or maceration to reduce recurrence 3
• For patients with 3-4 episodes of cellulitis per year despite treatment of predisposing factors, consider prophylactic antibiotics 1

Common Pitfalls to Avoid

• Don't extend treatment unnecessarily beyond 5 days if clinical improvement has occurred 2
• Don't automatically add MRSA coverage for typical non-purulent cellulitis without specific risk factors 2, 3
• Don't confuse cellulitis with cutaneous inflammation associated with collections of pus (such as septic bursitis, furuncles, or skin abscesses), which primarily require drainage rather than antibiotics 3
• Don't overlook underlying conditions that may predispose to recurrent cellulitis 6