What is the recommended treatment for cellulitis?

Treatment of Cellulitis

For typical cellulitis, first-line treatment should be an antibiotic active against streptococci, such as penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, cephalexin, or clindamycin for a 5-day course if clinical improvement occurs. 1

Antibiotic Selection

• Streptococci are the most common causative organisms in cellulitis, with Staphylococcus aureus being less common but still important to consider 1, 2
• For non-purulent cellulitis without systemic signs of infection, use antibiotics active against streptococci such as:
  • Penicillin or amoxicillin 1
  • Amoxicillin-clavulanate 1
  • Cephalexin 500 mg orally four times daily 1
  • Clindamycin 300-450 mg orally four times daily (if penicillin-allergic) 1
• Consider MRSA coverage if the cellulitis is associated with:
  • Penetrating trauma 1
  • Evidence of MRSA infection elsewhere 1
  • Nasal colonization with MRSA 1
  • Injection drug use 1
  • Purulent drainage 1
  • Systemic inflammatory response syndrome (SIRS) 1

Duration of Treatment

• A 5-day course of antimicrobial therapy is as effective as a 10-day course if clinical improvement has occurred by day 5 1, 3
• Treatment should be extended if the infection has not improved within 5 days 1
• Patients should show clinical improvement within 24-48 hours of starting appropriate antibiotics 1

Adjunctive Measures

• Elevation of the affected area to promote gravity drainage of edema and inflammatory substances 4, 1
• Treatment of predisposing conditions such as:
  • Tinea pedis 4, 1
  • Venous eczema ("stasis dermatitis") 4
  • Trauma or other skin conditions that may serve as a portal of entry 4, 1
• Careful examination and treatment of interdigital toe spaces for fissuring, scaling, or maceration that may harbor pathogens 1
• Systemic corticosteroids could be considered in non-diabetic adult patients with cellulitis to reduce inflammation 4, 1

Hospitalization Criteria

• Consider hospitalization if:
  • There is concern for deeper or necrotizing infection 1
  • Poor adherence to therapy is expected 1
  • Patient is severely immunocompromised 1
  • Outpatient treatment is failing 1
  • SIRS, altered mental status, or hemodynamic instability is present 1

Prevention of Recurrence

• Each attack of cellulitis causes lymphatic inflammation and possibly permanent damage 4
• Severe or repeated episodes may lead to lymphedema 4
• Measures to reduce recurrences include:
  • Treating interdigital maceration 4
  • Keeping skin well hydrated with emollients 4
  • Reducing underlying edema through elevation, compression stockings, or diuretic therapy if appropriate 4
• For frequent infections despite preventive measures, prophylactic antibiotics may be reasonable 4, 5
  • Options include monthly intramuscular benzathine penicillin injections of 1.2 MU or oral therapy with twice-daily doses of either 250 mg of erythromycin or 1 g of penicillin V 4

Special Considerations

• Blood cultures are not routinely recommended for typical cases but should be obtained for patients with:
  • Malignancy 1
  • Severe systemic features 1
  • Unusual predisposing factors 1
  • Immunocompromise 1
• For more severe infections requiring intravenous therapy, options include:
  • IV flucloxacillin 6
  • IV vancomycin or daptomycin for MRSA coverage when indicated 7
• Daptomycin has shown similar efficacy to vancomycin or semi-synthetic penicillins in clinical trials for complicated skin and skin structure infections 7