What is the recommended treatment for cellulitis?

Treatment of Cellulitis

Recommended Antibiotic Therapy and Duration

For uncomplicated nonpurulent cellulitis, use a 5-day course of antibiotics active against streptococci, such as penicillin, amoxicillin, cephalexin, or clindamycin, and extend treatment only if the infection has not improved by day 5. 1, 2

Antibiotic Selection Based on Severity

Mild nonpurulent cellulitis (no systemic signs):

• First-line oral options include penicillin, amoxicillin, dicloxacillin, cephalexin (500 mg four times daily), or clindamycin 1, 2, 3
• These agents provide adequate coverage against streptococci, which are the predominant causative organisms 1, 4
• Blood cultures and tissue aspirates are not routinely needed for typical cases 1, 2

Moderate nonpurulent cellulitis (systemic signs present):

• Consider adding coverage for methicillin-susceptible Staphylococcus aureus (MSSA) in addition to streptococci 1, 2
• Appropriate agents include cephalexin or dicloxacillin 1, 2

Severe nonpurulent cellulitis or specific risk factors:

• Use antibiotics effective against both MRSA and streptococci if the patient has: penetrating trauma, evidence of MRSA infection elsewhere, nasal MRSA colonization, injection drug use, purulent drainage, or systemic inflammatory response syndrome (SIRS) 1, 2
• Vancomycin is recommended for severe infection requiring inpatient management 1
• Important caveat: MRSA coverage is not routinely needed for typical nonpurulent cellulitis without these specific risk factors 1, 3, 5

Treatment Duration

• A 5-day course is sufficient for uncomplicated cellulitis 1, 2, 3
• Extend treatment beyond 5 days only if clinical improvement has not occurred 1, 2
• The evidence supporting shorter courses comes from multiple RCTs showing similar clinical outcomes between 5-6 days versus 10-12 days of therapy 1
• Common pitfall: Avoid unnecessarily extending treatment beyond 5 days if the patient is improving clinically 3

Treatment Setting Determination

Outpatient management is appropriate for patients without:

• Systemic inflammatory response syndrome (SIRS) 1, 2, 3
• Altered mental status 1, 2, 3
• Hemodynamic instability 1, 2, 3

Hospitalization is indicated for:

• Concern for deeper or necrotizing infection 1, 2, 3
• Poor adherence to therapy 1, 2, 3
• Severe immunocompromise 1, 2, 3
• Failure of outpatient treatment 2

Adjunctive Measures

Elevation and predisposing factor management:

• Elevate the affected area to promote drainage of edema and inflammatory substances 1, 2, 3
• Examine and treat interdigital toe spaces for fissuring, scaling, or maceration in lower extremity cellulitis, as this can reduce recurrence 1
• Address underlying conditions such as edema, obesity, eczema, venous insufficiency, and tinea pedis 1, 2, 6

Anti-inflammatory therapy:

• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adults to reduce inflammation and hasten resolution 3
• One small study showed that adding NSAIDs (ibuprofen 400 mg every 6 hours for 5 days) to antibiotics significantly shortened time to complete resolution 7

Prevention of Recurrent Cellulitis

For patients with frequent recurrences (3-4 episodes per year) despite treating predisposing factors:

• Consider prophylactic antibiotics: oral penicillin, erythromycin, or intramuscular benzathine penicillin 2, 3
• Identify and aggressively manage predisposing conditions at the initial diagnosis 1, 2, 6

Key Clinical Pitfalls to Avoid

• Do not routinely add MRSA coverage for typical nonpurulent cellulitis without specific risk factors 1, 3, 5
• Do not extend treatment automatically to 10-14 days if clinical improvement occurs by day 5 1, 3
• Do not obtain blood cultures for uncomplicated cases without systemic signs 1, 2
• Consider alternative diagnoses (venous stasis dermatitis, contact dermatitis, eczema) if the patient fails to improve with appropriate first-line antibiotics 4, 5