Treatment of Cellulitis
For typical non-purulent cellulitis, the recommended first-line treatment is a 5-day course of an antibiotic active against streptococci, such as penicillin, amoxicillin, dicloxacillin, cephalexin, or clindamycin, with extension only if the infection has not improved within this time period. 1, 2, 3
Antibiotic Selection Based on Severity
- For mild cellulitis without systemic signs of infection, use an antimicrobial agent that is active against streptococci, which are the most common causative organisms 1, 3
- First-line oral options include:
- For moderate to severe cellulitis with systemic signs of infection, consider coverage for both streptococci and methicillin-susceptible S. aureus (MSSA) 1, 3
- MRSA coverage is generally not needed for typical non-purulent cellulitis 4
When to Consider MRSA Coverage
- Consider MRSA coverage only in specific situations:
- Cellulitis associated with penetrating trauma
- Evidence of MRSA infection elsewhere
- Nasal colonization with MRSA
- History of injection drug use
- Presence of purulent drainage
- Systemic inflammatory response syndrome (SIRS)
- High-risk populations (athletes, children, men who have sex with men, prisoners, military recruits, residents of long-term care facilities) 1, 5
Duration of Treatment
- A 5-day course of antimicrobial therapy is recommended for uncomplicated cellulitis 1, 3
- Extend treatment only if the infection has not improved within the initial 5-day period 1, 2, 3
- Continuing antibiotics beyond 5 days when improvement has occurred is unnecessary 2, 3
Treatment Setting
- Outpatient therapy is appropriate for patients without SIRS, altered mental status, or hemodynamic instability 1, 3
- Hospitalization is recommended for:
Diagnostic Considerations
- Cellulitis is primarily a clinical diagnosis based on history and physical examination 5, 4
- Cultures of blood or cutaneous aspirates are not routinely recommended for typical cases 1, 3
- Blood cultures should be considered in patients with:
Adjunctive Measures
- Elevate the affected area to promote gravity drainage of edema and inflammatory substances 1, 2, 3
- Treat predisposing factors such as edema, underlying cutaneous disorders, fissuring, scaling, or maceration (especially in interdigital toe spaces) 1, 3
- Consider systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) in non-diabetic adult patients to reduce inflammation and hasten resolution 2
- Some evidence suggests that adding anti-inflammatory therapy (such as ibuprofen) to antibiotics may hasten resolution of cellulitis-related inflammation 6
Prevention of Recurrence
- Identify and treat predisposing conditions (edema, obesity, eczema, venous insufficiency, toe web abnormalities) 3
- For patients with frequent recurrences (3-4 episodes per year) despite management of underlying conditions, consider prophylactic antibiotics such as oral penicillin, erythromycin, or intramuscular benzathine penicillin 2, 3
- In lower extremity cellulitis, carefully examine interdigital toe spaces and treat any fissuring, scaling, or maceration to eradicate colonization with pathogens 1
Common Pitfalls to Avoid
- Don't routinely extend treatment beyond 5 days if clinical improvement has occurred 2, 3
- Don't automatically add MRSA coverage for typical non-purulent cellulitis without specific risk factors 2, 4
- Don't overlook predisposing factors that may lead to recurrent infections 1, 3
- Don't miss clinical mimickers of cellulitis such as venous stasis dermatitis, contact dermatitis, eczema, and lymphedema 4