Treatment of Cellulitis
For uncomplicated cellulitis, a 5-day course of antibiotics active against streptococci is the recommended first-line treatment, with extension if the infection has not improved within this timeframe. 1
Antibiotic Selection
First-line therapy:
- For typical cases of cellulitis, use antibiotics active against streptococci, as they are the most common causative pathogens 1
- Recommended oral options include:
Parenteral therapy (for severely ill patients):
- Indicated for patients with severe illness or those unable to tolerate oral medications 1
- Options include:
- Nafcillin (penicillinase-resistant penicillin)
- Cefazolin (first-generation cephalosporin)
- Clindamycin or vancomycin (for patients with life-threatening penicillin allergies) 1
MRSA Considerations
- MRSA is an unusual cause of typical cellulitis without purulent drainage 1
- Coverage for MRSA should be considered in specific situations:
- Cellulitis associated with penetrating trauma
- History of illicit drug use
- Presence of purulent drainage
- Concurrent evidence of MRSA infection elsewhere 1
- When MRSA coverage is needed, options include:
- Intravenous: vancomycin, daptomycin, linezolid, or telavancin
- Oral: doxycycline, clindamycin, or trimethoprim-sulfamethoxazole (SMX-TMP) 1
Important note: A randomized controlled trial showed that adding trimethoprim-sulfamethoxazole to cephalexin did not significantly improve outcomes in uncomplicated cellulitis compared to cephalexin alone in the per-protocol analysis 3, supporting the guideline recommendation that β-lactam monotherapy is appropriate for non-purulent cellulitis 1.
Duration of Therapy
- A 5-day course of antimicrobial therapy is as effective as a 10-day course for uncomplicated cellulitis, provided clinical improvement has occurred by day 5 1
- The 2019 National Institute for Health and Care Excellence (NICE) guideline recommends a course of 5 to 7 days 1
- Treatment should be extended if the infection has not improved after 5 days 1, 2
Adjunctive Measures
- Elevation of the affected area is an important and often neglected aspect of treatment 1
- Promotes gravity drainage of edema and inflammatory substances
- Hastens improvement of symptoms 1
- Treat any predisposing conditions that may have contributed to the infection:
- Tinea pedis
- Venous eczema ("stasis dermatitis")
- Trauma 1
Anti-inflammatory Therapy
- Systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) could be considered in non-diabetic adult patients with cellulitis 1, 2
- A randomized, double-blind, placebo-controlled trial showed that systemic corticosteroids attenuated inflammatory reactions and hastened resolution 1
- Some evidence suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) may also help hasten resolution of cellulitis-related inflammation when added to antibiotic therapy 4
Prevention of Recurrence
- Patients with previous attacks of cellulitis have annual recurrence rates of about 8%-20%, usually in the same area 1
- Risk factors for recurrence include:
- Edema (especially lymphedema)
- Venous insufficiency
- Prior trauma to the area
- Tinea pedis or other toe web abnormalities 1
- Address underlying risk factors to reduce recurrence risk 1
Common Pitfalls and Caveats
- Avoid unnecessary MRSA coverage for typical non-purulent cellulitis 1, 5
- Don't forget to elevate the affected area, which is crucial for treatment success 1
- Be aware that inflammation may worsen after initiating therapy due to pathogen destruction releasing enzymes that increase local inflammation 1
- Consider extending treatment beyond 5 days if clinical improvement is not observed 1
- Cultures of blood, tissue aspirates, or skin biopsies are unnecessary for typical cases of cellulitis but should be obtained for patients with:
- Malignancy
- Severe systemic features (high fever, hypotension)
- Unusual predisposing factors (immersion injury, animal bites, neutropenia, severe cell-mediated immunodeficiency) 1