Recommended Treatment for Cellulitis
For typical cases of 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 time period. 1
Antibiotic Selection
Uncomplicated Cellulitis (No Systemic Signs)
- First-line therapy should include an antibiotic active against streptococci, such as penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, cephalexin, or clindamycin 1
- Blood cultures or cutaneous aspirates are not routinely recommended for typical cases 1
- A 5-day course of antimicrobial therapy is as effective as a 10-day course if clinical improvement has occurred by day 5 1, 2
Cellulitis with Systemic Signs
- For moderate infections with systemic signs (fever, tachycardia), consider coverage for both streptococci and methicillin-susceptible S. aureus (MSSA) 1
- For severe infections or those associated with specific risk factors (penetrating trauma, evidence of MRSA infection elsewhere, nasal colonization with MRSA, injection drug use, or SIRS), vancomycin or another antimicrobial effective against both MRSA and streptococci is recommended 1
- In severely compromised patients (malignancy on chemotherapy, neutropenia, severe cell-mediated immunodeficiency), broad-spectrum antimicrobial coverage may be considered, such as vancomycin plus either piperacillin-tazobactam or imipenem/meropenem 1
MRSA Considerations
- MRSA is an unusual cause of typical cellulitis, and treatment specifically targeting this organism is usually unnecessary in uncomplicated cases 1
- Coverage for MRSA may be prudent in cellulitis associated with:
- Penetrating trauma, especially from illicit drug use
- Purulent drainage
- Concurrent evidence of MRSA infection elsewhere 1
- If coverage for both streptococci and MRSA is desired for oral therapy, options include clindamycin alone or the combination of either SMX-TMP or doxycycline with a β-lactam 1
Adjunctive Measures
- Elevation of the affected area to promote gravity drainage of edema and inflammatory substances 1
- Treatment of predisposing conditions, such as tinea pedis, trauma, or venous eczema 1
- In lower-extremity cellulitis, careful examination of interdigital toe spaces to treat fissuring, scaling, or maceration that may harbor pathogens 1
- Systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) could be considered in non-diabetic adult patients to reduce inflammation 1, 3
Treatment Setting
- Outpatient therapy is recommended for patients who do not have SIRS, altered mental status, or hemodynamic instability 1
- Hospitalization is recommended if there is:
- Concern for deeper or necrotizing infection
- Poor adherence to therapy
- Infection in a severely immunocompromised patient
- Failure of outpatient treatment 1
Prevention of Recurrence
- Identify and treat predisposing conditions such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 1
- For patients with 3-4 episodes of cellulitis per year despite treatment of predisposing factors, consider prophylactic antibiotics:
- Oral penicillin or erythromycin twice daily for 4-52 weeks
- Intramuscular benzathine penicillin every 2-4 weeks 1
- Continue prophylaxis as long as predisposing factors persist 1
Special Considerations
- Blood cultures should be obtained in patients with malignancy, severe systemic features, or unusual predisposing factors 1
- The most common bacteria causing cellulitis are Staphylococcus aureus, Streptococcus pyogenes, and other β-hemolytic streptococci 4
- Recent evidence suggests that a 5-day course of levofloxacin is as effective as a 10-day course for uncomplicated cellulitis 2