Treatment of Cellulitis
For typical cases of cellulitis without systemic signs of infection, an antimicrobial agent active against streptococci should be prescribed for 5 days, with treatment extended if the infection has not improved within this time period. 1
Diagnosis and Assessment
- Cellulitis is an acute bacterial infection of the dermis and subcutaneous tissue that most commonly affects the lower extremities, presenting with local signs of inflammation including warmth, erythema, pain, and lymphangitis 1
- Cultures of blood or cutaneous aspirates, biopsies, or swabs are not routinely recommended for typical cases 1
- Blood cultures should be obtained in patients with malignancy on chemotherapy, neutropenia, severe cell-mediated immunodeficiency, immersion injuries, and animal bites 1
- Carefully examine interdigital toe spaces in lower extremity cellulitis, as treating fissuring, scaling, or maceration may reduce recurrent infection 1
Antimicrobial Treatment Algorithm
Mild Cellulitis (No Systemic Signs)
- First-line therapy: Antimicrobial agent active against streptococci 1
- Options include penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, or cephalexin 1
- Duration: 5 days, extending if no improvement 1
- Setting: Outpatient therapy for patients without SIRS, altered mental status, or hemodynamic instability 1
Moderate Cellulitis (With Systemic Signs)
- Treatment: Systemic antibiotics with coverage against streptococci; many clinicians include coverage against MSSA 1
- Setting: Consider hospitalization if there are concerns for deeper infection or poor adherence to therapy 1
Severe Cellulitis or Special Circumstances
- For patients with risk factors for MRSA (penetrating trauma, evidence of MRSA infection elsewhere, nasal colonization with MRSA, injection drug use, purulent drainage, or SIRS): Vancomycin or another antimicrobial effective against both MRSA and streptococci 1
- For severely compromised patients: Consider broad-spectrum antimicrobial coverage; vancomycin plus either piperacillin-tazobactam or imipenem/meropenem is recommended 1
- Setting: Hospitalization recommended 1
Adjunctive Measures
- Elevation of the affected area to promote gravity drainage of edema and inflammatory substances 1
- Treatment of predisposing factors such as edema, tinea pedis, or underlying cutaneous disorders 1
- Systemic corticosteroids (e.g., prednisone 40 mg daily for 7 days) could be considered in non-diabetic adult patients 1
Management of Recurrent Cellulitis
- Search for local causes such as pilonidal cyst, hidradenitis suppurativa, or foreign material 1
- Drain and culture recurrent abscesses early in the course of infection 1
- Treat with a 5-10 day course of antibiotics active against the isolated pathogen 1
- Consider a 5-day decolonization regimen for recurrent S. aureus infection:
- Intranasal mupirocin twice daily
- Daily chlorhexidine washes
- Daily decontamination of personal items (towels, sheets, clothes) 1
- Identify and treat predisposing conditions such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 1
- Consider prophylactic antibiotics (oral penicillin or erythromycin twice daily for 4-52 weeks, or intramuscular benzathine penicillin every 2-4 weeks) in patients with 3-4 episodes per year despite treatment of predisposing factors 1
Important Considerations
- Even with rising rates of community-acquired MRSA, coverage for non-purulent cellulitis is generally not recommended unless specific risk factors are present 2
- Cellulitis can be difficult to diagnose due to non-infectious mimickers such as venous stasis dermatitis, contact dermatitis, eczema, lymphedema, and erythema migrans 2
- Relapses occur frequently due to persistent post-inflammatory lymphatic damage and prevalence of risk factors 3
- Hospitalization criteria: concern for deeper or necrotizing infection, poor adherence to therapy, severe immunocompromise, or failing outpatient treatment 1