Cellulitis Management
For typical uncomplicated cellulitis without systemic signs, treat with oral antibiotics targeting streptococci (penicillin, amoxicillin, or cephalexin) for 5 days, elevate the affected limb, and address predisposing factors like interdigital tinea or edema 1.
Antibiotic Selection Algorithm
Mild Cellulitis (No Systemic Signs)
- First-line: Oral penicillin, amoxicillin, or cephalexin targeting β-hemolytic streptococci 1, 2
- Do NOT routinely cover MRSA in non-purulent cellulitis, even with rising community-acquired MRSA rates 2
- Blood cultures and tissue sampling are NOT routinely recommended 1
Moderate Cellulitis (Systemic Signs Present)
- Systemic antibiotics are mandatory 1
- Many clinicians include MSSA coverage 1
- Consider hospitalization if SIRS criteria are met 1
Severe Cellulitis (High-Risk Features)
Add MRSA coverage with vancomycin or equivalent if ANY of these risk factors are present 1:
- Penetrating trauma
- Evidence of MRSA infection elsewhere
- Nasal MRSA colonization
- Injection drug use
- Purulent drainage
- SIRS criteria met
Severely Compromised Patients
- Broad-spectrum coverage: Vancomycin PLUS piperacillin-tazobactam or imipenem-meropenem 1
- This applies to patients with malignancy on chemotherapy, neutropenia, severe immunodeficiency, immersion injuries, or animal bites 1
Treatment Duration
5 days is sufficient for most cases 1. This is a strong recommendation based on high-quality evidence. Extend treatment only if infection has not improved within this timeframe 1.
Critical Non-Pharmacological Management
These interventions are as important as antibiotics but frequently overlooked:
Immediate Actions
- Elevate the affected limb 1
- Examine interdigital toe spaces carefully in lower extremity cellulitis 1
- Treat any fissuring, scaling, or maceration between toes—this eradicates pathogen colonization and reduces recurrence 1
Address Predisposing Factors
- Treat underlying edema or lymphedema 1
- Manage venous insufficiency 3
- Control obesity 3
- Restore skin barrier integrity 3
Hospitalization Criteria
Admit if ANY of the following are present 1:
- SIRS criteria met
- Altered mental status
- Hemodynamic instability
- Concern for deeper or necrotizing infection
- Severely immunocompromised patient
- Poor adherence anticipated
Otherwise, outpatient management is appropriate 1.
Common Pitfalls to Avoid
Do not over-culture: Blood cultures and tissue sampling have poor sensitivity and are not indicated in typical cases 1, 4. Reserve cultures for immunocompromised patients or those with specific risk factors 1.
Do not reflexively cover MRSA: The majority of non-purulent cellulitis is caused by β-hemolytic streptococci or MSSA 2, 4. MRSA coverage should be reserved for specific risk factors outlined above 1.
Do not miss pseudocellulitis: Venous stasis dermatitis, contact dermatitis, lymphedema, and DVT can mimic cellulitis 5, 2. These conditions do not require antibiotics and misdiagnosis leads to unnecessary antimicrobial exposure.
Do not ignore interdigital spaces: Failure to examine and treat tinea pedis or toe web maceration is a major cause of recurrent cellulitis 1. This simple intervention can prevent future episodes.
Recurrence Prevention
For patients with recurrent cellulitis, consider a 5-day decolonization regimen 1:
- Intranasal mupirocin twice daily
- Daily chlorhexidine washes
- Daily decontamination of personal items (towels, sheets, clothes)
However, evidence for efficacy in the MRSA era is limited 1. The most effective prevention strategy remains addressing local risk factors, particularly interdigital fungal infections and chronic edema 1, 3.