Medical Management of Cellulitis
For typical cases of cellulitis, treatment should begin with antibiotics active against streptococci, with a recommended duration of 5 days, extending if no improvement is seen. 1, 2
Pathogen Considerations
- Cellulitis is primarily caused by beta-hemolytic streptococci, with Staphylococcus aureus less frequently involved unless associated with penetrating trauma or an underlying abscess 3, 2
- Blood cultures are not routinely recommended for typical cases but should be obtained in patients with malignancy on chemotherapy, neutropenia, severe immunodeficiency, immersion injuries, and animal bites 1
- Examine interdigital toe spaces in lower extremity cellulitis, as treating fissuring, scaling, or maceration may reduce recurrent infection 1, 2
Treatment Algorithm Based on Severity
Mild Cellulitis (Outpatient Management)
- First-line therapy: Oral antibiotics active against streptococci for 5 days 1, 2
- Outpatient therapy is appropriate for patients without systemic signs of infection, altered mental status, or hemodynamic instability 1
Moderate Cellulitis
- Systemic antibiotics with coverage against streptococci and possibly methicillin-susceptible S. aureus (MSSA) 1, 2
- Consider hospitalization for patients with concerns for deeper infection or poor adherence to therapy 1
Severe Cellulitis (Inpatient Management)
- For severe infections or high-risk patients, use vancomycin or another antimicrobial effective against both MRSA and streptococci 2
- For severely compromised patients: vancomycin plus either piperacillin-tazobactam or imipenem/meropenem 2
- Empiric therapy for community-acquired MRSA (CA-MRSA) should be considered for patients at risk or who do not respond to first-line therapy 3
- Indications for MRSA coverage include: penetrating trauma, evidence of MRSA elsewhere, nasal colonization with MRSA, injection drug use, purulent drainage, or SIRS 2
Adjunctive Measures
- Elevate the affected area to promote gravity drainage of edema and inflammatory substances 1, 2
- Treat predisposing factors such as edema, tinea pedis, or underlying cutaneous disorders 1, 2
- Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adult patients to hasten resolution 1, 2
Management of Recurrent Cellulitis
- Identify and treat local causes such as pilonidal cyst, hidradenitis suppurativa, or foreign material 1
- Drain and culture recurrent abscesses early in the course of infection 1
- Consider a 5-day decolonization regimen for recurrent S. aureus infection, including intranasal mupirocin, daily chlorhexidine washes, and daily decontamination of personal items 1
- Address predisposing conditions such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities 1, 2
- For patients with 3-4 episodes per year despite addressing predisposing factors, consider prophylactic antibiotics such as oral penicillin or erythromycin twice daily for 4-52 weeks 2
Special Considerations
- For simple abscesses or boils, incision and drainage is the primary treatment; antibiotics are not needed unless there is extensive surrounding cellulitis 3
- For complex abscesses (perianal, perirectal, or at injection sites), antibiotic therapy is recommended if systemic signs of infection are present 3
- Linezolid (600 mg IV or oral q12h) can be used for complicated skin infections, particularly those caused by MRSA, with a recommended duration of 10-14 days 4
- Cellulitis is a clinical diagnosis - no effective diagnostic modalities exist, and many clinical conditions can appear similar 5, 6
Common Pitfalls to Avoid
- Failure to examine interdigital toe spaces for fissuring, scaling, or maceration that may harbor pathogens 1, 2
- Not elevating the affected area, which delays improvement 2
- Inadequate treatment duration when clinical improvement is not evident after 5 days 1, 2
- Unnecessary coverage for MRSA in typical non-purulent cellulitis cases 6
- Failure to identify and treat underlying conditions that predispose to recurrence 1, 2