What is the recommended management for cellulitis?

Cellulitis Management

First-Line Antibiotic Selection

For uncomplicated cellulitis, initiate treatment with an antibiotic active against streptococci: penicillin, amoxicillin, amoxicillin-clavulanate, dicloxacillin, cephalexin, or clindamycin. 1

• β-hemolytic streptococci and methicillin-sensitive Staphylococcus aureus (MSSA) cause the majority of identifiable cellulitis cases 2, 3
• MRSA coverage is NOT routinely necessary for typical, non-purulent cellulitis 1, 3
• MRSA-targeted therapy should be reserved for specific high-risk scenarios: penetrating trauma, purulent drainage, concurrent MRSA infection elsewhere, or high-risk populations (athletes, prisoners, military recruits, long-term care residents, IV drug users) 1, 2

Specific Antibiotic Regimens by Severity

Mild, uncomplicated cellulitis (outpatient):

• Cephalexin, dicloxacillin, penicillin, or amoxicillin as first-line agents 1
• Clindamycin for penicillin-allergic patients 1

Moderate cellulitis with systemic signs:

• Coverage for both streptococci and MSSA 1
• High-dose amoxicillin-clavulanate provides comprehensive coverage 4

Facial cellulitis:

• High-dose amoxicillin-clavulanate as first-line for comprehensive streptococcal and staphylococcal coverage 4
• Clindamycin for penicillin-allergic patients (covers both streptococci and community-acquired MRSA) 4

Treatment Duration

A 5-day course of antibiotics is as effective as 10 days if clinical improvement occurs by day 5. 1, 4, 5

• Extend treatment duration only if no improvement is seen at 5 days 4, 5
• Total duration should be determined by clinical response, not arbitrary protocols 2

Outpatient vs. Inpatient Management

Treat as outpatient if the patient lacks systemic inflammatory response syndrome (SIRS), altered mental status, or hemodynamic instability. 1, 5

Hospitalization Criteria:

• Concern for deeper or necrotizing infection 1, 5
• Poor adherence to outpatient therapy 1, 5
• Severe immunocompromise 1, 5
• Failure of outpatient treatment 1, 5
• Malignancy with chemotherapy, neutropenia, or severe cell-mediated immunodeficiency 5

Essential Adjunctive Measures

Elevation of the affected extremity is critical to promote gravity drainage of edema and inflammatory mediators. 1, 4, 5

Treatment of Predisposing Conditions:

• Examine interdigital toe spaces for tinea pedis (fissuring, scaling, maceration) and treat aggressively 1, 5
• Address venous insufficiency, lymphedema, and chronic edema 1, 5
• Manage obesity, eczema, and venous eczema 1, 5
• Treat any underlying cutaneous disorders 5

Corticosteroid Consideration:

• Systemic corticosteroids may be considered in non-diabetic adult patients to reduce inflammation 1, 4, 5

Diagnostic Testing

Blood cultures and tissue cultures are NOT routinely recommended for typical cellulitis cases. 5, 3

Obtain Blood Cultures When:

• Malignancy with chemotherapy 1, 5
• Neutropenia or severe cell-mediated immunodeficiency 5
• Severe systemic features 1
• Immersion injuries or animal bites 5
• Unusual predisposing factors 1

Management of Recurrent Cellulitis

Identify and aggressively treat predisposing conditions after the first episode to prevent recurrence. 1, 5

Search for Local Causes:

• Pilonidal cyst, hidradenitis suppurativa, foreign material 5
• Chronic skin conditions requiring ongoing management 4

For Recurrent S. aureus Infections:

• Implement a 5-day decolonization regimen: intranasal mupirocin twice daily, daily chlorhexidine body washes, and daily decontamination of personal items 5

Prophylactic Antibiotics:

• Consider prophylactic antibiotics for patients with 3-4 episodes per year despite treatment of predisposing factors 1, 4, 5

Special Considerations for Periorbital/Facial Cellulitis

Periorbital cellulitis requires daily assessment until definite improvement due to risk of orbital involvement and vision loss. 4

• Monitor for signs of orbital involvement: proptosis, ophthalmoplegia, pain with eye movement, vision changes 4
• Failure to recognize progression from periorbital to orbital cellulitis can result in permanent blindness 4

Critical Pitfalls to Avoid

• Do not use linezolid for routine cellulitis—it is not indicated and carries significant myelosuppression risk requiring weekly CBC monitoring 6
• Do not provide empiric MRSA coverage for typical non-purulent cellulitis—this represents overtreatment 1, 3
• Do not use rifampin as monotherapy or adjunctive therapy for skin and soft tissue infections 4
• Do not miss Gram-negative pathogens in immunocompromised patients—linezolid has no Gram-negative activity and should not be used if Gram-negative infection is suspected 6
• Inadequate antibiotic coverage for both streptococci and staphylococci in facial cellulitis leads to treatment failure 4