What is the recommended treatment for cellulitis?

Treatment of Cellulitis

The recommended first-line treatment for cellulitis is an oral antibiotic targeting aerobic gram-positive cocci, particularly Staphylococcus aureus and Streptococcus species, with dicloxacillin 250 mg every 6 hours for mild to moderate infections and 500 mg every 6 hours for severe infections in adults. 1, 2

Antibiotic Selection and Dosing

First-line Treatment Options:

• Dicloxacillin:
  • Adults: 125-250 mg every 6 hours for mild to moderate infections; 250-500 mg every 6 hours for severe infections 2
  • Children: 12.5 mg/kg/day in equally divided doses every 6 hours for mild to moderate infections; 25 mg/kg/day in equally divided doses every 6 hours for severe infections 2
  • Administration: Take on an empty stomach, at least 1 hour before or 2 hours after meals with at least 4 oz of water 2

Alternative Options:

• Amoxicillin-clavulanate: 875/125 mg twice daily for 5-6 days (particularly effective for breast cellulitis) 1
• Clindamycin: Alternative for penicillin-allergic patients, though may cause gastrointestinal effects 1

Treatment Duration

• Standard duration: 5-7 days for uncomplicated skin infections 1
• Extended duration:
  • 7-10 days if slow response to initial therapy 1
  • 14 days for severe staphylococcal infections 2
  • Continue therapy for at least 48 hours after the patient becomes afebrile, asymptomatic, and cultures are negative 2
  • Longer courses (4-6 weeks) for endocarditis or osteomyelitis 1, 2

Assessment of Severity and Treatment Approach

Mild/Moderate Infections:

• Localized cellulitis without systemic symptoms
• <2 cm of cellulitis
• Oral antibiotics targeting aerobic gram-positive cocci 1

Severe Infections:

• Systemic toxicity or metabolic instability
• Extensive involvement (>2 cm cellulitis)
• Lymphangitic streaking
• Requires hospitalization and IV antibiotics 1

Indications for Hospital Admission

• Systemic inflammatory response syndrome (SIRS)
• Altered mental status
• Hemodynamic instability
• Concern for deeper or necrotizing infection
• Poor adherence to therapy
• Severe immunocompromise
• Failure of outpatient treatment 1

Follow-up and Monitoring

• Follow up within 48-72 hours to assess response to treatment
• Watch for abscess formation (fluctuance, persistent fever despite antibiotics)
• If no improvement after 72 hours of appropriate antibiotic therapy, consider surgical consultation 1

Adjunctive Measures

• Elevation of the affected area to reduce edema
• Treatment of predisposing factors (edema, underlying skin disorders)
• Consider systemic corticosteroids (prednisone 40 mg daily for 7 days) in non-diabetic adult patients 1
• Some evidence suggests NSAIDs (ibuprofen 400 mg every 6 hours for 5 days) may hasten resolution of inflammation 3

Common Pitfalls and Considerations

Diagnostic Pitfalls:

• Misdiagnosis of venous insufficiency, eczema, deep vein thrombosis, or gout as cellulitis 4
• Failure to consider less common pathogens in non-responsive cases 5

Treatment Pitfalls:

• Inadequate assessment of infection severity
• Failure to consider MRSA coverage when risk factors are present
• Inadequate treatment duration
• Failure to address predisposing factors 1

Special Considerations:

• For cellulitis without abscess, adding trimethoprim-sulfamethoxazole to cephalexin does not improve outcomes 6
• Obtain cultures when possible, especially in cases not responding to empiric therapy 5
• Tailor antibiotics based on culture results when available 5