What is the recommended treatment for cellulitis?

Recommended Treatment for Cellulitis

For uncomplicated cellulitis, the first-line treatment is amoxicillin-clavulanate 875/125 mg twice daily orally for 5-7 days. 1, 2

Antibiotic Selection

The choice of antibiotics should target the most common causative organisms:

• First-line options:

  • Amoxicillin-clavulanate 875/125 mg twice daily orally 1
  • Cephalexin 500 mg 3-4 times daily 1, 3

• For penicillin-allergic patients:

  • Clindamycin 300-450 mg orally three times daily 1
  • Doxycycline 100 mg twice daily (excellent activity against Pasteurella multocida, but avoid in children under 8 and pregnant women) 1

• Alternative combination therapy:

  • Trimethoprim-sulfamethoxazole (160-800 mg twice daily) plus metronidazole (250-500 mg three times daily) 1

Treatment Duration

• Standard duration: 5-7 days for uncomplicated skin infections 1, 2
• Extended treatment:
  • 7-10 days for established infections 1
  • 3-4 weeks for septic arthritis 1
  • 4-6 weeks for osteomyelitis 1
• Treatment should continue until at least 48-72 hours after resolution of symptoms 1

MRSA Considerations

MRSA coverage is generally not recommended for non-purulent cellulitis 3. However, consider MRSA coverage in specific high-risk populations:

• Athletes
• Children
• Men who have sex with men
• Prisoners
• Military recruits
• Residents of long-term care facilities
• Those with prior MRSA exposure
• Intravenous drug users 2

Diagnostic Approach

Cellulitis is primarily a clinical diagnosis based on:

• Acute onset of redness, warmth, swelling, tenderness, and pain 3
• Most cases (85%) are nonculturable, making the causative bacteria unknown 2
• When organisms are identified (15% of cases), most are due to β-hemolytic Streptococcus and Staphylococcus aureus 2, 3

Treatment Failure Considerations

If no improvement occurs with appropriate first-line antibiotics, consider:

• Resistant organisms
• Secondary conditions mimicking cellulitis
• Underlying complicating conditions such as immunosuppression, chronic liver disease, or chronic kidney disease 2

Special Considerations

• Immunocompromised patients: May require broader coverage and longer duration of therapy 1
• Recent antibiotic use: Patients who have received antibiotics in the previous 4-6 weeks should be given an alternative class or higher-dose regimen 1
• Blood cultures: Obtain before starting antibiotics if systemic symptoms are present 1
• Wound cultures: Culture any wound drainage or abscess material to guide targeted therapy 1

Common Pitfalls

1. Misdiagnosis: Many conditions mimic cellulitis, including venous stasis dermatitis, contact dermatitis, eczema, lymphedema, and erythema migrans 3

2. Overtreatment for MRSA: Despite rising rates of community-acquired MRSA, coverage for non-purulent cellulitis is generally not recommended unless specific risk factors are present 3, 2

3. Inadequate duration: Stopping antibiotics too early can lead to treatment failure; continue for at least 5 days and until 48-72 hours after symptom resolution 1, 2

4. Failure to address predisposing factors: Addressing underlying conditions can minimize risk of recurrence 2