What are the recommended antibiotics for treating cellulitis?

Recommended Antibiotics for Cellulitis Treatment

For non-purulent cellulitis, first-line treatment is cephalexin 500 mg orally 4 times daily for 5-7 days, with alternative options including dicloxacillin, clindamycin, or amoxicillin-clavulanate. 1

Classification and Antibiotic Selection

Non-purulent Cellulitis (no drainage/exudate/abscess)

• First-line therapy:

  • Cephalexin 500 mg orally 4 times daily for 5-7 days 1
  • Targets β-hemolytic streptococci, which are the primary causative organisms 2, 3

• Alternative options:

  • Dicloxacillin
  • Amoxicillin-clavulanate
  • Clindamycin (if penicillin allergic) 300-450 mg orally three times daily 1

When to Consider MRSA Coverage

Add or switch to MRSA coverage if:

• No response to β-lactam therapy within 48-72 hours 2, 1
• Purulent drainage present
• History of prior MRSA infection
• Patient has risk factors (athletes, children, men who have sex with men, prisoners, military recruits, residents of long-term care facilities, IV drug users) 1, 3

MRSA Coverage Options

• Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 DS tablets twice daily 2, 1
• Doxycycline 100 mg twice daily 2, 1
• Clindamycin 300-450 mg orally three times daily 2, 1
• Linezolid 600 mg twice daily 2

Combination Therapy

If coverage for both β-hemolytic streptococci and MRSA is desired:

• Clindamycin alone 2
• TMP-SMX or tetracycline plus amoxicillin 2
• Linezolid alone 2

Severity-Based Treatment Approach

Mild to Moderate Infections (Outpatient)

• Use oral antibiotics as outlined above
• Duration: 5 days is sufficient for uncomplicated cases 4
• Extend if symptoms not improved after 5 days 2, 1

Severe Infections (Inpatient)

For complicated skin infections requiring hospitalization:

• IV options:
  • Vancomycin 2, 1
  • Linezolid 600 mg IV twice daily 2
  • Daptomycin 4 mg/kg IV once daily 2
  • Telavancin 10 mg/kg IV once daily 2
  • Clindamycin 600 mg IV three times daily 2
• Duration: 7-14 days, individualized based on clinical response 2

Special Considerations

Factors That May Require Longer Treatment

• Advanced age 5
• Elevated C-reactive protein levels 5
• Diabetes mellitus 5
• Concurrent bloodstream infection 5

Pediatric Considerations

• Mupirocin 2% topical ointment for minor skin infections 2
• Avoid tetracyclines in children <8 years due to dental staining risk 2, 1
• For hospitalized children: vancomycin or clindamycin 10-13 mg/kg/dose IV every 6-8 hours 2

Common Pitfalls to Avoid

1. Failure to drain purulent collections - Antibiotics alone are often insufficient for abscesses 1

2. Inappropriate antibiotic selection - Using broad-spectrum antibiotics when narrow-spectrum would suffice 1

3. Inadequate duration - Not extending therapy when clinical response is inadequate 2, 1

4. Missing necrotizing infections - These require immediate surgical consultation and broad-spectrum antibiotics 1

5. Overuse of vancomycin and newer agents - Reserve these for severe infections or confirmed MRSA 1

6. Not reevaluating within 48-72 hours - Important to assess treatment response and consider MRSA coverage if failing initial therapy 1

Recent evidence suggests that oral therapy can be as effective as IV therapy for many patients with cellulitis of similar severity 6, and that 5 days of treatment is often sufficient for uncomplicated cases 4.