What is the recommended dose and frequency of cefalexin (cephalexin) for treating surgical wound infections?

Cefalexin Dosage for Surgical Wound Infections

For treating surgical wound infections, cefalexin should be administered at a dose of 500 mg orally every 6 hours for adults, with treatment typically continued for 7-14 days depending on infection severity. 1, 2

Recommended Dosing Regimen

Adults:

• Standard dose: 500 mg orally every 6 hours
• Daily dose range: 1-4 g divided throughout the day
• Duration: 7-14 days (similar to cystitis therapy guidelines) 2

Pediatric Patients:

• Standard dose: 25-50 mg/kg/day divided into 4 doses
• For severe infections: Dosage may be doubled to 50-100 mg/kg/day 2

Treatment Considerations

Infection Severity Assessment:

• Mild to moderate surgical wound infections:

  • Standard dose of 500 mg every 6 hours is typically sufficient
  • Consider incision and drainage as primary treatment 1
  • Suture removal plus incision and drainage should be performed for surgical site infections 1

• Severe infections:

  • Higher doses may be required (up to 4g daily)
  • Consider parenteral cephalosporins if daily doses greater than 4g are needed 2
  • For infections with systemic response (erythema/induration extending >5 cm from wound edge, fever), adjunctive systemic antimicrobial therapy is beneficial 1

Treatment Duration:

• Evidence suggests that shorter courses may be effective in certain situations
• A study comparing 2-day versus 5-day prophylactic treatment with cefalexin 500 mg QID showed similar infection rates (8.57% vs 7.14%) 3
• However, for established infections rather than prophylaxis, a 7-14 day course is typically recommended 2

Special Considerations

Alternative Antibiotics for Cefalexin Allergy:

• First choice: Vancomycin 30 mg/kg IV, infused over 120 minutes 4
• Alternative: Clindamycin 900 mg IV, infused slowly 4

Surgical Site Specific Considerations:

• For trunk or extremity surgical sites away from axilla or perineum:
  • Cefalexin 500 mg every 6 hours orally is appropriate 1
• For axilla or perineum surgical sites:
  • Consider adding metronidazole for anaerobic coverage 1

Potential Pitfalls

1. Inadequate drainage: Antibiotic therapy alone without proper surgical drainage may lead to treatment failure. Ensure adequate incision and drainage of surgical site infections 1

2. Inappropriate duration: Extending antibiotic therapy beyond necessary duration increases risk of resistance development. Limit treatment to 7-14 days for most infections 2

3. Failure to reassess: Regular reassessment of the wound is essential. If no improvement is seen within 48-72 hours, consider:

   • Inadequate drainage
   • Resistant organisms
   • Need for broader spectrum antibiotics

4. MRSA consideration: In areas with high MRSA prevalence, cefalexin may be ineffective. Consider adding or switching to MRSA-active agents if suspected 1

By following these guidelines, surgical wound infections can be effectively managed with cefalexin, with appropriate adjustments made based on clinical response and local antimicrobial resistance patterns.