Keflex Dosing for Infected Traumatic Wound Post-Debridement
For an infected traumatic wound status post debridement with normal renal function (creatinine 0.8), administer cephalexin 500 mg orally every 6 hours for 5-7 days. 1
Rationale for Dosing Selection
The FDA-approved dosing for cephalexin in skin and soft tissue infections is 250 mg every 6 hours for mild infections, but 500 mg every 6 hours is appropriate for more severe infections or those caused by less susceptible organisms 1. Your clinical scenario—a traumatic wound with established infection requiring debridement—qualifies as a more severe infection requiring the higher dose.
Treatment Duration
- For contaminated traumatic wounds with established infection (Class III/IV wounds), antibiotic therapy should continue for 5-7 days 2, 3
- This differs from prophylaxis in clean wounds, where 2-3 days suffices 3
- The presence of infection post-debridement indicates therapeutic (not prophylactic) antibiotic use 2
Why This Dose is Appropriate
- Cephalexin achieves urinary concentrations of 500-1000 mcg/mL following 250-500 mg oral doses, providing tissue levels many times the minimum inhibitory concentration for common wound pathogens 4
- The drug is completely absorbed from the upper intestine and rapidly distributed to tissues (excluding CSF), making it ideal for soft tissue infections 4
- For infected wounds requiring debridement, the higher 500 mg dose ensures adequate tissue penetration against Staphylococcus aureus and Streptococcus species 1, 5
Renal Function Consideration
- With a creatinine of 0.8 mg/dL (normal renal function), no dose adjustment is necessary 4
- Dose reduction is only required when creatinine clearance falls below 30 mL/min 4
Critical Management Points Beyond Antibiotics
- Ensure adequate surgical debridement was performed, as antibiotics serve only as adjunct to mechanical removal of contaminated tissue 2
- The wound should remain open or loosely approximated—primary closure is contraindicated in contaminated/infected traumatic wounds 6, 7
- Monitor closely for signs of deeper infection including osteomyelitis or septic arthritis, which would require extended therapy (4-6 weeks for osteomyelitis, 3-4 weeks for septic arthritis) 6
Alternative Regimen if Cephalexin Fails
- If clinical improvement is not seen within 48-72 hours, consider switching to amoxicillin-clavulanate 875/125 mg twice daily for broader anaerobic coverage 2, 6
- This is particularly important if the wound was contaminated with soil, feces, or involved deeper structures 2
Common Pitfall to Avoid
Do not use the 250 mg every 12 hours dosing regimen listed in the FDA label for "uncomplicated" skin infections 1—your patient has a complicated, infected traumatic wound requiring the more aggressive 500 mg every 6 hours regimen to prevent treatment failure and potential complications like osteomyelitis.