What is the recommended antibiotic regimen for an adult patient with an open fracture?

Oral Antibiotic Therapy for Open Fractures

Oral antibiotics are NOT recommended for initial management of open fractures—intravenous antibiotics must be administered as soon as possible after injury, ideally within 3 hours, to reduce infection risk. 1, 2

Initial Antibiotic Selection (IV Administration Required)

Type I and II Open Fractures

• Administer cefazolin 2g IV slow infusion as first-line therapy 3, 1
• Reinject 1g if surgical duration exceeds 4 hours 3
• Continue for maximum 24 hours after wound closure 1, 4
• Current evidence does NOT support extended-spectrum coverage (aminoglycosides or broader agents) for these lower-grade fractures 4

Type III Open Fractures

• The Surgical Infection Society recommends AGAINST adding aminoglycosides or extended gram-negative coverage unless bone loss is present 1, 4
• Piperacillin-tazobactam as a single agent is the preferred option if broader coverage is deemed necessary 1
• Traditional cefazolin plus gentamicin remains an alternative, though current guidelines favor simpler regimens 1
• Limit duration to 24 hours after wound closure or maximum 48-72 hours post-injury in absence of infection 1, 4

Type III Fractures WITH Bone Loss

• Add local antibiotic delivery systems (gentamicin-coated implants, antibiotic-impregnated beads, or vancomycin powder) as adjuncts to systemic therapy 1, 4

Beta-Lactam Allergy Alternatives (Still IV)

• Clindamycin 900mg IV slow infusion with reinjection of 600mg if duration exceeds 4 hours 3, 5
• Vancomycin 30mg/kg IV over 120 minutes for severe allergies or MRSA risk, with infusion completed at least 30 minutes before incision 3, 5

Special Contamination Scenarios

• Add penicillin for farm-related injuries or gross contamination to cover Clostridium species 1, 2

Critical Timing Considerations

• Antibiotics MUST be started within 3 hours of injury—delays beyond this significantly increase infection risk 1, 2
• For surgical intervention, administer within 60 minutes before incision 1

Common Pitfalls to Avoid

• Do NOT use oral antibiotics for initial prophylaxis—IV administration is mandatory for adequate tissue penetration 3, 1
• Do NOT extend antibiotics beyond 24 hours after wound closure without evidence of infection—this increases antibiotic resistance without benefit 1, 4
• Do NOT routinely add aminoglycosides to Type III fractures—current high-quality evidence shows no benefit unless bone loss is present 1, 4
• Do NOT use initial wound cultures to guide prophylactic antibiotic choice—these do not correlate with infecting organisms 2

Transition to Oral Therapy

If oral antibiotics are considered after the initial IV prophylaxis period and wound closure, this represents treatment of established infection rather than prophylaxis, and antibiotic selection should be guided by culture results and clinical signs of infection 6