What is the recommended antibiotic prophylaxis (abx) regimen for patients with open or compound skull fractures?

Antibiotic Prophylaxis for Open or Compound Skull Fractures

For open or compound skull fractures, antibiotics should be started as soon as possible after injury, with first-generation cephalosporins (such as cefazolin) being the first-line agent for most cases. 1

Classification and Initial Management

• Open skull fractures are considered contaminated wounds (class III) and require therapeutic antibiotics rather than just prophylaxis 1
• Antibiotics should be administered immediately upon presentation to reduce the risk of infection 2
• Delaying antibiotic administration beyond 3 hours post-injury significantly increases infection risk 2, 3

Antibiotic Selection

• First-line therapy:
  • For most open skull fractures: Cefazolin 2g IV (weight-adjusted for pediatric patients) 2, 3
  • For severely contaminated fractures: Consider adding an aminoglycoside for enhanced gram-negative coverage 3, 4
  • For beta-lactam allergic patients: Clindamycin 900mg IV or vancomycin 30mg/kg IV are appropriate alternatives 2

Duration of Therapy

• For less severe open fractures (equivalent to Gustilo-Anderson type I and II): Continue antibiotics for 3 days 1, 5
• For severe open fractures (equivalent to Gustilo-Anderson type III): Continue antibiotics for 5 days 1, 5
• Continuing antibiotics beyond recommended duration without evidence of infection increases risk of antibiotic resistance 2, 3

Special Considerations for Skull Fractures

• Despite common practice, evidence from a Cochrane review does not support prophylactic antibiotic use specifically for basilar skull fractures, whether there is evidence of CSF leakage or not 6
• However, when there is an open wound communicating with the fracture, antibiotic therapy is indicated as for any open fracture 1

Adjunctive Therapy

• Antibiotic therapy is an adjunct to proper surgical debridement, not a replacement 1, 3
• Local antibiotic delivery systems (antibiotic-impregnated beads) may be beneficial as adjuncts in severe open fractures 2, 3

Important Clinical Pearls

• Re-dosing is required for prolonged procedures based on the half-life of the antibiotic (cefazolin: re-dose after 4 hours) 2
• When secondary procedures are performed (bone grafting, internal fixation, soft tissue transfers), an additional 72 hours of therapy is recommended 5
• Recent research suggests that bacterial organisms in infected open fractures do not correlate with Gustilo-Anderson classification, which may warrant consideration of broader spectrum coverage in high-risk cases 7

Common Pitfalls to Avoid

• Delaying antibiotic administration beyond the critical first 3 hours post-injury 2, 3
• Continuing antibiotics beyond recommended duration without evidence of infection 2, 3
• Relying solely on antibiotics without adequate surgical debridement 1, 3