Impact of Beta-Lactam Monotherapy on the Rate of Infection for Type III Open Fracture Prophylaxis

The management of open fractures focuses on surgical stabilization and minimization of infectious complications. The Eastern Association for the Surgery of Trauma (EAST) 2011 guideline recommended cefazolin plus an aminoglycoside for Gustilo-Anderson type III open fracture prophylaxis, but guidance documents published in recent years have taken conflicting stances on the need for additional gram-negative coverage and optimal antimicrobial selection. To our knowledge, high-quality data supporting one approach over another remains limited and aminoglycosides can carry significant safety risks. This study evaluated the safety and efficacy of beta-lactam monotherapy compared to beta-lactam plus aminoglycoside regimens for infection prevention in trauma patients with type III open fractures.

This was a non-inferiority retrospective chart review including patients ≥18 years with ICD-10–identified type III open fractures treated at UofL Health – UofL Hospital between January 2022 and December 2024. Inclusion required orthopedic confirmation of open fracture classification and completion of treatment at the institution. Exclusion criteria included pregnancy, incarceration, severe antibiotic allergy, limb amputation due to injury severity, death prior to treatment completion, or receipt of antibiotics for another infection. The primary outcome was the 30-day incidence of skin and soft tissue infection or osteomyelitis. Secondary outcomes included infection rates by beta-lactam agents versus combination therapy, need for surgical debridement or washout, adequacy of empiric culture coverage, antibiotic continuation beyond 72 hours post-injury or 24 hours after adequate tissue coverage, acute kidney injury, toxic aminoglycoside levels, ototoxicity, and Clostridium difficile infection.

Of 76 patients screened, 47 were included (32 beta-lactam monotherapy; 15 combination therapy). Cefazolin was the primary beta-lactam (96.8% monotherapy; 100% combination), and tobramycin was the most common aminoglycoside (73.3%). Infection occurred in 37.5% of monotherapy patients versus 13.3% of combination-therapy patients. These results are preliminary and have not been submitted for statistical analysis.

Final results and conclusions will be presented at the conference.