Early prophylactic antibiotics effect on infection rate in blunt open fractures

Background: Open fractures represent a commonly encountered traumatic injury with complex challenges, the most notorious being infection. Antibiotic prophylaxis demonstrates a critical first line of defense; however, there exists some disagreement in the literature related to the efficacy of the timing of antibiotic administration in the setting of open fracture. Hypothesis: This study aimed to determine if antibiotic prophylaxis administered within one hour exhibited an effect on the rate of deep infection across all open long bone fractures, as well as to investigate the role of antibiotic administration (≤ 1 h vs. > 1 h) on superficial and deep infection in upper vs. lower extremity and severity of open fracture based on G-A classification. Methods: Retrospective review was performed at one Level 1 trauma center including patients ≥ 18 years old identified through query of the trauma quality improvement program (TQIP) database, directly admitted with open long bone fractures from blunt injury between January 1, 2019 to March 31, 2023. Fisher exact test and chi squared test were performed for categorical variables. Non-parametric Mann Whitney U-test was used for continuous variable analysis. Non-normally distributed variables were reported as median (95% CI). P-value < 0.5 determined significance. Results: Of 477 patients, 270 received antibiotics ≤ 1 h from arrival (EAbx, mean time to antibiotics 0.58 ± 0.26 h) and 207 > 1 h from arrival (DAbx, 2.35 ± 2.45 h). There were 34 (12.6%) deep infections in EAbx and 29 (14.1%) in DAbx (p = 0.651). Lower extremity injuries demonstrated increased deep (16.6% vs. 5.6%, p = 0.001) and superficial (21% vs. 13.2%, p = 0.044) infections compared to upper extremity injuries. G-A type III injuries demonstrated the highest combined infection rates at 39.9% vs. 12.3% and 24.5% (p < 0.001) for type I and II, respectively. Conclusion: This analysis reaffirms elevated risk in lower extremity and G-A Type III fractures. Patient-specific and injury-specific risk factors may outweigh accepted recommendations for time thresholds, warranting further investigation. Average time to antibiotics in the DAbx group was 2.35 h which may account for lack of significant findings. However, our recommendation remains to administer antibiotics as soon as possible. Level of evidence: Level III, Therapeutic/Care Management.