Olinger CR, et al. - Authors ascertained the frequency and impact of under-dosing prophylactic weight-based antibiotics in patients with open tibial fractures. They presumed that patients who did not receive appropriate weight-based dosing of prophylactic antibiotics would have higher rates of infection. In the treatment of open fractures, under-dosing of weight-based antibiotics was seen to be common. The frequency of infection due to cefazolin-sensitive organisms was reduced by appropriate weight-based dosing of cefazolin for prophylaxis in high-grade open tibial fractures. Majority of infections were caused by organisms not susceptible to cefazolin.

Methods

• Experts conducted a retrospective cohort study at level 1 Trauma Center.
• They included patients 18 years of age or older with high-grade (Gustilo-Anderson type IIIA or IIIB) open extraarticular tibial fractures over a 5-year period.
• Deep infection within one year of initial injury was the primary outcome.
• They defined the appropriate weight-based dosing of cefazolin as: at least 1 g for patients <80 kg, 2 g for patients between 80 and 120 kg, and 3 g for patients >120 kg.

Results

• As per data, inclusion criteria was met by 63 patients; 21 (33%) were under-dosed with cefazolin at the time of initial presentation.
• Findings suggested that only 55% among the 20 patients who subsequently developed deep infection, were appropriately dosed with cefazolin; of the patients who did not develop deep infection, 72% were appropriately dosed with cefazolin (P=0.18).
• Univariate analysis demonstrated an association of hypertension with infection (P=0.049).
• A statistically significant reduction in the odds of infection with appropriate weight-based dosing of cefazolin [Odds ratio = 0.42 (95% confidence interval, 0.12–1.48),P=0.177] was not revealed on the multivariable logistic regression analysis of infection due to all organisms.
• In patients who were under-dosed with cefazolin, five of 7 (71%) of the gram positive, non-methicillin-resistant Staphylococcus aureus, infections occurred.
• Compared to 2 (4.8%) of 42 patients who were appropriately dosed (P=0.036), 5 (23.8%) of 21 patients who were under-dosed with cefazolin had gram-positive, non-methicillin-resistant S. aureus infections.