Background: Advanced age and antibiotic exposure are established risk factors for Clostridium difficile infection (CDI). Specifically, fluoroquinolones have emerged as important risk factors for CDI. The goal of this study was to examine how age and levofloxacin exposure influence the absolute risk of CDI in an academic medical center.
Methods: This is a retrospective cohort study of nearly 39,000 hospitalized adults stratified by age. Exposure to levofloxacin was measured, and ceftriaxone was chosen as a comparator. The outcome of interest was nosocomial CDI.
Results: The rate of nosocomial CDI in this cohort was 8 per 10,000 patient days. The risk of CDI increased in a linear fashion with age. Nearly 7% of patients received at least 1 dose of levofloxacin, and 2.5% of them developed CDI. Exposure to levofloxacin amplified the linear relationship of age and CDI. Levofloxacin appears to be a greater risk for CDI in this population than ceftriaxone.
Conclusions: This study provides an estimate of the interaction between age and levofloxacin on the absolute risk of CDI. The hospitalized elderly are a vulnerable population, and levofloxacin appears to have a significant impact on their risk of CDI.