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Interaction of Age and Levofloxacin Exposure on the Incidence of Clostridium difficile Infection

Mah, Nathan D. PharmD; Ahern, John W. PharmD; Terhune, Carolyn J. MT(ASCP); Alston, W. Kemper MD, MPH

Infectious Diseases in Clinical Practice:
doi: 10.1097/IPC.0b013e31820994a2
Original Articles

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.

Author Information

From the Fletcher Allen Health Care, University of Vermont College of Medicine, Burlington, VT.

Correspondence to: W. Kemper Alston, MD, MPH, Infectious Diseases Unit, Smith 287, MCHV Campus, Fletcher Allen Health Care, 111 Colchester Ave, Burlington, VT 05401. E-mail:

The authors have no funding or conflicts of interest to disclose.

Presented at the Fifth Decennial International Conference on Healthcare-Associated Infections, Atlanta, GA, March 18-22, 2010 (Abstract 224).

© 2011 Lippincott Williams & Wilkins, Inc.