Impact of doxycycline on Clostridioides difficile infection in patients hospitalized with community-acquired pneumonia

Background: Antibiotic use is a significant risk factor associated with Clostridioides difficile (C difficile) infection (CDI). Community -acquired pneumonia (CAP) is a common infection leading to hospital admission and the use of antibiotics that are highly associated with CDI. It has been proposed that doxycycline, a tetracycline antibiotic, may be protective against CDI. Methods: A retrospective analysis was conducted in hospitalized patients in Veterans Affairs Hospitals across the United States to determine if doxycycline was associated with a decreased risk of CDI. The primary outcome was the development of CDI within 30 days of initiation of doxycycline or azithromycin, as part of a standard pneumonia regimen. Results: Approximately 156,107 hospitalized patients who received care at a Veterans Affairs Hospital and were diagnosed with CAP during the study timeframe were included. A 17% decreased risk of CDI was identified with doxycycline compared to azithromycin when used with ceftriaxone for the treatment of pneumonia (P = .03). In patients who had a prior history of CDI, doxycycline decreased the incidence of CDI by 45% (odds ratio 0.55; P = .02). Conclusions: Doxycycline is associated with a lower risk of CDI compared to azithromycin when used for atypical coverage in CAP. Thus, patients who are at such risk may benefit from doxycycline as a first -line agent for atypical coverage, rather than the use of a macrolide antibiotic, if Legionella is not of concern. (c) 2023 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.