Two studies highlight contamination of the hospital environment with C. difficile spores as a major risk factor.

The clinical and financial burdens of Clostridium difficile infection (CDI) are substantial and have been increasing over the last decade. Findings from two recent retrospective cohort studies provide further insights into the risk factors for such infection and could aid in preventive efforts.

Dubberke and colleagues collected data on all patients hospitalized for ≥48 hours at a Missouri medical center in 2003. After exclusion of patients in the bone marrow transplant and leukemia units and individuals with CDI during the preceding 60 days, 35,350 patients remained, including 329 with CDI. Significant risk factors for CDI included higher CDI pressure score (a measure of an individual’s total exposure to infectious CDI patients; odds ratio, 13.0), ≥2 hospitalizations within the preceding 60 days (OR, 2.7), older age (OR, 2.5), receipt of a gastric acid suppressor (OR, 2.1) or an antimotility drug (OR, 2.1), higher number of days receiving high-risk antibiotics (OR, 1.9), albumin level ≤3.5 g/dL on admission (OR, 1.7), and admission to an intensive care unit (ICU; OR, 1.6). A CDI risk prediction model developed using these variables appeared to have excellent but not perfect predictive accuracy, based on statistical measures that evaluate model discrimination.

Shaughnessy and colleagues assessed the effect of room assignment on CDI incidence at a 20-bed ICU in a Michigan medical center from January 2005 through June 2006. Among the 1770 patients with records available for analysis, 87 were determined to have acquired CDI after admission to the ICU. The incidence of CDI was significantly higher among patients admitted to a room in which the previous occupant had had CDI than among patients admitted to a room in which the previous occupant had not had CDI (11.0% vs. 4.6%; P=0.002). This risk factor remained significant after adjustment for age, Apache III score, proton-pump inhibitor use, and antibiotic exposure.

Comment: These studies are limited by their retrospective design and by the potential effect of variables that were not analyzed (nicely demonstrated by the absence of room assignment in Dubberke and colleagues’ model). Notably, however, both studies raise the issue of contamination of the hospital environment with C. difficile spores as a — if not the — major risk factor for nosocomial CDI. This issue deserves much greater attention than it has received in the past.

— Richard T. Ellison III, MD

Published in Journal Watch Infectious Diseases March 9, 2011