Exposure to hospital roommates as a risk factor for health care-associated infection.

BACKGROUND: Numerous patient- and hospital-level characteristics have been established as risk factors for the transmission of health care-associated infections (HAIs). Few studies have quantitatively assessed the impact of exposure to hospital roommates on the acquisition of infections. This study evaluated the association between roommate exposures and the risk of HAIs. METHODS: A retrospective cohort of adult patients admitted to a Canadian teaching hospital between June 30, 2001, and December 31, 2005, was studied. Exposures were characterized as total daily roommate exposures and daily unique roommate exposures. Outcomes examined were methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and Clostridium difficile. RESULTS: The number of roommate exposures per day was significantly associated with MRSA and VRE infection or colonization (MRSA: hazard ratio [HR] = 1.10, 95% confidence interval [CI] = 1.05 to 1.15; VRE: HR = 1.11, 95% CI = 1.02 to 1.21), and with C difficile infection (HR = 1.11, 95% CI = 1.03 to 1.19). A significant association also was found for number of unique roommate exposures per day and VRE (HR = 1.15, 95% CI = 1.02 to 1.28). CONCLUSIONS: The significant associations found between daily roommate exposures and the infection outcomes suggest a possible role for limiting patient-to-patient contact in an infection prevention and control program in this facility. These findings have implications for the deployment and design of acute care hospitals.