lostridium difficile infection (CDI) is the most common cause of diarrhea in the hospital and is responsible for an estimated 27 000 deaths annually in the United States. 1 Clostridium difficile infection occurs when there is a susceptible host and sufficient exposure to the organism. Many factors may increase host susceptibility to CDI, but the most crucial host-related risk factor is exposure to antibiotics. 2 Antibiotics are a risk factor for CDI not only when they are assessed at the level of the individual patient but also when they are assessed at the level of the hospital ward, 3,4 the level of the institution, 5 and the regional level. 6 Exposure to C difficile is common in the hospital because C difficile spores are capable of persisting in the environment for months. 7 High counts of C difficile spores can be detected in the stool of infected or colonized individuals, and C difficile can be readily cultured from the beds, bed rails, floors, and walls of hospital rooms where prior occupants have had CDI. 8,9 When individuals enter a new environment, they rapidly acquire C difficile as well as the other microorganisms that are present. 10 When one hospital roommate has CDI, patients who share that room are at increased risk for CDI. 11 Furthermore, when the previous occupant of a given hospital room has CDI, the subsequent patient in that room is at increased risk for CDI. 12 It is uncertain how antibiotics or other CDI risk factors might act on one patient to increase risk for CDI in a subsequent patient who shares the same hospital environment. We examined whether receipt of antibiotics by prior occupants of OBJECTIVE To assess whether receipt of antibiotics by prior hospital bed occupants is associated with increased risk for CDI in subsequent patients who occupy the same bed.
DESIGN, SETTING, AND PARTICIPANTSThis is a retrospective cohort study of adult patients hospitalized in any 1 of 4 facilities between 2010 and 2015. Patients were excluded if they had recent CDI, developed CDI within 48 hours of admission, had inadequate follow-up time, or if their prior bed occupant was in the bed for less than 24 hours.
MAIN OUTCOMES AND MEASURESThe primary exposure was receipt of non-CDI antibiotics by the prior bed occupant and the primary outcome was incident CDI in the subsequent patient to occupy the same bed. Incident CDI was defined as a positive result from a stool polymerase chain reaction for the C difficile toxin B gene followed by treatment for CDI. Demographics, comorbidities, laboratory data, and medication exposures are reported. RESULTS Among 100 615 pairs of patients who sequentially occupied a given hospital bed, there were 576 pairs (0.57%) in which subsequent patients developed CDI. Receipt of antibiotics in prior patients was significantly associated with incident CDI in subsequent patients (log-rank P < .01). This relationship remained unchanged after adjusting for factors known to influence risk for CDI including receipt of antibiotics by the subsequent patient (adjusted hazard ratio [aHR...