Abstract
OBJECTIVE To determine the role of unit-based transmission that accounts for cases of early Clostridium difficile infection (CDI) during hospitalization for allogeneic stem cell transplant. SETTING Stem cell transplant unit at a tertiary care cancer center. METHODS Serially collected stool from patients admitted for transplant was screened for toxigenic C. difficile through the hospital stay and genotyping was performed by multilocus sequence typing. In addition, isolates retrieved from cases of CDI that occurred in other patients hospitalized on the same unit were similarly characterized. Transmission links were established by time-space clustering of cases and carriers of shared toxigenic C. difficile strains. RESULTS During the 27-month period, 1,099 samples from 264 patients were screened, 69 of which had evidence of toxigenic C. difficile; 52 patients developed CDI and 17 were nonsymptomatic carriers. For the 52 cases, 41 had evidence of toxigenic C. difficile on the first study sample obtained within a week of admission, among which 22 were positive within the first 48 hours. A total of 24 sequence types were isolated from this group; 1 patient had infection with the NAP1 strain. A total of 11 patients had microbiologic evidence of acquisition; donor source could be established in half of these cases. CONCLUSIONS Most cases of CDI after stem cell transplant represent delayed onset disease in nonsymptomatic carriers. Transmission on stem cell transplant unit was confirmed in 19% of early CDI cases in our cohort with a probable donor source established in half of the cases.