The epidemiology and microbiology of Clostridium difficile in long-term care and acute care, and characterization of the fecal microbiota in elderly individuals in Ontario, Canada

This thesis is an investigation of Clostridium difficile in elderly patients in an acute care facility (ACF) and residents in a long-term care facility (LTCF) in southern Ontario, Canada. The first part of this thesis presents the findings of a cross-sectional study that describes the epidemiology and microbiology of C. difficile in elderly individuals. C. difficile was isolated from 92/410 (22.4%) ACF and 89/474 (18.8%) LTCF samples. Ribotypes 027 (35%) and 020 (10.4%) predominated the LTCF while ribotypes AI-82/1 (20.7%) and ribotype O (14.1%) predominated the ACF (P=0.031). In the LTCF, C. difficile colonization was associated with a history of Proton Pump Inhibitor (PPI) use (OR=2.05, P=0.003, 95% CI=1.20-3.49), and the interaction terms of male residents with prior medical leave of absence (OR=11.28, P=0.011. 95% CI=1.70-74.87), and a prior history of C. difficile infection (CDI) combined with fluoroquinolone use (OR=39.30, P=0.032, 95% CI=0.032). In the ACF, C. difficile colonization was associated with length of stay (OR=1.00, P=0.037, 95% CI=0.10-1.00), feeding through a tube (OR=4.83, P=0.001, 95% CI=1.95-11.97), antibiotic use (OR=4.36, P=0.050, 95% CI=1.00-18.95), immunosuppressive therapy (OR=8.09, P=0.001, 95% CI=2.24-29.22), and VRE colonization (OR=19.64, P=0.016, 95% CI=1.73-222.61), and the interaction terms for cephalosporin and fluoroquinolone use (OR=31.13, P=0.022 95% CI=1.51-1077.61), and prior CDI and cephalosporin use (OR=59.59, P=0.044, 95% CI=1.12-2854.07). The second part of this thesis describes the fecal microbiota of elderly individuals from ACF and LTCF, and evaluates the impact of PPIs, antibiotics, facility, and C. difficile colonization on microbial diversity, richness, evenness, community, and structure. Evenness and diversity were not affected by other risk factors. Facility and C. difficile colonization were associated with changes in relative abundance of key taxa. Community membership and structure were affected by facility. The changes identified in this study group, might better shape healthcare approaches in elderly, serving as indicators of health as well as aid in development of novel bacterial therapies. C. difficile colonization remains a complex and challenging issue, with the implications in its development of CDI still unclear. Given the potential for transmission by individuals colonized with C. difficile colonized, this area warrants further study.