Distribution of CDI incidence rates by category and age groupI a) number of CDI cases per 1000 admissions per year, b) incidence density per 10 000 patient-days, c) cumulative incidence per 100 000 population per year. Abbreviations: CDI, Clostridium difficile infection; HO-HCF, hospital-onset health care facility-associated; ICU, intensive care unit; IM, internal medicine; HCF, health care facility-associated; CA, community-associated; ICD, international classification of diseases; LTCF, long term care facility.