The incidence of Clostridium difficile infection (CDI) has increased in the past decade, despite intensified efforts at prevention including infection control and antimicrobial stewardship.1 This has led to the exploration of additional means to reduce the incidence of primary CDI, including vaccines,2 fecal microbiota transplantation,3 isolation of colonized patients,4 and probiotics. Probiotics are an attractive option because they are widely available, inexpensive, and administered easily.