Tarah Lynch, Patrick Chong, Jason Zhang, Romeo Hizon, Tim Du, Morag R. Graham, Daniel R. Beniac, Timothy F. Booth, Pamela Kibsey, Mark Miller, Denise Gravel, Michael R. Mulvey, Canadian Nosocomial Infection Surveillance Program

Clostridium difficile are gram-positive, spore forming anaerobic bacteria that are the leading cause of healthcare-associated diarrhea, usually associated with antibiotic usage. Metronidazole is currently the first-line treatment for mild to moderate C. difficile diarrhea however recurrence occurs at rates of 15-35%. There are few reports of C. difficile metronidazole resistance in the literature, and when observed, the phenotype has been transient and lost after storage or exposure of the bacteria to freeze/thaw cycles. Owing to the unstable nature of the resistance phenotype in the laboratory, clinical significance and understanding of the resistance mechanisms is lacking.