An outbreak of toxin A negative, toxin B positive Clostridium difficile-associated diarrhea in a Canadian tertiary-care hospital.

Toxigenic Clostridium difficile is a frequent cause of infectious nosocomial diarrhea accounting for up to 25% of nosocomial diarrhea cases. Clinically significant disease is thought to be due almost exclusively to C. difficile strains that produce both toxin A and toxin B. Toxigenic C. difficile produces a broad spectrum of gastrointestinal disease varying from asymptomatic carriage to fulminant pseudomembranous colitis (PMC). Relapses after therapy occur in 7% to 20% of cases. Predisposing conditions and the use of broad spectrum antimicrobials in a susceptible patient population makes C. difficile disease increasingly common in acute-care centres.