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Clostridium Difficile Associated Diarrhea (CDAD)

Clostridium difficile associated disease has increased in frequency and severity throughout North America and Europe over the last 5 years. Strains of C.difficile producing toxins A and/or B are associated with CDAD. The clinical presentation is a continuum that includes asymptomatic carriage, diarrhea, colitis, pseudomembranous colitis, and fulminant colitis. Recurrence is one of the most frustrating and challenging complications of CDAD occurring in 25-30%.
Recent reports of a more virulent strain causing epidemics is due to the emergence of the NAP1 epidemic strain, alternately known as ribotype027 or the hypervirulent strain. This strain carries genetic mutations in the tcdC toxin regulator gene which causes over production of toxins compared to the regular strain and mutations leading to high level quinolone resistance. In Canada, increases in CDAD frequency and mortality were first widely reported in 2004 in Quebec, and then an increase was noticed in all other provinces. According to the Canadian Nosocomial Infection Surveillance Program (CNISP) preliminary results from January 1 to April 30, 2007 showed an incidence of 5.53/1000 patient admissions in Ontario.

The major risk factor for CDAD is antibiotic therapy. Almost all antimicrobial agents except for aminoglycosides have been associated with CDAD. Several studies have found that fluoroquinolones are more strongly linked to CDAD than any other antimicrobial agents. Other risk factors include age greater than 65 years, severe underlying illness and longer hospital stay.

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