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Clostridium difficile infection (CDI) is the most commonly recognized cause of infectious diarrhea in hospitals and long-term care facilities.1 The incidence of CDI is difficult to establish because it is not a reportable disease in the United States. It is estimated that there are at least 500,000 cases in US hospitals and nursing homes per year resulting in 30,000 deaths.2 Approximately 4.6 cases per 10,000 patient admissions was the incidence noted in data from the Canadian surveillance studies conducted in hospitals in 1997 and 2005.3 A recent European hospital-based survey showed a similar incidence of 4.1 cases per 10,000 patient days.4
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The number of patients discharged from the hospital and transferred to long-term care facilities with the diagnosis of CDI doubled between 2000 and 2003. Close to 2% of them carried the diagnosis of CDI.
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The epidemiology of CDI is changing, especially in the last few years. In 2001, the number of patients discharged from the hospital with the diagnosis of CDI increased at a very rapid rate.5 The number of patients older than 65 years was substantially larger than the group aged 45–64 years, representing a 5-fold increase in the number of cases in this age group. The outbreaks in Canada and the United States were considered very severe between 2002 and 2006.6,7 These outbreaks were associated with the use of fluoroquinolones. The strains of the outbreaks in Canada and United States were identical.8 This strain is known by its restriction analysis pattern, B1, by its pulsed-field gel electrophoresis (PFGE) pattern, North American PFGE type 1 (NAPI), or its ribotype name 027. It is now designated and known as NAPI/B1/027.9 This strain accounted for almost all of the infections. The strain has some genetic characteristics that included gene coding for toxins A and B and an 18-base pair deletion in tcdC, a putative negative regulator of expression of toxins A and B. The presence of one or two of these genetic markers is one of the reasons for the increased virulence. The patients infected with the NAPI/B1/027 developed a more severe disease than the patients infected with other strains. This strain, NAPI/B1/027, has spread to 40 states in the United States and 7 Canadian provinces and has caused outbreaks in Europe and Asia, as well.10–12
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The main means of transmission is person to person through the fecal–oral route, usually in in-patients in hospitals and nursing homes.13 The prevalence of asymptomatic colonization in nursing homes is estimated to be between 5% and 7%14 and in hospitals between 7% and 26%.13 There is a significant increased risk of colonization with longer hospitalizations.
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The incubation period from the time of exposure to the development of symptoms is not very well known, but in studies it has been estimated to be 2–3 days.13 Those persons who are colonized with C. ...