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CDI: A Global Perspective of an Epidemic

Authors: Luke F. Chen, MBBS, FRACP; Daniel J. Sexton, MDFaculty and Disclosures



Clostridium difficile is an important nosocomial pathogen that frequently causes complications in hospitalized patients. These complications can be devastating for some patients and ultimately fatal for others. Unfortunately,C difficile is a growing challenge globally and is threatening the safety and lives of our patients.

For a period of 30 years, C difficile was dismissed as an annoying but easy-to-treat infection that sometimes complicated antibiotic use. The pathogenesis, clinical manifestations, and optimal treatment of C difficile infections (CDIs) were extensively studied during the last 2 decades of the 20th century. The subsequent development of enzyme immunoassays for C difficile cytotoxins enabled early diagnosis and treatment of CDIs and obviated the need for diagnostic colonoscopies. The number of severe CDI-related complications, such as toxic megacolon, decreased after these laboratory detection methods became available. Until recently, most patients with CDIs rapidly responded to therapy, and therefore CDIs were not a significant concern to most clinicians and hospital epidemiologists. This complacent attitude, in retrospect, was both naive and wrong for reasons that we will discuss below.

The epidemiology of CDIs has rapidly changed over the last few years. Investigators around the world observed a worrying and unanticipated increase in the incidence of CDIs during the past 5 years. Gradually, it became evident that the world was experiencing an epidemic of CDIs that were associated with increased clinical severity and that were more refractory to conventional therapy.

A new strain of C difficile, known as the NAP1/BI/027 strain, is responsible for many of these severe and difficult-to-treat cases of CDI in North America. This novel strain is capable of producing excess amounts of pathogenic toxins A and B as well as an additional binary toxin. The pathogenesis and clinical features of infections due to the NAP1/BI/027 strain have been extensively studied.

The emergence of a new toxogenic strain of C difficile, however, does not explain increases in the incidence of CDIs in countries where the NAPI/B1/027 strain is infrequently reported. For instance, investigators in Europe and in Asia found that the NAP1/BI/027 strain does not play a prominent role in the epidemic of increased rates of CDI in their region. The exact causes of the epidemic of CDI in Europe and in Asia remain elusive.

The global epidemiology of CDIs is complex and there are many unanswered questions. Several barriers hamper current research in this important area: (1) There is no standard surveillance definition for CDIs[1,2]; (2) there is no consensus definition of a case of CDI that can be used for reporting; and (3) , many countries and states do not routinely collect surveillance data for CDIs.[3]

The following narrative summarizes our current understanding of the changing and complex epidemiology of CDIs in various parts of the world.

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