The Phases of <i>Clostridioides difficile</i> Infection in the United States: The History and Epidemiology of CDI From 1935 to Present

This review combines historical reports and surveillance data to contextualize Clostridioides difficile infection (CDI) in the U.S. as a phased epidemic, currently in the deceleration phase. C. difficile was first isolated in 1935. During a prolonged emergence phase, the organism attracted limited clinical attention. In 1978, C. difficile was established as the cause of antibiotic-associated pseudomembranous colitis and from 1978 to a peak in 2010, CDI was in an acceleration phase characterized by fluoroquinolone-resistant, toxin-overproducing strains, large hospital outbreaks, and incidence rates over 150 per 100,000 population. Beginning around 2010, CDI incidence decreased, with a shift from healthcare-associated to community-acquired CDI. Changes in diagnostics complicate incidence comparison between phases; only recently is it apparent that CDI has entered a deceleration phase characterized by infectious reservoirs and possible increases in immunity. It may behoove us to prepare for a different kind of CDI: community-based and insidious rather than hospital-predominant and explosive.