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Biology of Candida infections

Wiley A Schell, MS
Section Editor
Carol A Kauffman, MD
Deputy Editor
Anna R Thorner, MD


Candidiasis refers to the range of infections caused by species of the fungal genus Candida; these infections can be acute or chronic, localized or systemic. Disseminated candidiasis is life threatening. The great majority of candidiasis is caused by Candida albicans. C. albicans is a common commensal organism in the oropharyngeal cavity, gastrointestinal tract, and vagina of humans but is capable of causing opportunistic infection following disruption of the normal flora, a breach of the mucocutaneous barrier, or a defect in host cellular immunity. C. albicans can be detected as normal flora in about 50 percent of individuals [1].

The basic mycology and pathogenesis of candidiasis will be reviewed here. An overview of Candida infections and the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of candidemia and invasive candidiasis are presented separately; other forms of candidiasis are also discussed elsewhere. (See "Overview of Candida infections" and "Epidemiology and pathogenesis of candidemia in adults" and "Clinical manifestations and diagnosis of candidemia and invasive candidiasis in adults" and "Treatment of candidemia and invasive candidiasis in adults".)


The genus Candida encompasses more than 350 species. They can be found among humans and other mammals, birds, insects, arthropods, fish, animal waste, plants, mushrooms, naturally occurring high-sugar substrates (eg, honey, nectar, grapes) and fermentation products, dairy products, soil, freshwater, seawater, and on airborne particles [2-4].

Infection in humans was first described as oral thrush by Hippocrates in the fifth century BC. In 1853, Charles Robin microscopically observed budding cells and filaments in epithelial scrapings, and he named the fungus Oidium albicans. Subsequently, more than 160 synonyms, including Monilia albicans, were used before Candida albicans became the accepted name for this species.

At least 13 Candida species have caused infection in humans. The most common of these are C. albicans, C. glabrata, C. krusei, C. parapsilosis, and C. tropicalis. C. parapsilosis has been recognized as a heterogeneous species, and it was proposed that it be split into three morphologically and physiologically indistinguishable species: C. parapsilosis, C. metapsilosis, and C. orthopsilosis [5]. Phylogenetic analyses show that C. glabrata is more closely related to Saccharomyces cerevisiae than to the Candida albicans group [6,7], and a taxonomic revision is possible.


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Literature review current through: Sep 2016. | This topic last updated: Sep 21, 2015.
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