Candidiasis: The most common opportunistic mycosis. Caused by species of Candida, especially Candida albicans* – Other important species include C. glabrata, C. parapsilosis, C. tropicalis, and C. krusei. Candida are thermally dimorphic:* – They exist as budding yeast and pseudohyphae at 20 degrees Celsius, and form germ tubes at 37 degrees Celsius. – In the third image in the diagram, we can see a Candida albicans colony that comprises yeast-like cells with filamentous cells on top. Candida are commonly found in our gastrointestinal and urogenital tracts, and on the skin*. – Thus, most infections are endogenous. – Exogenous infections are less common, but are more likely in health care settings. Candidiasis can manifest in several forms throughout the body; we'll organize in terms of superficial and invasive infections. Superficial candidiasis is the result of localized overgrowth. • On mucosal surfaces, overgrowth is visible as whitish plaques and pseudomembranes; • On the skin, overgrowth produces erythematous and/or vesiculopustular lesions. • Mucosal and cutaneous forms are typically easy to treat. • Chronic muco-cutaneous candidiasis is rare, but difficult to treat. – It is the result of T-lymphocyte defects.Examples of common mucosal and cutaneous candidiasis. Oropharyngeal overgrowth can produce thrush,* which manifests as whitish plaques or pseudomembranes over the palate, buccal surfaces, and tongue. – These lesions are generally painless, though they can cause a "cottony" feeling in the mouth and loss of taste. – Oropharyngeal candidiasis can also produce angular cheilitis, which are painful fissures at the corners of the mouth. – Adults who wear dentures can develop a form of oral candidiasis, called denture stomatitis, which is characterized by uncomfortable erythema without plaques. • Esophageal candidiasis produces plaques or pseudomembranes in the esophagus, and produces pain upon swallowing (odynophagia); this is most common in HIV patients with low CD4+ T-cell counts (thus, it is an AIDS-defining illness). • Intra-abdominal overgrowth is associated with hospitalized patients, especially those who have had abdominal surgery. – Infection can involve the peritoneum and/or any of the abdominal viscera. • Cutaneous candidiasis tends to occur in the body folds, where conditions are warm and moist, such as the armpits, under the breasts, and groin area. – The red rash is often itchy, and can become painful. Diaper rash can also be caused by Candida* overgrowth; the red, itchy rash tends to appear in the folds of the groin, buttocks, and external genitalia. • Vulvovaginal candidiasis (aka, vaginal yeast infections) is characterized by whitish plaques, itching, and a foul-smelling discharge. • Invasive candidiasis Occurs as the result of hematological dissemination or trauma that introduces fungi to a novel site. • Infection can be focal, for example, localized within the heart, lungs, brain, bones, or other organ system, or, can be systemic. • Candidemia and dissemination to the viscera is more likely in neutropenic and hospitalized patients. Candida* species are major causes of central-line associated bloodstream infections. Image Credits:“C. Albicans Hyphal Mass.” Wikipedia, October 13, 2018. https://en.wikipedia.org/w/index.php?title=Candida_albicans&oldid=863856627. “Centers for Disease Control and Prevention’s Public Health Image Library (PHIL), #1217. Thrush Candida albicans. PHIL 1217 lores.jpg.” . Accessed October 18, 2018. https://sr.wikipedia.org/sr-el/%D0%94%D0%B0%D1%82%D0%BE%D1%82%D0%B5%D0%BA%D0%B0:Oral_thrush_Aphthae_Candida_albicans._PHIL_1217_lores.jpg.“File:Esophageal Candidiasis.Jpg.” Wikipedia, December 30, 2011. ndoscopic image of esophageal candidiasis, seen on endoscopy of a patient after chemotherapy. Posted under GFDL on permission of patient https://en.wikipedia.org/w/index.php?title=File:Esophageal_candidiasis.jpg&oldid=468437436.Garnhami. “C. Albicans Colony.” Wikipedia, October 13, 2018. https://en.wikipedia.org/w/index.php?title=Candida_albicans&oldid=863856627. KGH. Esophageal Candidiasis Stained by Periodic Acid-Schiff Procedure. December 4, 2005. Personal collection of histopathologic slides. https://commons.wikimedia.org/wiki/File:Esophageal_candidiasis_(2)_PAS_stain.jpg.Zordan, R.E., Miller, M.G., Galgoczy, B.B. T., and Johnson, A.D. “C. Albicans Cells.” Wikipedia, October 13, 2018. https://en.wikipedia.org/w/index.php?title=Candida_albicans&oldid=863856627.