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.
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.
