What is the pathophysiology of thrush?

Updated: Jan 17, 2019
  • Author: Mudra Kumar, MD, MRCP, FAAP; Chief Editor: Russell W Steele, MD  more...
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Answer

C albicans causes thrush when normal host immunity or normal host flora is disrupted. Overgrowth of yeast on the oral mucosa leads to desquamation of epithelial cells and accumulation of bacteria, keratin, and necrotic tissue. This debris combines to form a pseudomembrane, which may closely adhere to the mucosa. This membrane is usually not large but may rarely involve extensive areas of edema, ulceration, and necrosis of the underlying mucosa.

Affected neonates are typically colonized by C albicans during passage through the birth canal. Hence, the risk for thrush is increased when the mother has an active vaginal yeast infection. Other sources of transmission to neonates include colonized breasts (for breastfed infants), hands, and/or improperly cleaned bottle nipples. Kissing has also been implicated.

C albicans frequently and asymptomatically inhabits the GI tract of many children and adults, and the GI tract has been implicated as a reservoir for yeast contamination of the perineum. Thus, candidal diaper rash frequently occurs in conjunction with thrush.

A systematic review and meta-analysis reported that the prevalence of oral candidiases caused by non-albicans Candida species in sub-Saharan African HIV patients was 33.5% [95% confidence interval (CI) 30.9-36.39%]. Non-albicans Candida species found included C. glabrata (23.8%; 109/458), C. tropicalis (22%; 101/458) and C. krusei (10.7%; 49/458). [1]  


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