Diagnosis: Oral Candidiasis/Thrush

The Candida species are ubiquitous fungi that colonize more than 50 percent of healthy individuals. These strictly opportunistic pathogens result in various disease manifestations and severity determined by a combination of environmental factors, organism virulence, and host defenses. There are several Candida species (C. parapsilosis, C. tropicalis, C. glabrata, C. krusei, C. pseudotropicalis, C. guilliermondi, C. dubliniensis, and C. inconspicua), but the most commonly responsible for candidiasis is Candida albicans.

Candidiasis can be a limited skin infection or a devastating systemic disease. Immunocompetent individuals tend to have cutaneous infections of warm, moist mucous membranes, resulting in vaginitis, oral thrush, conjunctivitis, endophthalmitis, diaper rash, and infections of the nail and other skin folds. In immunocompromised patients, candidal infections can cause devastating systemic illnesses such as myocarditis, endocarditis, peritonitis, hepatosplenorenal abscesses, and pulmonary and CNS infections. Thrush, also known as acute pseudomembranous oral candidiasis, is the idiom used to describe the classic white-flecked lesions that allegedly resemble the brownish upper plumage and spotted breast of the thrush songbird (family Turdidae).

Oral candidiasis is a familiar mucosal infection frequently seen in the young, old, or those with compromised immunologic systems. It is estimated that 50 percent of patients undergoing radiotherapy and 70 percent undergoing chemotherapy for leukemia and solid tumors suffer from oral candidiasis. (Regezi JA, et al. [1999.] Oral Pathology: Clinical Pathologic Correlations. Saunders, Philadelphia.)

C. albicans is the most common Candida species isolated from the oral cavity in both health and disease conditions (Clin Dermatol 2000;18[5]:553) and the most common infectious cause of esophagitis. One study found 63.1 percent of adults were asymptomatic carriers of C. albicans, with the occurrence of thrush infection at 64.8 percent in adults and 66.7 percent in adults with dentures. (Adv Med Sci. 2006;51[Suppl 1]:77.) Ill-fitting dentures, inadequate oral hygiene, constant irritation by a prosthesis, higher salivary yeast counts, and adherence of C. albicans to denture base materials may explain the higher occurrence of thrush in patients who wear dentures. In children, 43.7 percent have been identified as asymptomatic carriers of C. albicans with a statistically significant higher rate (64%) in children with dental caries. (Adv Med Sci 2006;51[Suppl 1]:187.)

Candidiasis is the most common oral fungal infection seen in association with HIV infection, and has been described as a marker of poor prognosis. (AIDS 1991;5[11]:1339.) Interestingly, the first patient diagnosed with AIDS presented with oral candidiasis. (MMWR 1981;30:250.) Oral candidiasis occurs in more than 60 percent of HIV-infected patients (Oral Dis 1996;2:193), and more than 80 percent of patients diagnosed with AIDS have had thrush. (J Oral Pathol 1991;20: 332.)