Molecular typing of Candida albicans in oral candidiasis: karyotype epidemiology with human immunodeficiency virus-seropositive patients in comparison with that with healthy carriers.

Candida albicans organisms isolated from the oral cavities of healthy carriers (26 individuals) and compromised hosts (40 human immunodeficiency virus [HIV]-seropositive patients, all showing symptomatic oral candidiasis) were compared by resolving chromosome-sized DNA molecules into electrophoretic karyotypes. Seven- to 10-band electrophoretic patterns were obtained, with significant and reproducible differences in the distributions of the DNA bands. Seven distinct classes were identified and were designated type a (8 bands), type b (8 bands), type c (7 bands), type d (9 bands), type x (10 bands), type y (10 bands), and type z (9 bands). Four of these (types a to d) were the most representative within all of the isolated strains (95.5%), and the other three (types x to z) were observed only once in three HIV-seropositive individuals (4.5%). Only types b and c were isolated from healthy carriers, with the percentage of their isolation being 61.5 and 38.5%, respectively, while all the described karyotypes were isolated from HIV-seropositive patients, with type b being the most frequent (45%); this was followed by types c (25%), a (15%), and d (7.5%). The prevalence of type b and c karyotypes in HIV-infected individuals, as well as in healthy carriers, suggests that commensal strains in the oral cavities of healthy individuals may become the prevalent agents of subsequent oral candidiasis in compromised hosts. However, replacement of the original, commensal strain, if there is one, cannot be excluded in a compromised host, although strain replacement may be more reasonably hypothesized for types a and d, since only these types were isolated at a relative high percentage from the oral lesions of HIV-infected individuals.