Serotype distribution and secretory acid proteinase activity of Candida albicans isolated from the oral mucosa of patients with denture stomatitis

Denture stomatitis is the most common form of oral Candida infection in hum ans. In the current study, the distribution of Candida albicans serotype A and B as well as the activity of the secreted acid proteinase were determin ed in clinical isolates from patients with denture stomatitis. It was found that 70% of individuals with clinical signs of denture stomatitis exhibite d fungal growth, with C. albicans representing the most frequently isolated species (75%). Of the C. albicans isolates, 75% were serotype A and 25% we re serotype B, representing a significant increase of serotype B compared t o a control group of non-denture-wearing HIV-seronegative individuals with oral candidiasis, but no significant difference compared with isolates from HIV-seropositive patients, who also exhibited a high percentage of serotyp e B. The mean secretory acid proteinase activity of C. albicans isolates fr om denture stomatitis patients (2796+/-819 U/l) was statistically not diffe rent from the mean secretory acid proteinase activity in non-denture-wearin g HIV-seronegative individuals (2324+/-1487 U/l). Both values were signific antly lower than the mean secretory acid proteinase activity of C. albicans from HIV-seropositive individuals (4256+/-2372 U/l). No correlation exists between the C. albicans serotype and the amount of secreted acid proteinas e, indicating that serotype and secretory acid proteinase expression are tw o independent pathogenetic factors in oral candidiasis. These results indic ate that there seems to be strain selection for C. albicans serotype B in d enture stomatitis. These results further indicate that increased secretion of the acid proteinase seems to be of pathogenetic significance in the cand idiasis of HIV-seropositive patients but not in denture stomatitis. Neverth eless, the secretory acid proteinase is likely to be an important pathogene tic factor also in denture stomatitis, where an increased secretion of the acid proteinase may not be required because of decreased salivary flow and a low pH under the denture, which will result in a high enzymatic activity.