Relationship between salivary histatin 5 levels and Candida CFU counts in healthy elderly

Few epidemiological studies have confirmed the antifungal activity of histatin 5 in saliva against Candida species. The purpose of this study was to examine the relationship between concentrations of histatin 5 and the number of cultivable Candida in saliva samples from elderly.

Whole saliva samples were obtained from 124 elderly people, 65 years or older, living in a rural community. The concentrations of histatin 5 in saliva samples were determined by the enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody. Total colony-forming units (CFUs) were counted on a selective medium for Candida. Multiple linear regression analysis was performed to determine the independent contribution of explanatory variables to Candida CFUs using age, sex, histatin 5 concentration and type of denture prosthesis as independent variables.

Saliva samples from 104 subjects (84%) were candidal colony-positive. The youngest group (65-69 years old) showed significantly smaller Candida CFU counts than those in the older group. The mean Candida CFU count of denture wearers was significantly higher than that of non-denture wearers. Significantly negative associations were found between Candida CFU counts and histatin 5 level in the oldest group (p < 0.05) and in the full-denture wearers (p < 0.01). Multiple linear regression analysis revealed that Candida CFU counts were mostly associated with type of dentures, followed by histatin 5 concentration.

Possible activity of histatin 5 against Candida in whole saliva of elderly people was epidemiologically confirmed. The area covered by the prostheses was a strong factor associated with the Candida CFU count.