Abstract:

Objective To assess the relationship between Candida adhesivity and biofilm formation. Methods Eight Candida strains belonging to 8 species and 1 Saccharomyces cerevisiae strain were cultured in yeast peptone dextrose （YPD） fluid and agar medium respectively. The flocculation and adhesion of Candida were observed. Candida biofilm models were developed in 96-well microculture plates. The kinetics of biofilm formation was measured. Results All the 9 fungal strains had flocculation capability and could adhere to the surface of the yeast peptone dextrose agar medium. After mild shaking of the fluid medium, it is difficult for C. albicans, C. kefyr, C. glabrata and C. tropicalis to resuspend, but easy for Saccharomyces cerevisiae. The adhesivity of C. albicans, C. kefyr, C. glabrata and C. tropicalis was stronger than that of the other Candida strains. Common pathogenic Candida strains could form biofilm, and the metabolic activity of Candida cells in the biofilm increased over time. A significant increment was observed in the ability of C. albicans and C. kefyr to form biofilm compared with the other species （all P < 0.05）, and in that of C. tropicalis and C. glabrata compared with C. krusei, C. parapsilosis and C. gulliermondii（all P < 0.05）. The nonpathogenic Saccharomyces cerevisiae could not form biofilm. Conclusions Candida has the ability to adhere and form biofilm, and the ability varies with Candida species. Moreover, the ability to form biofilm positively correlates with the adhesivity of Candida.

Key words: Flocculation