No abstract

Candida biofilms are a major virulence trait for this yeast. In this study, the biofilm-forming ability of the major medically important clinical and laboratory reference strains was compared. Biofilms were quantified using traditional methods, that is, crystal violet (CV), tetrazolium (XTT) reduction and colony-forming unit assays (CFU), and two new methods: an automated cell counter (ACC) and biofilm suspension turbidity (BST) method. Biofilms could be categorized based on biofilm biomass (high, medium and low) and growth state (high and low). Candida albicans genotypes, A, B and C, showed medium biofilm mass and low growth rate, and only one C. albicans laboratory strain, ATCC MYA-2719, matched this biofilm category. Of all non-albicans Candida species tested, only Candida dubliniensis and Candida glabrata laboratory and clinical isolates had similar biofilm development. The ACC and BST methods for measuring biofilm significantly correlated with CV and CFU biofilm mass measurements. Thus, biofilm mass can be rapidly assessed using biofilm disruptive/cellular nondestructive methods allowing yeast biofilm cells to be used for further analysis. In conclusion, Candida laboratory reference strains and clinical isolates have been shown to form biofilms at different rates; hence for validity, the selection of laboratory reference strains in biofilm studies may be critical for virulence assessment.

These data suggest a significant positive association between the ability of Candida isolates to form biofilms, to produce hydrolytic enzymes, and to metabolize alcohol to acetaldehyde with their ability to promote oral cancer development.

Both smoking and the presence of active carious lesions were found to be positively correlated with the carriage of oral Candida. Individuals who are current smokers are nearly seven times more likely to have oral Candida, and participants with high candidal colonization are more likely to be current smokers. Participants with active carious lesions were also more likely to carry oral Candida.