Objective: The aim of this study was to optimize a method for Candida albicans biofilm formation that could be used for testing new antifungal molecules.
Methods: The C. albicans MYA-274 biofilms were formed on acrylic resins discs in batch culture at 37oC, 5% CO2 for a total of 7 days. Yeast-based medium containing 1% glucose was changed every 24 h from days 1 through 7. At the end of each day, the biomass, colony formation unit (cfu) and the pH of the media were measured. In addition, the biofilm morphology was evaluated using a combination of fluorescence imaging techniques and Environmental Scanning Electron Microscopy. Fluconazole (250µg/ml) was used as gold standard treatment against mature biofilm.
Results: During the course of the 7 days, the pH of the solution dropped from 6.5 to 4.5. The biomass and cfu reach their plateaus at day 4 of biofilm development. The yeast-to-hypha transition formations were observed from day 2. The treatment with Fluconazole reduces statistically the fungal viability however the structural organization of the biofilm remained intact after the treatment.
Conclusion: In the proposed method, the in vitro Candida biofilm reaches its peak after 4 days, and it is possible to see an exponential growth of the biofilm; more studies are needed to further elucidate the virulence mechanisms. The optimized model can be used to evaluate new antimicrobial agents.
Acknowledgement: Supported by NIH/NCCAM 1K99AT006507-01
Keywords: Biofilm, Candida albicans and Microbiology