Exopolymeric matrix of Candida albicans biofilms developed under fluconazole exposure

Objective: To evaluate the exopolymeric matrix of Candida albicans biofilms developed in the presence of fluconazole (FLZ).

Method: Poly(methylmethacrylate) resin discs were fabricated and the surface roughness was standardized. After salivary pellicle formation, biofilms of C. albicans reference strain (ATCC 90028) and five clinical isolates (P01, P34, V17, V18, V29) were developed for 48 hours. Biofilms were grown in YNB medium supplemented with 100 mM glucose and incubated aerobically at 37ºC. In the experimental group, biofilms were developed in the medium containing FLZ at the bioavailable concentration in saliva (2.56 µg/mL). Soluble extracellular, insoluble extracellular and intracellular polysaccharides from exopolymeric matrix were evaluated using the phenol-sulfuric method and the data was expressed in µg of polysaccharide/mg of dry weight biofilm. Colony-forming units (CFU) were counted on Sabouraud Dextrose agar. Metabolic activity of biofilms was measured using XTT reduction colorimetric assay (490 nm). The data was analyzed by Student’s t test with 5% significant level.

Results: All experimental biofilms showed lower amounts of soluble extracellular, insoluble extracellular and intracellular polysaccharides (P<0.05). Colony-forming units (CFU) was also reduced (p<0.05). The exposure to FLZ significantly decreased the metabolic activity of the biofilms for all strains evaluated (p<0.05). The proportion of exopolymeric matrix/CFU indicates an increase in exopolymeric matrix in experimental group.

Conclusion: It can be concluded that there is an increase to exopolymeric matrix of Candida albicans biofilms in the presence of fluconazole.