Antifungal Susceptibility of Candida Albicans Biofilms on Titanium Discs

Little information is available on the formation of biofilms on implant surfaces with different surface roughness and their resistance to conventional antimicrobial therapy is unclear. Objective: To determine the effect of increasing the surface roughness of titanium discs on the susceptibility of Candida albicans biofilms to amphotericin B and to compare with that of planktonic C. albicans. Methods: Grade I commercially pure titanium (CP-Ti) rods were cut into small discs (12 mm in diameter and 1 mm in thickness) and the discs were equally divided into three groups; Group A, B and C, which were sandblasted with 99.6% aluminum oxide with mean grit size of 25 µm, 110 µm and 250 µm, respectively. The minimum inhibitory concentration (MIC) of C. albicans biofilm grown on different Ti discs was determined using XTT assay and was determined as the lowest concentration of amphotericin B with no visible color change. To determine the MIC of the planktonic cells, a modified method of the NCCLS (M27-A), the reference method for broth dilution antifungal susceptibility testing yeast, was employed. Instead of measuring turbidity, the MIC was determined using XTT assay. The experimental protocol was repeated on three occasions. Results: The mean surface roughness (Ra) of Group A, B and C was found to be 0.90, 1.88 and 3.82 µm, respectively with significant differences between groups (p<0.001). The MIC of the planktonic C. albicans (0.5 µg/mL) was much lower than those from Group A, B and C, which were 8, 32 and 8 µg/mL, respectively. Conclusions: The MICs of C. albicans biofilms formed on CP-Ti discs were higher than their planktonic counterpart and there appeared to be a optimal surface roughness of the titanium disc which allowed more effective antifungal activity.