The effect of subinhibitory concentrations of gentian violet on the germ tube formation by Candida albicans and its adherence to oral epithelial cells

Objective: This study investigated the effect of subinhibitory concentrations of gentian violet on the germ tube formation by Candida albicans and its adherence ability to oral epithelial cells. Methods: Thirty strains of C. albicans isolated from denture wearers, normal healthy individuals and HIV positive patients were used in the study. The antifungal property (Minimum Fungicidal Concentration) of gentian violet was determined at various time intervals using a microdilution technique. The effect of subinhibitory concentrations of gentian violet on the adherence ability (0.000244%) and on germ tube formation ((0.000244%, 0.000122%, 0.000061% and 0.000031%) was determined. In both experiments, water was used as a control. The test results were compared using the Kruskal-Wallis test. Results: At 60 min a high concentration (0.0078%) of gentian violet was required to completely kill C. albicans. Subinhibitory concentrations of gentian violet significantly reduced the adherence ability of C. albicans by 57% (p < 0.01) and equally inhibited germ tube formation (p < 0.01) compared with the controls. The inhibition was concentration dependent, with up to 98% reduction at a concentration of 0.000244%. Germ tube reduction was significantly higher in the isolates from the HIV positive patients than in the isolates from denture wearers. Conclusion: At high concentrations, gentian violet killed C. albicans, whereas at subinhibitory concentrations it reduced its virulence by preventing the adherence ability and germ tube formation. This suggests that the beneficial effects of gentian violet would last beyond the fungicidal concentrations in the treatment of candidiasis.