Farnesol Effects On Fluconazole Resistance In Candida Albicans Biofilm

Objective:To investigate the ability of farnesol to enhance biofilm fluconazole susceptibility and make the mechanism clear.Methods:Biofilm formed at different periods (6h,12h,24h and36h) were separated into SC5314with farnesol-treated. SC5314without farnesol-treated、 fluconazole-resistance strains with farnesol-treated and fluconazole-resistance strains without farnesol-treated. XTT method was used to analyze inhibition rate of different concentrations of farnesol and the biofilm MIC. Morphology changes of candida albicans biofilm were observed by Scanning Electron Microscopy (SEM).Thickness of biofilm was observed by laser confocal microscope. Ergosterol contents were compared using High Performance Liquid Chromatography (HPLC).Results:Experiment1:With concentration of farnesol increasing, the inhibition rate of SC5314with farnesol-treated and fluconazole-resistance strains with farnesol-treated declined at6h and12h. The inhibition rate of SC5314with farnesol-treated and fluconazole-resistance strains with farnesol-treated did not rise on a large scale when the concentration of farnesol was0-150μM at24h.The inhibition rate of SC5314with farnesol-treated didn’t change significantly at any time when the concentration of farnesol was50μM.The inhibition rate of SC5314with farnesol-treated declined with time going when the concentration of farnesol was100、150、200、250、300μM.The inhibition effect of farnesol to fluconazole-resistance strains was weaker than SC5314. Experiment2:The result of biofilm MIC suggested that farnesol decreased the biofilm SMIC80of SC5314without farnesol-treated at6h、12h、24h and36h.However, farnesol decreased the biofilm SMIC80of fluconazole-resistance strains without farnesol-treated at6h.12h、24h. The biofilm SMIC80of fluconazole-resistance strains without farnesol-treated was not significantly changed at36h. The biofilm SMIC80of fluconazole-resistance strains without farnesol-treated was higher than that ofSC5314without famesol-treated at6h、12h、24h and36h.Experiment3:The result of scanning electron microscopy indicate that the farnesol-treated biofilm showed thinner and latter hypha at6h、12h and24h. Farnesol made the surface of candida albicans become shrunken and sunken, these morphological changes became not so obvious with time prolonging.The matriex of fluconazole-resistance strains without farnesol-treated was more than the matriex of SC5314without farnesol-treated. The treatment of farnesol make the biofilm thinner at6h、12h and24h. The biofilm of fluconazole-resistance strains without farnesol-treated was thicker than that of SC5314without farnesol-treated at6h and12h.Experiment4:Ergosterol decreased after the treatment of farnesol at6h、12h and24h. Ergosterol of fluconazole-resistance strains without farnesol-treated was higher than that of SC5314without farnesol-treated. Ergosterol of SC5314without farnesol-treated went up with maturation of biofilm. Ergosterol of SC5314with farnesol-treated rised at6-24h and decreased at24-36h. Ergosterol of fluconazole-resistance strains with famesol-treated decreased at6-24h and rised at24-36h. Conclusions:Experiment1:Farnesol inhibit biofilm formation of candida albicans in early and middle biofilm phase.The inhibition effect strengthened with the concentration of farnesol going up.Farnesol couldn’t inhibit biofilm formation of candida albicans of mature biofilm. The inhibition effect of farnesol to Candida albicans biofilm went down with time prolonging.Experiment2:Farnesol can inhibit the drug resistance of Candida albicans biofilm.This effect is obvious in early and middle biofilm phase but not so obvious in mature biofilm phase.Experiment3:Farnesol can inhibit the formation of extracellular matrix, break the surface of candida albicans, inhibit the formation and elongation of hyphae,suppress the formation of biofilm and make the biofilm thinner.Experiment4:Ergosterol content was positively correlated with drug resistance. Farnesol can reduce the ergosterol content in the early and middle biofilm phase. The possible mechanism is that farnesol reduced ergosterol content, decreased the stability of the cell membrane and changed the permeability of azoles.