Differential effects of antifungal agents on expression of genes related to formation of Candida albicans biofilms

In vitro and in vivo effects of suloctidil on growth and biofilm formation of the opportunistic fungus Candida albicans

As the most frequent fungal pathogen in humans, Candida albicans can develop serious drug resistance because its biofilms are resistant to most antifungal agents; this leads to an urgent need to develop novel antifungals. Here, we evaluated the efficacy of an antithrombotic drug, suloctidil, against C. albicans biofilms in vitro and in vivo. We found that suloctidil is effective to inhibit C. albicans biofilm, with a minimum inhibitory concentration (MIC₈₀) of 4 μg/mL, a biofilm inhibiting concentration (BIC₈₀) of 16 μg/mL and a biofilm eradicating concentration (BEC₈₀) of 64 μg/mL. Furthermore, the concentration-dependent characteristics of suloctidil were shown by its time-kill curves. Scanning electron microscopy images clearly revealed the morphological effects of suloctidil on biofilm. Yeast-to-hyphal form switching is a key virulence factor of C. albicans; therefore, we performed hyphal growth tests and observed that suloctidil inhibited yeast-to-hyphal form switching. This result was consistent with the down-regulation of hypha-specific gene (HWP1, ALS3, and ECE1) expression levels after suloctidil treatment. In vivo, 256 μg/mL of suloctidil significantly reduced fungal counts (P<0.01) compared to that in groups without treatment; the treatment group induced a slight histological reaction, especially when the treatment lasted for 5 days (P<0.01). Taken together, our data suggest that suloctidil is a potential antifungal agent.

Heat-Polymerized Resin Containing Dimethylaminododecyl Methacrylate Inhibits Candida albicans Biofilm

The prevalence of stomatitis, especially caused by Candida albicans, has highlighted the need of new antifungal denture materials. This study aimed to develop an antifungal heat-curing resin containing quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM), and evaluate its physical performance and antifungal properties. The discs were prepared by incorporating DMADDM into the polymer liquid of a methyl methacrylate-based, heat-polymerizing resin at 0% (control), 5%, 10%, and 20% (w/w). Flexure strength, bond quality, surface charge density, and surface roughness were measured to evaluate the physical properties of resin. The specimens were incubated with C. albicans solution in medium to form biofilms. Then Colony-Forming Units, XTT assay, and scanning electron microscope were used to evaluate antifungal effect of DMADDM-modified resin. DMADDM modified acrylic resin had no effect on the flexural strength, bond quality, and surface roughness, but it increased the surface charge density significantly. Meanwhile, this new resin inhibited the C. albicans biofilm significantly according to the XTT assay and CFU counting. The hyphae in C. albicans biofilm also reduced in DMADDM-containing groups observed by SEM. DMADDM modified acrylic resin was effective in the inhibition of C. albicans biofilm with good physical properties.