<i>Candida albicans</i> biofilm inhibition by synergistic action of terpenes and fluconazole

1032-1037The current treatment options for Candida albicans biofilm-device related infections are very scarce due to their intrinsic increased tolerance to antimycotics. The aim of this work was to study synergistic action of terpenes (eugenol, menthol and thymol) with fluconazole (FLA) on C. albicans biofilm inhibition. The minimum inhibitory concentration (MIC) assayed using CLSI M27-A3 broth micro-dilution method showed antifungal activity against C. albicans MTCC 227 at a concentration of 0.12 % (v/v) for both thymol and eugenol as compared to 0.25 % (v/v) for menthol. FLA was taken as positive control. The effect of these terpenes on metabolic activity of preformed C. albicans biofilm cells was evaluated using 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay in 96-well polystyrene microtiter plate. Thymol and eugenol were more effective at lower concentrations of ≥ 1.0 % (v/v) than menthol. Synergistic studies using checkerboard micro-dilution assay showed fractional inhibitory concentration index (Σ FIC=0.31) between thymol/FLA followed by eugenol/FLA (Σ FIC=0.37) and menthol/FLA (Σ FIC&lt;0.5) against pre-formed C. albicans biofilms. Thymol with fluconazole showed highest synergy in reduction of biofilm formation than eugenol and menthol which was not observed when their activities were observed independently. Adherence assay showed 30% viability of C. albicans cells after 2 h of treatment with 0.05 % (v/v) thymol/FLA. Effect of thymol/FLA on C. albicans adhesion visualized by SEM micrographs showed disruption in number of candidal cells and alteration in structural design of C. albicans. Thus, the study demonstrated synergistic effect of terpenes with fluconazole on C. albicans biofilm, which could be future medications for biofilm infections. </span

Impact of infectious <i style="">Candida albicans</i> biofilm on biomaterials

417-422In the present investigation, biofilm formation by Candida albicans was studied on different polymeric surfaces, viz., polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), and silicone rubber (SR). Amongst these polymeric surfaces, the maximum biofilm formation was recorded to be 64.19, 50.31, and 45.09% for PS, PP, SR, respectively in comparison to PVC after 48 h using XTT [2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)2H-tetrazolium-carboxanilide] tetrazolium reduction assay. Exopolysaccharides (EPS) production during biofilm formation, when assessed using acetone precipitation technique, was found to be 11.45, 9.41, 8.65 and 6.95 g/cm2 for PVC, PS, PP and SR, respectively. Atomic force microscopic and goniometric analysis showed maximum roughness (134 nm) and hydrophobicity (97°) for PVC. Confocal laser scanning microscopy (CLSM) studies revealed maximum biofilm thickness (117.5 µm) on PVC surface when analyzed by z-sectioning. Further, the data were confirmed by scanning electron microscopy (SEM) for biofilm growth on these biomaterials. It was observed that PVC as biomaterial is most susceptible for C. albicans biofilm formation, while material surface properties like roughness and hydrophobicity promotes C. albicans adhesion and biofilm development