Antifungal activity of some vegetal extracts on Candida biofilms developed on inert substratum

Essential oils extracted from Citrus maxima (epicarp), Anethum graveolens (fruits) and Picea abies (leaves) were investigated for their ability to inhibit the growth and coordinated expression of virulence factors in Candida sp. strains recently isolated from clinical specimens, identified by using Vitek II automatic system and tested for susceptibility to antifungal drugs by E-test method. Plant materials were hydrodistiled in a Neo Clevenger type apparatus. Qualitative screening was performed using killing time curve and an adapted disk diffusion method. The microtiter method was used for establishing the influence of the essential oils on the microbial adherence to inert substrata. Subinhibitory concentrations of the tested essential oils were studied for their interference with the expression of soluble enzymatic virulence factors. All extracts exhibited an inhibitory activity of variable intensity on the microbial growth of planktonic as well as adherent strains, demonstrating the potential effect of the active compounds on the coordinated expression of virulence factors and consequently, on the initiation and progression of a fungal biofilm associated infection.