Chemical Composition and Antifungal Effect of the Essential Oils of Thymus vulgaris L., Origanum vulgare L., and Satureja montana L. against Clinical Isolates of Candida spp.

Abstract

Infections caused by Candida species are on the rise, and the escalating concern revolves around the growing resistance to known antifungals, particularly in immunocompromised individuals. The essential oils (EOs) of thyme, oregano, and savory were studied for antifungal, antibiofilm and potential synergistic activity against isolates of Candida. The oils underwent chemical characterization, revealing comparable compositions of the monoterpene phenols, predominantly thymol and carvacrol, albeit in varying proportions. Anti-Candida activity assessments of these EOs and the type of interactions among these agents on planktonic cells were done by microdilution and the checkerboard method, respectively. Our findings underscore the significant inhibitory effects of the tested agents against both planktonic and biofilm forms of Candida cells. The minimum inhibitory concentration (MIC) values of the tested oils against planktonic Candida cells ranged from 0.312 to 2.500 mg/mL, classifying them as highly to moderately active against the causative agents of candidosis. The effect on the formation of Candida biofilms was statistically significant for the majority of the tested candidal isolates, with a reduction percentage greater than 50%. Notably, the high significance of our study lies in the presented synergistic effects observed in the majority of the examined combinations, without any presence of antagonistic interactions.