In vitro antifungal activity of essential oils from local plants against fluconazole-resistant oral Candida albicans isolates

Abstract

Background and objective: Candida albicans is an oral commensal flora that causes opportunistic local and systemic infections in immunocompromied individuals. Fluconazole is frequently used for treating patients with active infections or preventing recurrent infections. The emergence of resistant strains encouraged scientists to search for compounds that have antifungal property and can overcome the usual microbial resistant mechanisms to antimicrobial agents. Essential oils from natural plants have received great interest due to the antimicrobial property of their multiple constituents. The aim of this study was to investigate the antifungal activity of Rosemary and Thyme essential oils against fluconazole resistant oral Candida albicans isolates. Methods: Essential oil from areal parts of Rosemarium officinalis and Thymus vulgaris were obtained by hydrodistillation. Disk diffusion and microbroth dilution methods were followed to test the sensitivity of eight fluconazole resistant oral Candida albicans isolates and one ATCC strain to the extracted Essential oils. Minimum inhibitory concentration and minimum fungicidal concentration were used to evaluate the antifungal potential of the tested essential oils. Results: The results of disk diffusion method using concentrated Essential oils showed marked inhibition of growth around the prepared discs from both Essential oils. However, the recoded diameters was higher in Thyme Essential oil (Mean ± SD: 42.4 ± 6.5) when compared with Rosemary essential oil (Mean ± SD: 11.8 ± 2.8). Serial two fold dilutions of the tested essential oils showed that both essential oils attain their antifungal activities even at very low concentrations. The highest MIC and MFC of Rosemary EO were 3.125% and 6.25%, respectively. Thyme essential oil showed very low MIC and MFC (<1.56%). Conclusion: Thyme and Rosemary essential oils were ideal natural compounds against drug resistant Candida albicans strains.