Efficacy of endemic Algerian essential oils against single and mixed biofilms of Candida albicans and Candida glabrata

Objectives: This study investigated the in vitro effect of Origanum glandulosum, Ammoides verticillata, and Sacco -calyx satureioides essential oils against planktonic cells and biofilms formed by single and mixed species of Candida albicans and Candida glabrata oral isolates. The effect of the essential oils in combination with amphotericin B on planktonic cells was also studied.Design: The antifungal susceptibility of planktonic cells was evaluated by disc diffusion and broth microdilution methods. Resazurin assay and scanning electron microscopy (SEM) were employed to determine the antibiofilm activity. The combinatory effect was evaluated by the checkerboard method. Essential oils were characterized by gas chromatography-mass spectrometry (GC-MS). Results: The minimal inhibitory concentrations (MICs) and the minimum fungicidal concentrations (MFCs) of the studied essential oils were ranged between 250 and 2000 mu g/mL. Biofilms were inhibited and eradicated by the essential oils at sub-inhibitory concentrations of 500 and 1000 mu g/mL, respectively. SEM studies revealed a reduction in the preformed biofilm as a result of Origanum glandulosum essential oil treatment for single and mixed biofilms. Synergistic activity was found when Origanum glandulosum essential oil was combined with amphotericin B against Candida albicans. GC-MS analysis revealed that thymol was the major compound in Origanum glandulosum (38.36 %) and Ammoides verticillata (48.99 %) essential oils, while Saccocalyx satureioides essential oil was dominated by borneol (27.36 %).Conclusions: The studied essential oils showed significant antifungal and antibiofilm activities, which support their effectiveness as promising candidates for the management of oral Candida infections.

Automated summary

This study investigated the antifungal and antibiofilm activities of Origanum glandulosum, Ammoides verticillata, and Sacco-calyx satureioides essential oils against Candida albicans and Candida glabrata oral isolates. The essential oils showed significant activity in inhibiting and eradicating biofilms at sub-inhibitory concentrations. A synergistic effect was observed when Origanum glandulosum essential oil was combined with amphotericin B. The major compounds in the essential oils were thymol, borneol, and other components. These essential oils have potential as candidates for the management of oral Candida infections.