Efficacy of Lamiaceae essential oils with selected azoles against Candida albicans clinical isolates

A current problem in candidiasis treatment is increasing resistance to azoles, which are often prescribed to patients. The study underlines the high resistance of yeasts to fluconazole, which achieved high MIC (minimal inhibitory concentration) values both alone and in combination with essential oils (EOs). Antifungal activity of Hyssopus officinalis, Thymus vulgaris, Salvia officinalis and Rosmarinus officinalis EOs was determined against 13 clinical isolates of Candida albicans and reference strain Candida albicans ATCC 10231. The synergistic effect was investigated for the combination of itraconazole and fluconazole with Hyssopus officinalis and Thymus vulgaris EOs. Based on the fractional inhibitory concentration index, the synergistic effect was achieved in all of the samples exposed to itraconazole with Hyssopus officinalis (FICI 0.3±0.06). On the other side, the additive effect was proven in use of itraconazole with Thymus vulgaris (FICI 0.75±0.35) and fluconazole with both EOs tested (FICI 0.81±0.19; 0.88±0.57) This study shows the importance of monitoring the synergistic effect of antifungals combined with EOs, because it is a possible solution for reducing the resistance and improving the disease prognosis.