Antifungal Activity of Essential Oils Against Candida Species Isolated from Clinical Samples

We evaluated the in vitro antifungal activity of essential oils obtained from the aromatic plants Laurus nobilis , Thymus vulgaris , Mentha piperita , Cymbopogon citratus and Lippia junelliana against the following Candida species isolated from clinical samples: C. krusei ( n = 10); C. albicans ( n = 50); C. glabrata ( n = 70) and C. parapsilosis ( n = 80). The minimal inhibitory concentration (MIC) was determined according to EDef 7.3.1 document from EUCAST. Amphotericin B and fluconazole were the antifungal drugs used as inhibition control. The concentration ranges evaluated were 0.4–800 and 0.03–128 mg l −1 for essential oils and antifungal drugs, respectively. MIC 50 and MIC 90 , mode and ranges were calculated. All the Candida spp. evaluated were susceptible to amphotericin B (MIC ≤ 1 mg l −1 ), while fluconazole was inactive for C. krusei (MIC ≥ 32 mg l −1 ) and intermediate for C. glabrata (MIC≤ 32 mg l −1 ). The essential oils showed antifungal activity on Candida spp. tested with MIC 90 values ranging from 0.8 to 800 mg l −1 . In general, the most active essential oils were L. nobilis and T. vulgaris (MIC 90 0.8–0.16 mg l −1 ), and the least active was C. officinalis (MIC 90 400–800 mg l −1 ). C. krusei was inhibited by 5/6 of the essential oils evaluated, and C. glabrata was the least susceptible one. This in vitro study confirms the antifungal activity of these six essential oils assayed which could be a potential source of new molecules useful to control fungal infections caused by some Candida species, including those resistant to antifungal drugs.