Antifungal activity of essential oils against azole-resistant and azole-susceptible vaginal Candida glabrata strains.

Candida glabrata is an opportunistic pathogen, associated with endocarditis, meningitis, and disseminated disease, and also with complicated vaginitis. Essential oils derived from aromatic plants are known in traditional medicine as antimicrobial agents and have antifungal properties. The aim of this work was to evaluate whether 12 tested essential oils (tea tree, laurel, anise, basil, bergamot, lavender, mint, oregano, grapefruit, rosemary, winter savory, and ginger) could have a transverse effect on C. glabrata sensitive strains but above all on strains resistant to the three main azole antifungals used (clotrimazole, fluconazole, itraconazole). For this reason, different strains of C. glabrata, vaginal isolated, were characterized (disk diffusion assay, minimal inhibitory concentration) with respect to their response to such antifungals. Electron microscopy analyses were performed to examine cellular damages in depth. Subsequently, we wanted to evaluate the effect of the oils on human cells to estimate their potential cytotoxicity. Oregano and winter savory were the two most effective essential oils, inducing growth inhibition, cell damage of C. glabrata strains (both sensitive and resistant to azole antifungal drugs), and medium-high level of toxicity against human keratinocytes. The results of this work support the research for new alternatives or complementary therapies against vaginal candidiasis.

Sensitivity of Candida albicans to essential oils: are they an alternative to antifungal agents?

AIMS: Candida albicans is an important opportunistic pathogen, responsible for the majority of yeast infections in humans. Essential oils, extracted from aromatic plants, are well-known antimicrobial agents, characterized by a broad spectrum of activities, including antifungal properties. The aim of this work was to assess the sensitivity of 30 different vaginal isolated strains of C. albicans to 12 essential oils, compared to the three main used drugs (clotrimazole, fluconazole and itraconazole). METHODS AND RESULTS: Thirty strains of C. albicans were isolated from vaginal swab on CHROMagar™ Candida. The agar disc diffusion method was employed to determine the sensitivity to the essential oils. The antifungal activity of the essential oils and antifungal drugs (clotrimazole, itraconazole and fluconazole) were investigated using a microdilution method. Transmission and scanning electron microscopy analyses were performed to get a deep inside on cellular damages. Mint, basil, lavender, tea tree oil, winter savory and oregano essential oils inhibited both the growth and the activity of C. albicans more efficiently than clotrimazole. Damages induced by essential oils at the cellular level were stronger than those caused by clotrimazole. CONCLUSIONS: Candida albicans is more sensitive to different essential oils compared to the main used drugs. Moreover, the essential oil affected mainly the cell wall and the membranes of the yeast. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this work support the research for new alternatives or complementary therapies against vaginal candidiasis.