Candida species are one of common opportunistic pathogens in humans. Detection of antifungal resistance between candida species become increasing, a great interest in creating new antifungals utilizing natural sources like plant essential oils (EOs) .

This study aimed to evaluate the effect of EOs of selected plants on Candida species growth, transition, and biofilm formation as well on the expression levels of certain virulence genes.

Patients and methods: Fifty candida isolates were collected from napkin dermatitis and oral candidiasis patients, different Candida species were identified phenotypically. Essential oils for some medicinal plants (basil, clove, garlic, and peppermint) were extracted by hydro-distillation. Their antifungal activity was assessed by minimal inhibitory concentration methods. In addition the effect of EOs on different Candida ultrastructure was detected by scanning electron microscope, the antibiofilm characteristics were examined by microtiter plate method. The ability of tested EOs to interfere with transition of candida from blastopore to hyphae form was evaluated. The effect of basil and clove oils on various virulent genes was determined by analyzing the expression levels of HWP, ALS3, SAP3 genes by RT-PCR.

Results: C. albicans was the most prevalent species. For all tested Candida isolates, the EOs displayed a high antifungal activity. The EOs decreased the Candida transition, disrupted the Candida ultrastructure and suppressed their ability of biofilm formation, clove oil exposure significantly downregulated the expression of HWP1, ALS3 and SAP3 genes, in addition basil oil downregulated the expression of ALS3 and SAP3.