Inhibitory Effect of Carvacrol on the Expression of Candida albicans Hyphae-Specific Gene (HWP1)

Candida albicans infection is a problem of growing clinical importance, particularly in immunocompromised populations. This study aimed to investigate the inhibitory effect of carvacrol on the hyphae formation and expression of C. albicans HWP1. This cross-sectional study was done over a 6-month period in 2016-2017. Vaginal, mouth and skin surface swabs were obtained from immunocompromised patients. Colonizing clinical isolates of C. albicans were identified and drug susceptible isolates detected using WHONET software. The susceptibility test for carvacrol (range 6.25–300 μg/ml) were carried out with a broth microdilution according to the CLSI guidelines against drug susceptible C. albicans. The time kill assay of carvacrol (range 2 × MIC to ¼ × MIC) was determined. Hyphae inhibition was evaluated by light microscopy. We determined the expression levels of HWP1 implicated in hyphae formation of C. albicans ATCC 14053 cells by quantitative RT-PCR.
FINDINGS: Ten colonizing clinical isolates of drug susceptible C. albicans were identified. Carvacrol was inhibited the growth of all drugs susceptible isolates of C. albicans (MIC range, 25-200 µg/ml). Time kill curve assay demonstrated that carvacrol could significantly inhibit the growth of C. albicans (p≤0.05). Carvacrol efficiently prevented hyphae formation in drug susceptible C. albicans. The expression levels of HWP1 gene were down-regulated by 1.82- and 1.62-fold at concentrations of 2 × MIC and 1 × MIC of carvacrol, respectively. These results suggest that carvacrol could provide an improved and safe clinical approach in treating Candida infections by prevention of hyphae formation