LAUSR

In the last two decades, with the wide use of azoles, antifungal resistance among Candida parapsilosis has considered a matter of concern worldwide. The aim of this study is to evaluate the antifungal potentials of tetrandrine (TET) alone and in combination with fluconazole (FLC)/voriconazole (VRC) against C. parapsilosis. Susceptibility tests were performed by microdilution method, checkerboard assay, time-kill test, spot assay. Subsequently, rhodamine 6G efflux test and the expressions of transporter related genes, namely CDR1 and MDR1 for C. parapsilosis were analyzed by qRT-PCR. The susceptibility test showed that TET presented strong synergism with FLC and VRC with fractional inhibitory concentration index (FICI) in a range of 0.094–0.562. The susceptibility results were also confirmed by spot assay and time-kill studies. With TET treatment, a vast quantity of rhodamine 6G could not be pumped out from the cells as considerably intracellular red fluorescence was accumulated. Meanwhile, the expressions of efflux-associated genes presented varying degrees of inhibition. These results indicated that TET was a decent antifungal synergist to promote the antifungal efficacy of FLC/VRC, and the underlying antifungal mechanism might be associated with the inhibition of efflux pump and the elevation of intracellular drug content.