The Inhibition of Yeast-to-Hypha Conversion Induced by Amphotericin B in Candida albicans Is Dependent on Its Antifungal Effect

J. Argüelles

Author address: 

Univ. de Murcia, Murcia, Spain


The morphological transition from yeast to hypha is considered a factor of virulence in the opportunistic pathogenic fungus Candida albicans (Gow et al., 2002). It has been proposed that sub-lethal concentrations of Amphotericin B (AMB) induce a complete suppression of the capacity to issue germ-tubes, which is the first step of dimorphic conversion in C. albicans. Here, we have investigated the in vitro correlation between the fungicidal effect of AMB and its hypothetical inhibitory action on hypha formation in the C. albicans wild-type strain CEY.1 (CAI.4-URA+). For germ-tube induction, fresh cultures were supplemented with sterile human serum (10%) and simultaneously transferred from 28 to 37ºC. AMB concentrations below or around the MIC90 (0.12 mg/L) added to exponential CEY.1 cells caused a weak reduction in the percentage of human serum-induced germ-tube formation at 37ºC compared with an untreated control (Guirao-Abad et al., 2015). However, the dimorphic transition was drastically suppressed after addition of potentially lethal doses of AMB, which also brought about a severe degree of cell killing. These actions on cell growth and hypha formation are reversible, conditioned to the presence of the antifungal in the culture medium. In contrast, an identical experimental approach carried out with the fungistatic compound 5-fluorocytosine had no significant effect on the level of the germ-tube formation. Together, these results strongly point to a close correlation between the fungicidal action of AMB and its ability to impair morphogenetic conversion in C. albicans. This relationship might be relevant for therapeutical purposes, particularly in the light of the ability of C. albicans to develop biofilms as a main pathogenesis mechanism.

abstract No: 


Full conference title: 

ASM Microbe 2016
    • ASM microbe 1st (2016)