Antifungal Activity and Mode of Action of Miltefosine Against Clinical Isolates of Candida krusei

Abstract

Candida krusei attracts attention from medical professionals mainly for its intrinsic resistance to fluconazole and the limited number of drugs available to treat C. krusei vulvovaginal candidiasis. Miltefosine was demonstrated to have good antifungal activity both in vitro and in vivo. Here, we determined the susceptibility profiles of 57 clinical C. krusei isolates from vulvovaginal candidiasis patients and assessed the antifungal activity of miltefosine against C. krusei. All isolates were susceptible to voriconazole and itraconazole, whereas 1.8% of the isolates were of non-wild-type phenotype to amphotericin B. In contrast, miltefosine showed low MICs against all C. krusei isolates with fungicidal activity. The checkerboard assay showed that the synergistic effect of miltefosine in combination with amphotericin B was observed in 25% of the tested planktonic C. krusei isolates and 18.8% of the tested preformed biofilms, whereas miltefosine in combination with fluconazole showed indifferent interaction for all tested planktonic isolates. The presence of sorbitol in the broth microdilution assay did not influence the MIC values of miltefosine against C. krusei, but the presence of ergosterol increased the MIC values. Visible changes in cell content in cells treated with miltefosine were observed. We found that cells treated with miltefosine showed decreased cell viability and chromatin condensation under PI staining, which indicates that miltefosine may induce apoptosis-like cell death in C. krusei. In conclusion, we found miltefosine has a good activity against C. krusei isolates and exerts its fungicidal effect by binding to ergosterol in the cell membrane and inducing apoptosis.

Screening of chemical libraries for new antifungal drugs against Aspergillus fumigatus reveals the potential mechanism of action of miltefosine

“…In contrast to our results, miltefosine has been reported to have synergy with posaconazole against Fusarium oxysporum and the mucormycetes (118). In addition, a recent study with C. auris demonstrated that for 25% of the isolates assessed there was a synergic activity between miltefosine and amphothericin B, with FICI=0.5 (110).…”

“…The interaction assay between miltefosine and myriocin showed that at high concentrations of both compounds, the FICI value was greater than 4.0 characterizing an antagonistic effect between these drugs (76). This implicates that sphingolipid metabolism may be important to the antifungal effect of miltefosine, corroborating with previous results obtained for other fungal species and trypanosomatids (77,78,105,110).…”

“…Concerning to its antifungal behavior, miltefosine has demonstrated to be effective against different fungal species (100-111), however, its mode of action remains to be clarified. Recent studies have suggested that miltefosine triggers its antifungal effects by destabilizing cell membranes and inducing apoptosis (102,105,110,112,113). Accordingly, Spadari and colleagues (2018) demonstrated that for Cryptococcus spp.…”

“…miltefosine affects the plasma membrane permeability due its interaction with ergosterol and/or phospholipids increasing the production of ROS and DNA fragmentation which culminates with the fungal death by apoptosis (105). In addition, in C. krusei, the mode of action of miltefosine is also supposed to be related to the binding of the drug to ergosterol in the cell membrane leading to the cell apoptosis (110).…”

Miltefosine Against Scedosporium and Lomentospora Species: Antifungal Activity and Its Effects on Fungal Cells

“…Exogenous ergosterol addition competes with the target on the C. neoformans and Candida krusei membrane and increases the miltefosine MIC (Spadari et al, 2018;Wu et al, 2020). Because GlcCer, a sphingolipid well studied in Scedosporium and Lomentospora species, plays crucial roles in fungal growth and virulence and is a component of lipid rafts, we decided to check whether it could cause the same effect.…”