Miltefosine as an alternative strategy in the treatment of the emerging fungus Candida auris

•Miltefosine showed fungicidal activity against clinical isolates of Candida auris (C. auris) and antibiofilm effect.•Treatment with miltefosine, in its free form and loaded-alginate nanoparticles, resulted in improvements in the larval survival and morbidity rates in the Galleria mellonella model infected by C. auris•Miltefosine formulations may be promising therapeutic alternatives to treat C. auris infection Candida auris (C. auris) is an emerging fungal species that is able to develop multidrug resistance and outbreaks of invasive infections worldwide with high mortality rates. To increase the treatment options for C. auris infection this study assessed the efficacy of miltefosine (MFS), that has demonstrated a broad-spectrum antifungal action in vitro. This study aimed to: (i) evaluate the in vitro antifungal activity of MFS against C. auris clinical isolates in the planktonic and biofilm lifestyles; and (ii) compare the activity of MFS in its free form and encapsulated in alginate nanoparticles (MFS-AN) in Galleria mellonella larvae infected by C. auris. The antifungal susceptibility test was performed using broth microdilution method and the in vivo treatment in Galleria mellonella larval infection model. MFS exhibited in vitro inhibitory effects at MICs ranging 1–4 µg/mL and fungicidal activity against planktonic cells of C. auris clinical isolates. MFS antibiofilm activity was observed during biofilm formation (0.25–4 µg/mL) and on pre-formed biofilms (16–32 µg/mL). Moreover, the dispersed cells from C. auris biofilms had a similar susceptibility to those obtained for planktonic cells. Treatment with free MFS or MFS-AN resulted in significant improvements in the survival and morbidity rates of Galleria mellonella larvae infected by C. auris. In addition, reduction of fungal burden (0.5–1 log CFU/g) and granuloma formation were observed when compared with the untreated group. The findings suggest that both the free MFS and MFS-AN have potential for the treatment of fungal infections caused by the emerging C. auris.