Withania somnifera seed oil exhibits antibiofilm properties against drug-resistant Candida auris clinical isolate through modulation in cell permeability

Aim: Candida auris, fast evolving drug-resistant fungus, poses an imminent global health threat. Alternative drug-resistance nonevoking treatment options are necessary. This study explored the antifungal and antibiofilm efficacies of Withania somnifera seed oil extracted using super critical CO2 (WSSO) against clinically isolated Fluconazole-resistant C. auris and its putative mode-of-action. Methods and Results: Effects of WSSO on C. auris were tested by broth microdilution method, with observed IC50 at 5.96 mg ml.1. Time-kill assay revealed that WSSO is fungistatic. Mechanistically, ergosterol binding and sorbitol protection assays showed that C. auris cell membrane and cell wall are the targets for WSSO. Lactophenol: Cotton-Blue: Trypan-Blue staining confirmed loss of intracellular contents by WSSO treatment. Candida auris biofilm formation was disrupted by WSSO (BIC50: 8.52 mg ml.1). Additionally, WSSO exhibited dose and time-dependent mature biofilm eradication property with 50% efficacies at 23.27, 19.28, 18.18, and 7.22 mg ml.1 over 24, 48, 72, and 96 h, respectively. Biofilm eradication by WSSO was further substantiated through scanning electron microscopy. Standard-of-Care Amphotericin B, at its break-point concentration, (2 μg ml.1) was found to be inefficient as an antibiofilm agent. Conclusions: WSSO is a potent antifungal agent effective against planktonic C. auris and its biofilm. Significance and Impact of Study A natural antifungal agent against drug-resistant Candida auris has been identified.