Insights into the mechanism of drug resistance in Candida species

Abstract

Our study investigated the evolution of fluconazole (FLC) resistance in a drug susceptible Candida auris (C. auris) CBS10913T clade 2 isolate by exposing it to constant drug pressure, leading to the emergence of three drug-resistant replicates with varying FLC resistance levels. Each evolved replicates exhibited a unique MIC50 value, reflecting population heterogeneity. Chromosomal changes and aneuploidy are major drivers of antifungal resistance. Chr5 duplication in C. auris clade 2 was associated with FLC resistance, indicating a conserved mechanism involving genes on Chr5. In our second chapter, we highlighted the role of membrane lipids in FLC evolved resistance in C. auris. Significant changes in sphingolipid (SL) profiles were observed between both evolved resistant replicates and susceptible control, particularly in and#945;OH-GlcCer, dhCer, and PCer levels. As we noticed heterogeneity in drug resistance, these changes also observed in the SLs profile that might influence the positioning and efficiency of efflux pumps, critical for drug resistance. In our third chapter revealed the upregulation of sugar transporter genes in experimentally evolved replicates of CBS10913T and clinical FLC-resistant strains through RNA-Seq analysis and Whole-genome sequencing identified SNPs in HGTs genes. Whereas HGT7 and HGT13 genes revealed common SNPs in both clinical resistant isolates. Deleting HGT7, increased susceptibility to FLC and ITZ, while HGT13 deletion increased resistance. Both genes might be influence cell membrane integrity that effect drug susceptibility. Molecular dynamics simulations suggested high affinity of HGT7 and HGT13 for FLC, indicating their potential role in importing FLC into the cell. Overall, our study identifies multiple pathways to FLC resistance in C. auris, including aneuploidy-dependent and independent mechanisms, and underscores the complexity of lipid-mediated resistance. Further research on these pathways could offer novel therapeutic targets to combat azole resistance in C. auris.