Genomic Insights into Fluconazole Resistance in Candidozyma auris Clade II: Comparative SNP-Based Analysis of South Ko-rean Isolates

Candidozyma auris (formerly Candida auris) is an emerging multi-drug-resistant fungal pathogen with confirmed cases in over 30 countries. Although whole genome sequencing (WGS) analysis defined distinct clades during characterization of underlying genetic mechanism behind multi-drug resistance, clade II remains under evaluated. In this study, thirty-nine clade II C. auris clinical isolates and thirteen reference strains were analyzed using WGS-based single-nucleotide polymorphism analysis for confirmation of clade II classification (mating type locus analysis) and for investigation of fluconazole resistance mechanism. Antifungal susceptibility testing indicate that 46% of clinical isolates were fluconazole resistant. Phylogenetic analysis identified a distinct clade of fluconazole resistant mutants, including six clinical isolates and three reference strains (MIC >= 128 ug/mL). Eleven mutations were identified in key proteins involved in cell membrane dynamics (TAC1B, YOR1, PMA1, GPI1, VPS53, SEC28, EXO70) and metabolic stress response (PCK1, AMD21/AMD22, NIC96, CAN2), which could have indirect supporting role in fluconazole resistance. Except for TAC1B, the mutations were associated with fluconazole resistance in C. auris for the first time. Their function were inferred from orthologous functions in other Candida sp. and/or Saccharomyces cerevisiae. While this study provides deeper genomic context further functional validation is required to investigate direct relationship behind fluconazole resistance in C. auris.