Candidozyma auris utilizes transferrin, but not heme-bound iron for in vivo virulence

Abstract

Candidozyma auris (C. auris) is an emerging multidrug-resistant fungal pathogen, and its dissemination to the bloodstream and deep-seated organs is associated with high mortality. The limited antifungal armory and pipelines against C. auris pose a major challenge in disease management. Addressing this threat requires a deeper understanding of fungal virulence mechanisms that promote persistence and of host factors that drive susceptibility. Previous in vitro studies showed that iron enhances C. auris resistance to azoles and echinocandins, whereas iron chelation mitigates this effect. Here, we demonstrate that C. auris does not utilize cell-free heme or induce hemolysis but instead extracts and uses iron from transferrin to support growth and virulence. Deletion of the SIT1 siderophore transporter in C. auris attenuated fungal growth and reduced renal injury, while increased transferrin-iron saturation worsened disease outcomes in immunocompetent mice, highlighting the importance of transferrin-bound iron uptake. Mechanistically, C. auris exploits transferrin-bound iron to enhance ergosterol biosynthesis and activate antioxidant defenses, promoting resistance to neutrophil- and caspofungin-mediated killing. These findings identify elevated transferrin saturation as a novel host susceptibility risk factor for disseminated C. auris infection and reveal how iron availability reshapes fungal physiology to drive infection persistence.