Candida.

Among the millions of species in the fungal kingdom, fewer than 300 cause disease in humans, compared to the tens of thousands that cause disease in plants, insects, and ectothermic vertebrates. While the number of 'pathogenic' species is relatively small, fungal infections remain one of the leading threats to human health. Vulnerable populations with compromised immunity face the highest risk of serious infection, with over 2.5 million individuals succumbing to systemic fungal infections annually. Invasive candidiasis caused by Candida species is the leading cause of mycotic death worldwide, accounting for 88% of all hospital-acquired fungal infections in the United States. These infections are primarily caused by the fungal pathogen Candida albicans, as well as non-albicans Candida species, including emerging drug-resistant organisms such as C. auris. In fact, C. albicans and C. auris are such significant public health threats that the World Health Organization recently identified these species as 'critical threat' pathogens that are ranked highest for perceived public health importance. In this primer, we highlight some biological features of Candida species that enable them to thrive as both commensals and pathogens, including morphological diversity, genotypic plasticity, and stress response pathways required to tolerate environmental insults, with a focus on C. albicans and C. auris. We also briefly summarize current antifungal treatments used to combat Candida infections and the resistance mechanisms that have evolved to counteract these therapeutics.