Echinocandin Resistance in Candida auris Occurs in the Murine Gastrointestinal Tract Due to FKS1 Mutations

Candida auris is resistant to multiple antifungal agents. This study investigated its antifungal susceptibility and explored FKS1 mutations across the isolates from mice enterically colonized with wild-type C. auris and treated with echinocandin. Resistant C. auris with FKS1 mutations, including S639F, S639Y, D642Y, R1354H, or R1354Y, were isolated and found to be micafungin- and caspofungin-resistant in vivo; however, the MICs of isolates with mutation in R1354 remained below the micafungin breakpoint in vitro.