Echinocandin Resistance in Candida auris Occurs in the Murine Gastrointestinal Tract Due to <i>FKS1</i> Mutations

Abstract

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