Candida albicans and Candida glabrata clinical isolates exhibiting reduced echinocandin susceptibility

A recognized hotspot for mutations conferring reduced echinocandin susceptibility (RES) is residue S645 of Candida albicans Gsc1(Fks1). We report that the mutation F641Y is associated with RES in a C albicans isolate. The analogous Fks2 residue is mutated F to V in a Candida glabrata RES isolate; the introduction of this mutation into susceptible C glabrata confirmed its role in RES. Y641-equivalent Fks residues were identified in intrinsically RES Fusarium species and Candida guilliermondii.