Molecular Mechanism of Flucytosine Resistance in Candida lusitaniae : Contribution of the FCY2 , FCY1 , and FUR1 Genes to 5-Fluorouracil and Fluconazole Cross-Resistance

Abstract
Inactivation of the FCY2 (cytosine permease), FCY1 (cytosine deaminase), and FUR1 (uracil phosphoribosyltransferase) genes in Candida lusitaniae produced two patterns of resistance to flucytosine. Mutant fur1 demonstrated resistance to 5-fluorouracil, whereas mutants fcy1 and fcy2 demonstrated fluconazole resistance in the presence of subinhibitory flucytosine concentrations.