Exponential Clonal Expansion of 5-Fluorocytosine-Resistant Candida tropicalis and New Insights into Underlying Molecular Mechanisms.

ABSTRACT: In 2022, we initiated systematic 5-fluorocytosine susceptibility testing of Candida spp. isolates in Denmark; we observed a bimodal MIC distribution in C. tropicalis, with MICs >16 mg/L in half the isolates. This study investigates the epidemiology and molecular mechanisms of 5-fluorocytosine resistance in C. tropicalis. We analyzed 104 C. tropicalis isolates from 3 time periods, alongside 353 C. albicans and 227 C. glabrata isolates from 2022. We determined MICs using EUCAST E.Def 7.3. Sequencing of FCY2 (purine-cytosine permease), FCY1 (cytosine deaminase), FUR1 (uracil phosphoribosyl transferase), and URA3 (orotidine-5'-phosphate decarboxylase) genes revealed FCY2 alterations-E49X (30/32), Q7X (1/32), and K6NfsX10 (1/32)-in resistant C. tropicalis strains. We found a URA3 alteration, K1

SUBMITTER: Abou-Chakra N 

PROVIDER: S-EPMC12044241 | biostudies-literature | 2025 May

REPOSITORIES: biostudies-literature