Fluconazole impacts the extracellular matrix of fluconazole-susceptible and -resistant and biofilms.

: Fluconazole (FLZ) is a drug commonly used for the treatment of infections. However, β-glucans in the extracellular matrices (ECMs) hinder FLZ penetration into biofilms, while extracellular DNA (eDNA) contributes to the biofilm architecture and resistance. : This study characterized biofilms of FLZ-sensitive (S) and -resistant (R) and in the presence or absence of FLZ focusing on the ECM traits. Biofilms of American Type Culture Collection (ATCC) 90028 (CaS), ATCC 96901 (CaR), ATCC 2001 (CgS), and ATCC 200918 (CgR) were grown in RPMI medium with or without FLZ at 5× the minimum inhibitory concentration (37°C/48 h). Biofilms were assessed by colony-forming unit (CFU)/mL, biomass, and ECM components (alkali-soluble polysaccharides [ASP], water-soluble polysaccharides [WSP], eDNA, and proteins). Scanning electron microscopy (SEM) was also performed. Data were analyzed by parametric and nonparametric tests (  =  0.05). : In biofilms, FLZ reduced the CFU/mL of all strains ( < 0.001), except for CaS ( = 0.937). However, the ASP quantity in CaS was significantly reduced by FLZ ( = 0.034), while the drug had no effect on the ASP levels in other strains ( > 0.05). Total biomasses and WSP were significantly reduced by FLZ in the ECM of all yeasts ( < 0.001), but levels of eDNA and proteins were unaffected ( > 0.05). FLZ affected the cell morphology and biofilm structure by hindering hyphae formation in CaS and CaR biofilms, by decreasing the number of cells in CgS and CgR biofilms, and by yielding sparsely spaced cell agglomerates on the substrate. : FLZ impacts biofilms of and as evident by reduced biomass. This reduced biomass coincided with lowered cell numbers and quantity of WSPs. Hyphal production by was also reduced.