In vitro efficacy of amphotericin B, 5-fluorocytosine, fluconazole, voriconazole and posaconazole against Candida dubliniensis isolates using time-kill methodology.

Candida dubliniensis is a recently described yeast that causes infections in mucosal surfaces as well as sterile body sites. Candida dubliniensis develops resistance to fluconazole (FLC) more rapidly than the closely related species C. albicans. The killing activity of amphotericin B (AMB), 5-fluorocytosine (5FC), FLC, voriconazole (VRC) and posaconazole (POS) was determined against six C. dubliniensis clinical isolates, identified using molecular biological methods and C. dubliniensis CD36 reference strain. Minimum inhibitory concentrations (MICs) were determined using the Clinical and Laboratory Standards Institute standard procedure. Time-kill assays were performed using RPMI-1640 as test media over a 48-h period. AMB proved to be fungicidal at >or=0.5 microg ml(-1) against all clinical isolates after 48 h. 5FC was only fungicidal at 32-64x MIC (4-8 microg ml(-1)) against all C. dubliniensis isolates. FLC, VRC and POS were fungistatic; decrease in colony number was observed only at the highest concentrations tested (8, 4 and 4 microg ml(-1), respectively). Triazoles invariably showed fungistatic effect at concentrations attainable in the serum. In clinical situations when a fungicidal antifungal is desirable, AMB may be used.