Amphotericin B (AMB) and voriconazole (VOR) effect the fungal membrane ergosterol, and caspogungin (CAS) effects on the cell wall 1,3-β -D-glucan. C.krusei is inherent resistant to fluconazole and hence it is an important problem especially for immunocompromised patients. Thus we evaluated the postantifungal effect (PAFE) of these three antifungals against clinical C.krusei isolates.
Thirty C.krusei isolates from various clinical samples were included in this study. Minimal inhibitory concentration (MIC) values of three antifungals were determined by reference CLSI M27-A2 broth microdilution methods. The PAFE tests were performed at 1/4x MIC, 1x MIC and 4x MIC for all isolates. Following the exposure period of 1 h, antifungal was removed by three sequential centrifugations. The fungal pellet was resuspended with RPMI 1640 medium after the final centrifugation and plated on potato dextrose agar at 0, 2, 6, 12, 24, and 48 h of incubation for colony counting.
VOR did not display any measurable PAFE, AMB and CAS exhibited dose-dependent PAFE for all isolates. PAFE values ranged 7-43 h at 1/4xMIC, 20->43 h at 1xMIC, 30->44 h at 4xMIC for AMB and 12->45 h at 1/4xMIC, 10->45 h at 1xMIC, 20-45 h at 4xMIC for CAS. In addition, AMB and CAS caused the large reductions in colony counts that persisted during the testing period.
VOR had no measurable PAFE, whereas AMB and CAS demonstrated a significant dose-dependent PAFE against C.krusei isolates tested. The longest PAFEs were observed with CAS in general.
Full conference title:
- ASM 111th (2011)