Anidulafungin Is Fungicidal and Exerts a Variety of Postantifungal Effects against Candida albicans , C. glabrata , C. parapsilosis , and C. krusei isolates

Abstract

Anidulafungin targets the cell walls of Candida species by inhibiting ␤-1,3-glucan synthase, thereby killing isolates and exerting prolonged postantifungal effects (PAFEs). We performed time-kill and PAFE experiments on Candida albicans (n ‫؍‬ 4), C. glabrata (n ‫؍‬ 3), C. parapsilosis (n ‫؍‬ 3), and C. krusei (n ‫؍‬ 2) isolates and characterized the PAFEs in greater detail. MICs were 0.008 to 0.125 g/ml against C. albicans, C. glabrata, and C. krusei and 1.0 to 2.0 g/ml against C. parapsilosis. During time-kill experiments, anidulafungin caused significant kills at 16؋ MIC (range, log 2.68 to 3.89) and 4؋ MIC (log 1.87 to 3.19), achieving fungicidal levels (>log 3) against nine isolates. A 1-hour drug exposure during PAFE experiments resulted in kills ranging from log 1.55 to 3.47 and log 1.18 to 2.89 (16؋ and 4؋ MIC, respectively), achieving fungicidal levels against four isolates. Regrowth of all 12 isolates was inhibited for >12 h after drug washout. Isolates of each species collected 8 h after a 1-hour exposure to anidulafungin (16؋ and 4؋ MIC) were hypersusceptible to sodium dodecyl sulfate (0.01 to 0.04%) and calcofluor white (40 g/ml). Moreover, PAFEs were associated with major cell wall disturbances, as evident in electron micrographs of viable cells, and significant reductions in adherence to buccal epithelial cells (P < 0.01). Finally, three of four PAFE isolates tested were hypersusceptible to killing by J774 macrophages (P < 0.007). Our data suggest that the efficacy of anidulafungin in the treatment of candidiasis might stem from both direct fungicidal activity and indirect PAFEs that lessen the ability of Candida cells to establish invasive disease and to persist within infected hosts.

Killing Rates for Caspofungin Against Candida albicans After Brief and Continuous Caspofungin Exposure in the Presence and Absence of Serum

“…Killing 23 rates (k values) in time-kill and PAFE experiments 24 were determined for each strain and concentration. In 25 time-kill experiments, colony count decreases were 26 isolate-and concentration-dependent at 0.25, 1,4,8,27 16 and 32 mg/L in RPMI-1640, but concentration-28 independent at 1,4,8,16 …”

“…In case of isolate DPL20, we used 4, 8, 103 16 and 32 mg/L caspofungin. Otherwise, the method 104 was the same as described for PAFE [3][4][5]. All 105 experiments were performed at least twice, and means 106 of data are presented.…”

“…99 For time-kill assays (continuous 24-h caspofungin 100 exposure), test solutions were not centrifuged or 101 washed. We used 0.25, 1,4,8,16 and 32 mg/L 102 caspofungin. In case of isolate DPL20, we used 4, 8, 103 16 and 32 mg/L caspofungin.…”

“…ATCC 10231 and an echinocandin-resistant 66 isolate (DPL20, FKS F645P) were also included in 67 the study. 5 cells/ml [3][4][5]. After 1 h, the cells were 92 collected by centrifugation at 1.5009g for 10 min and 93 were washed three times with sterile saline, resus-94 pended in 10 ml drug-free warm RPMI-1640 with and 95 without 50 % human serum.…”

“…After 1 h, the cells were 92 collected by centrifugation at 1.5009g for 10 min and 93 were washed three times with sterile saline, resus-94 pended in 10 ml drug-free warm RPMI-1640 with and 95 without 50 % human serum. Samples (100 ll) were 96 removed at 0, 4, 8, 12 and 24 h, serially diluted 97 tenfold, plated (4 9 30 ll) onto Sabouraud dextrose 98 agar and incubated at 35°C for 48 h [3][4][5]. 99 For time-kill assays (continuous 24-h caspofungin 100 exposure), test solutions were not centrifuged or 101 washed.…”