Micafungin

Micafungin (Astellas Pharma US, Inc., Deerfield, IL, USA) was provided as a sterile powder and was reconstituted and diluted further in sterile 0.9% normal saline to achieve the required concentrations of 1 mg/mL or 10 mg/mL.
The dosage of systemically administered Micafungin was based upon prior laboratory investigations and preliminary data for these experiments [29 (link),30 (link),31 (link),32 (link)]. The concentrations for lock therapy were derived from previous in vitro studies conducted in our laboratory [17 (link),18 (link)].
The minimal inhibitory concentrations (MICs) of Micafungin were determined by standard methods of the Clinical and Laboratory Standards Institute (CLSI) using broth microdilution [37 ] and were defined as the lowest concentration that caused an optically clear well. The MICs of Micafungin against C. albicans and C. parapsilosis were 0.125 μg/mL and 0.125 μg/mL, respectively.

The echinocandins used in this study were generous gifts from Pfizer, New York, NY, USA (anidulafungin), Merck Sharp and Dohme, Kenilworth, NJ, USA (caspofungin), and Astellas Pharma, Chūō, Tokyo, Japan (micafungin). The echinocandins were kept at −20 °C in stock solution (10 mg/mL in DMSO) and assayed at the final concentrations specified in the text, tables, and figures. For micro-culture assays of a large number of samples, log-phase cultures grown in YES medium were diluted to a cell density of 5 × 10⁵ cells/mL (lower cell density) or 5 × 10⁶ cells/mL (higher cell density) in YES medium containing increasing concentrations of echinocandins (1, 2, 4, 10, 20, 40, and 80 µg/mL) or an equal volume of solvent (0.8% DMSO), which was the control cell culture. The cell cultures were grown in an orbital roller at 28 °C, and turbidity was examined after 24 h of growth. The MIC was the minimal concentration of echinocandin that induced a complete inhibition of the cell growth after 24 h of growth. The values were calculated from at least three independent experiments.