Caspofungin

The procedures of broth microdilution method and XTT analysis were referenced previously with a few modifications (Ramage et al., 2001 (link)). The initial concentration was 5 × 10⁴ CFU/mL for Candida single and mixed biofilm formations. The stock solution of caspofungin (Yuanye, Shanghai, China) was prepared by direct dissolving the drug into RPMI-1640 (pH 7.0) to the concentration of 100 μg/mL. To test sessile minimum inhibitory concentration (SMIC), the caspofungin storage underwent a series of twofold dilution. If the end-point appeared between two dilutions, a further dilution will performed till the change between two concentrations was 0.05 μg/mL. The SMIC₈₀ was defined as the drug concentration that inhibited 80% of fungal biofilms by comparing the metabolic activity with that of drug-free control at 492 nm using XTT (Sangon, Shanghai, China) method.