In Vitro Susceptibilities to Caspofungin and Micafungin of Clinical Isolates of Candida Species

Abstract

Caspofungin and micafungin are echinochandins with potent activities against Candida species. However, in vitro susceptibility to these agents of clinical Candida isolates in Korea has not been fully surveyed. We determined minimum inhibitory concentrations (MICs) of caspofungin and micafungin against clinical isolates of Candida species. A total of 107 blood isolates of Candida species (24 C. albicans, 25 C. tropicalis, 24 C. glabrata, 20 C. parapsilosis, 8 C. krusei, and 6 other Candida species) were tested by using the National Committee for Clinical Laboratory Standards M27-A2 broth microdilution methods. The in vitro antifungal activities and spectrum of caspofungin and micafungin were compared with those of amphotericin B, fluconazole, and itraconazole. Caspofungin and micafungin exhibited a broad-spectrum activity against Candida species: caspofungin MIC ranged from 0.125 to 1 microg/mL and micafungin MIC from </=0.03 to 1 microg/mL. C. albicans, C. tropicalis and C. glabrata showed high susceptibility to caspofungin (MIC(90), 0.25 to 0.5 microg/mL) and micafungin (MIC(90), </=0.03 microg/mL), whereas C. parapsilosis was less susceptible to both echinocandins (MIC(90), 1 microg/mL). The MIC(50) for caspofungin, micafungin, amphotericin B, fluconazole, and itraconazole were 0.25, </=0.03, 0.5, 1, and 0.125 microg/mL, respectively. Caspofungin MIC(50) of C. glabrata and C. krusei isolates with decreased susceptibility to azoles were 0.25 and 0.5 microg/mL, respectively, and micafungin MIC(50) were </=0.03 and 0.125 microg/mL, respectively. These data showed an excellent in vitro activity of caspofungin and micafungin against clinical strains of Candida species, including isolates with reduced susceptibility to azoles.