Sensititre yeastone system

All preserved, available non-albicans Candida isolates were identified by morphology analysis on CHROMagar (Creative Life Science, New Taipei City, Taiwan) and biochemical methods using a Vitek 2 system with the YST Card (bioMérieux, Durham, NC, USA). The broth microdilution method using a Sensititre YeastOne system (Trek Diagnostic Systems, East Grinstead, UK) was performed to determine the minimum inhibitory concentration (MIC) according to the manufacturer’s instructions. C. krusei ATCC 6258 and C. parapsilosis ATCC 22019 were used as quality control strains. The MICs of amphotericin B, caspofungin, micafungin, anidulafungin, fluconazole, voriconazole, itraconazole, posaconazole and flucytosine were determined, and interpretation criteria were based on the MIC breakpoints of non-albicans Candida species, as recommended by the Clinical and Laboratory Standards Institute.²²

Fungal blood cultures were processed using the BACTEC culture system (Becton Dickinson Microbiology System, Sparks, MD, USA). All non-albicans Candida isolates were identified to the species level by morphology analysis on CHROMagar (Creative Life Science, Ltd., New Taipei City, Taiwan) and biochemical methods using the API ID 32C system (bioMérieux, Marcy l’Etoile, France) or Vitek 2 system (bioMérieux, Marcy l’Etoile, France) according to the regulations of each participating hospital. The in vitro susceptibility to nine antifungal agents, including anidulafungin, caspofungin, micafungin, fluconazole, voriconazole, itraconazole, posaconazole, 5-fluocytosine, and amphotericin B, was determined using the broth microdilution method with the Sensititre YeastOne system (Trek Diagnostic Systems, Ltd., East Grinstead, UK) according to the manufacturer’s instructions. We utilized C. krusei (ATCC 6258) and C. parapsilosis (ATCC 22019) as reference isolates for quality control. The minimal inhibitory concentrations (MICs) of the nine tested antifungal agents were interpreted using the clinical breakpoints or epidemiological cut-off values proposed by the Clinical and Laboratory Standard Institute (CLSI) recommendations [26 ].

Antifungal susceptibility of all these Candida spp. isolates to eight antifungal agents was determined by a broth microdilution method, using the Sensititre YeastOne system (Trek Diagnostic Systems Ltd., East Grinstead, UK) according to the manufacturer’s instructions [23 (link),24 (link)]. Minimum inhibitory concentration (MIC) was recorded as the highest concentration of antifungal agent resulting in the development of a blue color. The criteria for susceptibility of all Candida isolates to eight antifungal agents were based on MIC breakpoints of Candida spp. recommended by the Clinical and Laboratory Standards Institute (CLSI) [25 ]. For uncommon Candida spp., other than C. guilliermondii, clinical breakpoints are undefined; therefore, isolates that showed MICs higher than the epidemiologic cutoff value were considered potentially resistant [26 (link)].