RESEARCH ARTICLE Antifungal Susceptibilities of Bloodstream Isolates of Candida Species from Nine Hospitals in Korea: Application of New Antifungal Breakpoints and Relationship to Antifungal Usage

We applied the new clinical breakpoints (CBPs) of the Clinical and Laboratory Standards Insti-tute (CLSI) to a multicenter study to determine the antifungal susceptibility of bloodstream in-fection (BSI) isolates ofCandida species in Korea, and determined the relationship between the frequency of antifungal-resistantCandida BSI isolates and antifungal use at hospitals. Four hundred and fifty BSI isolates ofCandida species were collected over a 1-year period in 2011 from nine hospitals. The susceptibilities of the isolates to four antifungal agents were de-termined using the CLSI M27 broth microdilution method. By applying the species-specific CBPs, non-susceptibility to fluconazole was found in 16.4 % (70/428) of isolates, comprising 2.6 % resistant and 13.8 % susceptible-dose dependent isolates. However, non-susceptibility to voriconazole, caspofungin, or micafungin was found in 0 % (0/370), 0 % (0/437), or 0.5% (2/437) of theCandida BSI isolates, respectively. Of the 450 isolates, 72 (16.0%) showed de-creased susceptibility to fluconazole [minimum inhibitory concentration (MIC)4 μg/ml]. The total usage of systemic antifungals varied considerably among the hospitals, ranging from 190.0 to 7.7 defined daily dose per 1,000 patient days, and fluconazole was the most com