Resistance rates of non-albicans Candida infections in Taiwan after the revision of 2012 Clinical and Laboratory Standards Institute breakpoints

Abstract

Purpose: In 2012, the Clinical and Laboratory Standards Institute (CLSI) revised its breakpoints for drugs and species because of the increase in non-albicans Candida infections and their drug resistance. Following global trends, the non-albicans candidemia resistance rate has increased in Taiwan as well. To update the antifungal susceptibility of non-albicans candidemia isolates, we conducted a multicenter study using the revised break points. Patients and methods: Patients with non-albicans candidemia infections were identified at five tertiary hospitals in Taiwan from July 1, 2011, to June 30, 2014. The broth microdilution method using a Sensititre YeastOne system was performed for the determination of minimum inhibitory concentration (MIC). The susceptibility was interpreted based on the guidelines of the CLSI (CLSI M27-S4 and M27-S3). Results: Candida tropicalis was the predominant non-albicans candidemia pathogen (42.4%), and it showed increased fluconazole non-susceptibility (36.3%) when compared to the results from previous studies. In particular, C. tropicalis showed high cross-resistance to azole agents. C. tropicalis isolates that were found to be resistant to fluconazole also showed increased resistance to voriconazole (82.2%) and posaconazole (100%). The increased non-susceptibility of Candida glabrata to multiple antifungal agents, based on the revised break points, resulted from an increase in dose-dependent susceptibility (94.4%) rather than from an increase in resistance (5.6%). Conclusion: The resistance rate of non-albicans candidemia isolates is increasing, particularly for C. tropicalis and C. glabrata.