Identification of Candida glabrata complex strains isolated from clinical specimens at the species level by molecular methods and determination of their susceptibilities to antifungals.

Abstract

Candida glabrata can exhibit resistance or reduced susceptibility to fluconazole, and there is an increasing frequency of resistance to echinocandins. Candida nivariensis and Candida bracarensis, newly described in 2005 and 2006, respectively, belong to the C. glabrata complex along with C. glabrata sensu stricto. C. nivariensis and C. bracarensis have been shown to exhibit higher resistance and virulence compared to C. glabrata sensu stricto. These three species cannot be reliably distinguished based on phenotypic characteristics or biochemical-based identification systems. In this study, 40 strains initially identified as C. glabrata using biochemical-based systems were re-identified to the species level through ITS region sequencing. Antifungal susceptibility testing was conducted using the Sensititre YeastOne susceptibility panel. All strains were identified as C. glabrata sensu stricto and showed dose-dependent susceptibility to fluconazole. Of the 40 strains, 39 (97.5%) were susceptible to caspofungin, anidulafungin, and micafungin, while one (2.5%) was resistant. Further research is needed on the epidemiology, virulence factors, and resistance profiles of C. nivariensis and C. bracarensis. Accurate species-level identification and antifungal susceptibility testing of C. glabrata complex isolates are significant.