Species Distribution and Antifungal Susceptibility of Fungal Blood Isolates over a 16-Year Period at a University Hospital

Abstract

This study aimed to investigate the species distribution and antifungal susceptibility of fungal blood isolates collected at a university hospital between 2008 and 2023. A total of 395 fungal isolates were identified, with Candida albicans being the most prevalent species (46.1%), followed by Candida parapsilosis (23.5%), Candida glabrata (13.7%), and Candida tropicalis (6.3%). Antifungal susceptibility to three azoles and micafungin was assessed using the Clinical and Laboratory Standards Institute guidelines, M27-A3 (2008) and M27M44S ED3 (2022). Susceptibility categorization was defined as susceptible (S) or susceptible-dose-dependent (SDD). The findings revealed high susceptibility rates for C. albicans, C. glabrata, and C. parapsilosis to fluconazole, itraconazole, and voriconazole under the 2008 criteria (S + SDD = 89.5%–100%). In contrast, according to the 2022 criteria, C. albicans and C. parapsilosis exhibited 100% susceptibilities to fluconazole and voriconazole, whereas C. glabrata was only susceptible to fluconazole at the SDD (97.4%). Susceptibility of C. tropicalis to the tested azoles was notably lower, with rates of S + SDD = 52.4% under the 2008 criteria and S + SDD = 47.3% and 52.4% for fluconazole and voriconazole, respectively, under the 2022 criteria. Susceptibility to micafungin was high in all four common Candida species, with rates of S ≥ 97.4% under the 2008 criteria and S ≥ 94.7% under the 2022 criteria. These results indicate that antifungal susceptibility among fungal blood isolates has remained stable, except decreasing susceptibility of C. tropicalis to azoles. Continuous surveillance is essential to inform the optimization of treatment strategies for invasive fungal infections.