Fluconazole and echinocandin resistance of Candida species in invasive candidiasis at a university hospital during pre-COVID and the COVID outbreak

Abstract

Antifungal susceptibility of Candida species is decreasing. Successful treatment for antifungal-resistant candida infection is challenging and associated with significant mortality. We performed a prospective observational study to identify the species and antifungal susceptibilities of invasive isolates of Candida species over a five-year period at a university hospital in southern Thailand. Identification of Candida species was confirmed by MALDI-TOF and sequencing. Susceptibility testing was performed using a broth microdilution panel with susceptibility interpretation using breakpoints from the Clinical Laboratory Standards Institute. Between 2017 and 2021, the species distribution was 39.1% C. tropicalis, 24.8% C. albicans, 20.3% C. parapsilosis complex, 10.5% C. glabrata, and 5.2% miscellaneous Candida spp. Notable observations include elevated MIC and decrease susceptibility of C. tropicalis and C. glabrata to echinocandin and all tested triazoles. A shift of MIC90 value in the COVID era was seen in C. albicans and C. tropicalis with azoles and echinocandins. Azole resistance increased among C. tropicalis isolates, and echinocandin resistance also increased among C. parapsilosis and C. glabrata isolates. Novel alterations in FKS1 HS1 and HS2 were detected in both isolates of anidulafungin-resistant C. parapsilosis. As Candida species have become more resistant to azoles and less susceptible to echinocandin development, the need arose to observe the emergence of resistance to both antifungal classes in candida clinical isolates, for a more effective infection control in the hospital.