Prevalence and Antifungal Susceptibility of Pathogenic Yeasts in China: A 10-Year Retrospective Study in a Teaching Hospital

To determine the dynamic changes of pathogenic yeast prevalence and antifungal susceptibility patterns in tertiary hospitals in China, we analyzed 527 yeast isolates preserved in the Research Center for Medical Mycology at Peking University, Beijing, China, between Jan 2010 and Dec 2019 and correctly identified 19 yeast species by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and ribosomal DNA sequencing. Antifungal susceptibility testing was performed following a Sensititre YeastOne colorimetric microdilution panel with nine clinically available antifungals. The Clinical and Laboratory Standards Institute (CLSI)-approved standard M27-A3 (S4) and newly revised clinical breakpoints or species-specific and method-specific epidemiological cutoff values were used for the interpretation of susceptibility test data. In this study, althoughCandida albicanswas the predominant single species, non-C. albicansspecies constituted >50% of isolates in 6 out of 10 years, and more rare species were present in the recent 5 years. The non-C. albicansspecies identified most frequently wereCandida parapsilosis sensu stricto,Candida tropicalis, andCandida glabrata. The prevalence of fluconazole and voriconazole resistance in theC. parapsilosis sensu strictopopulation was <3%, butC. tropicalisexhibited decreased susceptibility to fluconazole (42, 57.5%) and voriconazole (31, 42.5%), and 22 (30.1%)C. tropicalisisolates exhibited wild-type minimum inhibitory concentrations (MICs) to posaconazole. Furthermore, fluconazole and voriconazole cross-resistance prevalence inC. tropicaliswas 19 (26.1%). The overall prevalence of fluconazole resistance in theC. glabratapopulation was 14 (26.9%), and prevalence of isolates exhibiting voriconazole non-wild-type MICs was 33 (63.5%). High-level echinocandin resistance was mainly observed inC. glabrata, and the prevalence rates of isolate resistance to anidulafungin, micafungin, and caspofungin were 5 (9.6%), 5 (9.6%), and 4 (7.7%), respectively. Moreover, oneC. glabrataisolate showed multidrug resistant to azoles, echinocandins, and flucytosine. Overall, the 10-year surveillance study showed the increasing prevalence of non-C. albicansspecies over time; the emergence of azole resistance inC. tropicalisand multidrug resistance inC. glabrataover the years reinforced the need for epidemiological surveillance and monitoring.