High azole non-wild type rates and nosocomial microsatellite typing aggregation of Wickerhamomyces anomalus in China according to a 12-year multicenter surveillance study.

Objectives: To investigate the epidemiology and molecular typing of 307 clinical Wickerhamomyces anomalus isolates collected in China.

Methods: A total of 307 W. anomalus isolates were collected from CHIF-NET, a surveillance network with nationwide coverage, from 2009 to 2021. Antifungal susceptibility of all W. anomalus isolates were tested by broth microdilution according to CLSI methods. Genotyping of all isolates was performed using a panel of polymorphic microsatellite markers.

Results: The number of W. anomalus isolates was highest in Northeast China, with 121 strains, accounting for 4.6% of the total Candida spp. isolates in the region. Newborns emerged as the primary community of infection, with 84 isolates (12.7% of all Candida spp. in the newborn group). Most W. anomalus isolates were recovered from blood samples (249 isolates). The isolates were found to exhibit notable ratios of non-wild type to fluconazole and voriconazole (48.5% and 34.5%). A total of 118 microsatellite-based types were identified among a set of 309 isolates that included the 307 clinical isolates along with reference strains ATCC 8168 and CICC 32553. This analysis revealed potential nosocomial outbreaks.

Conclusions: Our research is the largest investigation of W. anomalus drug susceptibility thus far, providing foundational data that could contribute to future establishment of resistance breakpoints and enhancing epidemiological surveillance capabilities. Our study suggests the importance of nosocomial surveillance and drug resistance management for W. anomalus.