Microbiological Characteristics and Drug Resistance Rates of Candida auris Isolates in Japan

Candida auris was initially isolated from a Japanese patient, and is now an emerging fungus species owing to its long-term colonization capabilities and high resistance to antifungal drugs. However, the domestic epidemiology of C. auris in Japan remains unknown. In this study, we collected C. auris isolates from hospitals, public health centers, and public health institutes in Japan based on the administrative liaison. Moreover, we also obtained isolates from three nongovernmental laboratory companies. Seventy C. auris isolates were collected during the study period. These isolates predominantly originated from clinical ear discharge samples. Clade determination based on the internal transcribed spacer-D1/D2 regions and CauMT1 locus revealed that almost all isolates belonged to clade II; however, one ear discharge-derived isolate belonged to clade I, confirmed by whole genome sequencing. Regarding drug susceptibility, 20% of the isolates were resistant to fluconazole; however, none of the isolates exhibited polyene or echinocandin resistance. In summary, the C. auris isolates collected in Japan were generally derived from ear discharge samples and belonged to clade II. However, ear discharge-derived isolates may not belong exclusively to clade II. Although no invasive cases were reported during the study period, continuing surveillance programs to clearly describe the domestic epidemiology is necessary.