Candida auris is a pathogenic yeast that causes invasive infections with high mortality. Infections most often occur in intensive care units of health care facilities. It is crucial to trace the source and prevent further spread of C. auris during an outbreak setting; therefore, genotyping of C. auris is required. To enable fast and cost-effective genotyping, we developed a short tandem repeat (STR) typing assay for C. auris. STRs in C. auris were identified, and from an initial selection of 23 STRs, 12 were used to develop a STR typing assay. Having shown that the STR typing assay was reproducible and specific, a robust set of 444 C. auris isolates was investigated to identify genotypic diversity. In concordance with whole-genome sequencing (WGS) analysis, we identified five major different C. auris clusters of South American, South Asian, African, East Asian, and Iranian origin. Overall, a total of 40 distinct genotypes were identified, with the largest variety in the South Asian clade. Comparison with WGS demonstrated that isolates with <20 single nucleotide polymorphisms (SNPs) are mostly not differentiated by STR analysis, while isolates with 30 or more SNPs usually have differences in one or more STR markers. Altogether, a highly reproducible and specific STR typing assay for C. auris was developed; this assay distinguishes the five different C. auris clades in identical fashion to WGS, while most isolates differing by >30 SNPs, as determined via WGS, are also separated. This new C. auris-specific genotyping technique is a rapid, reliable, and cost-effective alternative to WGS analysis to investigate outbreaks.

IMPORTANCE Candida auris is an emerging fungal pathogen now recognized as a threat to public health. The pathogen has spread worldwide and causes mainly hospital-associated outbreaks. To track and trace outbreaks and to relate them to new introductions from elsewhere, whole-genome sequencing and amplified fragment length polymorphism (AFLP) have been used for molecular typing. Whole-genome sequencing is costly and available only at a few centers, and AFLP is a complicated technique and hard to interpret. We describe a novel simple STR genotyping technique based on short tandem repeats in the C. auris genome. We also show that the performance of this STR-based genotyping technique has proven comparable to that of WGS. Overall, this work provides a novel, rapid, reliable, and cost-effective method of molecular outbreak investigations of C. auris.

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Citation:  de Groot T, Puts Y, Berrio I, Chowdhary A, Meis JF. 2020. Development of Candida auris short tandem repeat typing and its application to a global collection of isolates.
mBio 11:e02971-19. https://doi.org/10.1128/mBio.02971-19.

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