Identification of Candida auris using the updated 8.01 VITEK®2 yeast identification system: a multi-laboratory evaluation study

Introduction Candida auris is an emerging multidrug-resistant yeast that has been systematically incorrectly identified by phenotypic methods in clinical microbiology laboratories. VITEK®2 automated identification system (bioMerieux) recently included C. auris in its database (version 8.01). Material and methods We evaluated the performance of VITEK®2 (YST ID Card) to identify C. auris and related species. A panel of 44 isolates of Candida species (C. auris, n=35; C. haemulonii, n=5; C. duobushaemulonii, n=4) were tested by three different hospital-based microbiology laboratories. Results Among 35 isolates of C. auris, VITEK®2 yielded correct identification in an average of 52% of tested samples. Low discrimination results were obtained in an average of 27% with inability to distinguish between C. auris, C.duobushaemulonii and C. famata. Incorrect identification results were obtained in an average of 21%, the majority (91%) of which were reported as C. duobushaemulonii and 9% as C. lusitaniae/C. duobushaemulonii. Proportion of correct identification was not statistically different across different centers (p=0,78). Stratification by genetic clades demonstrated that 100% (n=8) of the strains of the South American clade were correctly identified, compared to 7% (n=10) and 0% (n=4) from the African and East Asian clade respectively. None of the non-auris Candida strains (n=9) were incorrectly identified as C. auris. Conclusion Our results show that VITEK®2 (version 8.01) yeast identification system has a limited ability to correctly identify C. auris. This data suggests that an identification result for C. duobushaemulonii should warrant further testing to rule out C. auris. Overall performance of VITEK®2 seems to differ according to C. auris genetic clade with the South American isolates yielding the most accurate result.