A selective medium for isolation and detection of Candida auris; an emerging pathogen.

Objective: Identification of Candida auris is challenging and requires molecular or protein profiling-based approaches which are limited in many routine diagnostic laboratories necessitating the development of a cost-effective, rapid, and reliable method of identification. The objective of this study was to develop a selective medium for C. auris identification.Methods: Eighteen C. auris and thirty non- auris yeasts were used for the standardization of the selective medium. Sodium chloride (10% to 13%) along with ferrous sulphate (8 mM to 15 mM) were added to yeast peptone dextrose (YPD) agar in various combinations and incubating at 37°C, 40°C and 42°C for 2-3 days. For validation, 579 yeast isolates and 40 signal-positive BACTEC blood culture (BC) broths were used.Results: YPD agar comprising 12.5% NaCl and 9 mM ferrous sulphate incubated at 42°C for 48 hours allowed selective growth of C. auris Ninety-five percent (127/133) of C. auris isolates tested grew on the standardized media within 48 h and the rest six grew after 72 h, while the growth of 446 non-auris yeast isolates was completely inhibited. The specificity and sensitivity of the test medium were both 100% after 72 hours of incubation. The positive and negative predictive values were also noted 100% after 72 hours of incubation.Conclusion: The formulated selective medium can be used for the detection and identification of C. auris The medium is inexpensive, can easily be prepared and can be used as an alternative to molecular diagnostic tools in the clinical microbiology laboratory.