Automated Detection of Candida auris Direct from Whole Blood by T2MR

BACKGROUND: Candida auris is now recognized worldwide as a virulent pathogen that is difficult to manage, resulting in high mortality rates. The majority of C.auris isolates have exhibited resistance to one or more antifungal agents. Nosocomial infections caused by C.auris are growing due to the increasing rate of colonization and environmental causes. The diagnostic tests available for the identification of C. auris are limited to date. Additionally, microbiological cultures and subsequent identification of Candida species require 2–5 days, and have a sensitivity of approximately 50%. Accurate diagnosis of a C. auris infection is also hampered by misidentification of C. auris as other species, commonly C. haemulonii and Saccharomyces cerevisiae. Here we evaluate the use of the T2MR platform for the highly sensitive, rapid species level identification of C. auris, C. lusitaniae and C. haemulonii in whole blood samples. METHODS: A multiplex assay targeting C. auris, C. lusitaniae, and C. haemulonii was developed using cultured cells spiked in K(2)EDTA anticoagulated blood from healthy human donors. C. auris isolates received from the CDC were cultured overnight, automated cell counting was used to determine concentration. From this stock, the culture was diluted to a target titer, and inoculated into whole blood, followed by confirmation plating to confirm cell titer. Four mL spiked blood samples were processed on the T2Dx Instrument. RESULTS: Sensitive and specific detection of C. auris was achieved direct from blood in less than 4 hours on the T2Dx Instrument. A Limit of Detection (LoD) for C. auris was demonstrated to be ≤10 CFU/mL. T2MR signals of samples spiked with target were approximately 30 times higher than samples with no target present, and no cross reactivity was observed between C.auris, C. haemulonii, C. lusitaniae and C. krusei. CONCLUSION: Low concentrations of Candida cells can be detected and identified by T2MR. This prototype assay potentially allows for the rapid screening and identification of patients infected with Candida auris with high specificity and sensitivity, aiding in the hospital management and targeted therapy of this emerging multi-drug resistant pathogen. DISCLOSURES: B. Manning, T2 Biosystems: Employee and Shareholder, Salary; J. L. Snyder, T2 Biosystems: Employee and Shareholder, Salary; B. Chang, T2 Biosystems: Employee and Shareholder, Salary; C. Wong, T2 Biosystems: Employee and Shareholder, Salary; T. Higa, T2 Biosystems: Employee and Shareholder, Salary; R. Shivers, T2 Biosystems: Employee and Shareholder, Salary; T. J. Lowery, T2 Biosystems: Employee and Shareholder, Salary