Validation and Implementation of Real Time PCR for Rapid Identification of Candida auris from Clinical Surveillance Samples in a Local Public Health Laboratory Setting

Background Candida auris is a worldwide emerging pathogen known for causing infections and outbreaks in health care settings. In Orange County, CA, C. auris has been circulating and causing outbreaks in long term care facilities since 2019, with a total of 1,017 cases detected from February 2019 to December 2021. Objective To evaluate an rt-PCR assay for rapid identification and assessment of colonization of C. auris from patient surveillance samples at the OC Public Health Laboratory. Method An extraction protocol using the MasterPure kit and automated EZ1 Advanced XL followed by rt-PCR using PerfeCTa Multiplex qPCR TaqMan, and the 7500 Fast Dx was conducted. The assay was evaluated using 131 previously confirmed patient samples and 123 prospective fresh samples from different body sites. Results The assay was highly reproducible at an LOD of 230 CFU/ml. The sensitivity and specificity of the 131 samples was 90 % and 86 % respectively and for the 123 samples it was 93% and 90% respectively. ROC analysis was calculated using all samples (n = 254) to determine the most ideal diagnostic value. The AUC was 0.922 and optimal cutoff was a cycle threshold 36.78. A CT ≤37.00 is the ideal diagnostic value for patient surveillance samples. Conclusion The successful implementation of the rt-PCR assay for C. auris in a local public health laboratory allows for accurate and rapid screening and identification of C. auris which can contribute to enhanced surveillance and control of C. auris spread in local health care facilities.