A rapid and automated sample-to-result Candida auris real-time PCR assay for high throughput testing of surveillance samples with BD MAXâ„¢ open system

The multidrug-resistant yeast pathogen Candida auris continues to cause outbreaks and clusters of clinical cases worldwide. Previously, we developed a real-time PCR test for the detection of C. auris from surveillance samples (Leach et al. JCM. 2018: 56, e01223-17); the test played a crucial role in the ongoing investigations of C. auris outbreak in New York City. To ease the implementation of the test in other laboratories, we developed an automated sample-to-result real-time C. auris PCR using BD MAX™ open system, a platform proven to be adaptable for direct detection of other fungal pathogens. We optimized sample extraction at three different temperatures and four incubation periods, sensitivity was determined using eight pools of patient samples, and specificity was calculated using four clades of C. auris , and closely and distantly related yeasts. Three independent extractions and testing of two patient sample pools in the quadruplicate yielded assay precision. BD MAX™ optimum assay conditions were: DNA extraction at 75°C, 20 min, and the use of PerfeCTa Multiplex qPCR Toughmix. The limit of detection (LOD) of the assay was one C. auris CFU/PCR reaction; we detected all four clades of C. auris without cross-reactivity to other yeasts. Of the 110 patient surveillance samples tested, 49 were positive for C. auris using the BD MAX™ System with 94% clinical sensitivity and 94% accuracy compared to the manual assay. BD MAX™ assay allows high throughput screening of 180 C. auris surveillance samples in a 12-hour workday.