Validation and implementation of a commercial real‐time PCR assay for direct detection of Candida auris from surveillance samples

Abstract

Background Rapid and reliable laboratory methods are required for detecting the nosocomial yeast Candida auris. AurisID® (Olm Diagnostics) is a real‐time PCR assay approved for detecting C. auris in fungal cultures and directly from blood samples, involving a nucleic acid extraction as a prior step. Objectives The purpose of this study is to validate the AurisID® kit for direct detection of C. auris from surveillance samples without prior DNA extraction and to analyse the results of implementing this methodology to our daily laboratory routine protocol for C. auris surveillance studies. Methods Our PCR method using the AurisID® kit was compared with our routine protocol, consisting of culture in CHROMagar® Candida and identification by mass spectrometry. A total of 113 swabs were used for validation and 136 pair of surveillance samples were tested. Limit of detection (LOD) was determined by using swabs in Amies transport medium, which were spiked in a series of dilutions of a C. auris standardised suspension (0.5 McFarland). Results The PCR method showed high sensitivity, specificity, predictive positive value and predictive negative value (96.6%, 100%, 100% and 98.2%, respectively) when compared with the routine protocol. LOD was 500 CFU/ml, which corresponds to approximately 1 CFU/PCR. Conclusions Our PCR method using the AurisID® kit allows a reduction in the turnaround time for surveillance of C. auris compared with other methods. These results are expected to contribute to control C. auris outbreaks, allowing isolation of patients and cleaning of environmental surfaces in advance.

Novel Chromogenic Medium CHROMagarTM Candida Plus for Detection of Candida auris and Other Candida Species from Surveillance and Environmental Samples: A Multicenter Study

“…Early diagnosis is key for the successful treatment of fungal infections, and more rapid and reliable tests are needed [ 34 , 35 ]. Non-culture-based methods, such as PCR, are rapid methods to diagnose yeast infections, although their use in clinical laboratories is still low, especially in resource-limited settings [ 36 ].…”

Fungal infections diagnosis – Past, present and future

“…including: Aspergillus fumigatus TR34/L98H mutations Serum BAL Biopsy NA 71 – 100%/84.6 – 100% [ 195 , 200 , 201 ] Asp ID (OlmDiagnostics) Multiplex real-time PCR Unknown Aspergillus spp. including: Aspergillus terreus - BAL 90 minutes (excluding DNA extraction) 94.1%/76.5% [ [200] , [201] , [202] ] Cand ID® and Auris ID® (OlmDiagnostics) Multiplex real-time PCR Unknown Cand ID: Candida albicans Candida dubliniensis Candida glabrata Candida krusei Candida parapsilosis Candida tropicalis Auris ID: Candida auris - Cand ID: Plasma Synthetic BAL Auris ID: Blood 45 min (excluding DNA extraction) CandID: NA Auris ID: 96.6%/100% [ 185 , 203 ] FungiPlex® Candida (Bruker Daltonics) Multiplex real-time PCR Unknown Candida albicans Candida parapsilosis Candida dubliniensis Candida tropicalis Candida glabrata Candida krusei - WB Serum Plasma <2 h (excluding DNA extraction) 98.4 – 100%/94.1 – 99.8% [ 183 , 185 ] PneumoGenius (PathoNostics) Real-time PCR Mitochondrial ribosomal large subunit (rLSU) and t...…”

So Many Diagnostic Tests, So Little Time: Review and Preview of Candida auris Testing in Clinical and Public Health Laboratories

“…AurisID R is a commercial kit with ready-made reagents for qPCR to identify C. auris from fungal culture (OLM Diagnostics, Newcastle upon Tyne, England) (Table 1). A retrospective evaluation with C. auris positive swab samples reported 96.6% sensitivity (Mulet Bayona et al, 2021). In a second study, AurisID R detected C. auris with an LOD of 1 genome copy/reaction but gave false positives with high DNA amounts of the C. haemulonii, C. duobushaemulonii, and C. pseudohaemulonii (Sattler et al, 2021).…”