Document Type : Original Articles
Department of Medical Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Prof. Alborzi Clinical Microbiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
Background and Purpose: Candida auris is an emerging multidrug-resistant pathogen. The identification of this species with the conventional phenotypic or biochemical mycological methods may lead to misidentification. Molecular-based species-specific identification methods such as quantitative real-time polymerase chain reaction (qPCR) facilitate a more reliable identification of C. auris than mycological methods. Regarding this, the present study aimed to develop a hydrolysis probe-based qPCR assay for the rapid, accurate identification of C. auris.
Materials and Methods: The internal transcribed spacer 2 regions in the nuclear ribosomal DNA of C. auris and other related yeasts were assayed to find a specific PCR target for C. auris. A 123-base-pair target was selected, and primers and a probe were designed for hydrolysis probe-based real-time PCR with TaqMan chemistry. Ten-fold serial dilutions of C. auris ranging from 106 to 100 CFU/mL were prepared to establish a standard curve to quantify the yeast.
Results: The qPCR assay was able to identify and quantify C. auris with a detection limit of 1 C. auris CFU per reaction. Specificity was confirmed by the non-amplification of the sequences belonging to other Candida species, yeasts, molds, bacteria, or human DNAs. The standard curve of the assay showed a highly significant linearity between threshold values and dilution rates (R2=0.99; slope=−3.42).
Conclusion: The applied qPCR assay facilitated the rapid and accurate identification and quantification of emerging opportunistic C. auris. Therefore, considering the promising test validation results, we succeeded to develop a rapid and accurate hydrolysis probe-based qPCR assay for the screening and identification of C. auris.