Rapid Detection of Candida albicans by Polymerase Spiral Reaction Assay in Clinical Blood Samples.

Xiaoqun Jiang,Lihong Bian,Da Ao,Liuyu Huang,Simo Huang,Zhan Yang,Dayang Zou,Wei Liu,Derong Dong,Xiaoming He,Ningwei Liu

doi:10.3389/fmicb.2016.00916

Abstract

Candida albicans is the most common human yeast pathogen which causes mucosal infections and invasive fungal diseases. Early detection of this pathogen is needed to guide preventative and therapeutic treatment. The aim of this study was to establish a polymerase spiral reaction (PSR) assay that rapidly and accurately detects C. albicans and to assess the clinical applicability of PSR-based diagnostic testing. Internal transcribed spacer 2 (ITS2), a region between 5.8S and 28S fungal ribosomal DNA, was used as the target sequence. Four primers were designed for amplification of ITS2 with the PSR method, which was evaluated using real time turbidity monitoring and visual detection using a pH indicator. Fourteen non-C. albicans yeast strains were negative for detection, which indicated the specificity of PSR assay was 100%. A 10-fold serial dilution of C. albicans genomic DNA was subjected to PSR and conventional polimerase chain reaction (PCR) to compare their sensitivities. The detection limit of PSR was 6.9 pg/μl within 1 h, 10-fold higher than that of PCR (69.0 pg/μl). Blood samples (n = 122) were collected from intensive care unit and hematological patients with proven or suspected C. albicans infection at two hospitals in Beijing, China. Both PSR assay and the culture method were used to analyze the samples. Of the 122 clinical samples, 34 were identified as positive by PSR. The result was consistent with those obtained by the culture method. In conclusion, a novel and effective C. albicans detection assay was developed that has a great potential for clinical screening and point-of-care testing.

Highlights

Candida albicans is an important human yeast pathogen that accounts for the majority of superficial and systemic infections caused by the Candida genus (Fan et al, 2008; Sobel, 2015)
Fourteen non-C. albicans yeast strains were included as negative controls in order to evaluate the specificity of the polymerase spiral reaction (PSR) method
The results indicated that PSR assay is highly sensitive for the detection of C. albicans

Summary

Introduction

Candida albicans is an important human yeast pathogen that accounts for the majority of superficial and systemic infections caused by the Candida genus (Fan et al, 2008; Sobel, 2015). Candidemia, the most common form of systemic candidiasis, is the fourth most frequent cause of nosocomial bloodstream infections with a mortality rate of about 50% (Gudlaugsson et al, 2003; Kibbler et al, 2003). The morbidity of invasive candidiasis has been increasing in recent years due to the widespread use of broad-spectrum antibiotics, hormone drugs, and immunosuppressants, while invasive treatment such as endotracheal intubation and mechanically ventilation is an important risk factor (Kim and Sudbery, 2011; Tang et al, 2016). Because Candida spp. differ in their patterns of resistance to common antifungals, differentiation of C. albicans from other. Early and accurate identification of C. albicans is critical, especially in patients with suspected symptoms of invasive candidiasis

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Conclusion