[en] Objectives
Microbiological diagnosis of invasive candidiasis is still dependent on culture-based methods. The use of beta-D-glucan antigen detection is included in the EORTC microbiological diagnostic criteria but is rarely available in the clinical labs. On the other hand, PCR-based methods lack standardization. The RenDx Fungiplex® is a new commercially available semi-automated PCR SERS assay designed for the detection of Aspergillus sp. and Candida sp. including the differentiation of resistant strains as C. glabrata, C. krusei and A. terreus. This study was performed for sensitivity and reproducibility testing of the method on 8 different Candida species.
Methods
The study was conducted on EDTA-blood collected from a healthy donor. Blood samples were spiked with 10 Candida reference strains: C. albicans ATCC 10231, C. albicans NEQAS 1206 and C. albicans NEQAS 2359; C. glabrata ATCC 90030 ; C. krusei ATCC 6258 ; C. tropicalis NEQAS 1036 ; C. guillermondii NEQAS 1035 ; C. parapsilosis ATCC 22019 ; C. lusitaniae NEQAS 1511 and C. dubliniensis IHEM 14280. Spiked samples were diluted at final concentrations ranging from 1 CFU/mL to 1000 CFU/mL. Cultures on Sabouraud dextrose agar were performed in parallel to control yeasts dilutions. DNA extraction was performed by using proteinase K-based method followed by purification on QIAcube automate. The RenDx Fungiplex®kit (Renishaw) was used for the amplification process and the final detection was processed on the SP-1000 sample analyzer. Reproducibility testing was performed on the three C. albicans reference strains by repeating each test 5 times.
Results
A total of 142 samples were included in the study. A sensitivity of 10 CFU/mL was reached for C. glabrata, C. krusei, C. tropicalis, C. dubliniensis spiked samples while C. lusitaniae and C. tropicalis performed better at 1 CFU/mL. The three tested reference C. albicans strains and C. guillermondii gave the lowest sensitivity (100 CFU/mL). The reproducibility of the assay was 96%
Conclusion
RenDx Fungiplex®kit allows the detection of the most frequent Candida species responsible for invasive candidiasis in spiked blood samples. The sensitivity of the test is comprised between 10 and 100 CFU/mL for most Candida sp. and reproducibility is very high. This evaluation allows us to consider this commercial kit for inclusion in a clinical study on invasive candidiasis in comparison with non-molecular diagnostic assays.
Disciplines :
Laboratory medicine & medical technology
Author, co-author :
HAYETTE, Marie-Pierre ; Centre Hospitalier Universitaire de Liège - CHU > Microbiologie clinique
WERY, Marie ; Centre Hospitalier Universitaire de Liège - CHU > Microbiologie clinique
BOREUX, Raphaël ; Centre Hospitalier Universitaire de Liège - CHU > Microbiologie clinique
PEETERS, Sylvian ; Centre Hospitalier Universitaire de Liège - CHU > Génétique
STIRLING, Emma; Renishaw Diagnostics Limited, Glasgow, UK
STEVENSON, Ross; Renishaw Diagnostics Limited, Glasgow, UK
LAYIOS, Nathalie ; Centre Hospitalier Universitaire de Liège - CHU > Soins intensifs
Language :
English
Title :
Evaluation of a commercially developed semi-automated PCR-surface enhanced raman scattering assay for the detection of Candida species in blood
Alternative titles :
[en] Evaluation d'un test commercial semi-automatique PCR-SERRS pour la détection de Candida sp. dans le sang