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Original article
Diagnostic accuracy of fungal PCR and β-d-glucan for detection of candidaemia: a preliminary evaluation
  1. Cara McKeating1,
  2. P Lewis White2,
  3. Raquel Posso2,
  4. Michael Palmer3,
  5. Elizabeth Johnson3,
  6. Ronan McMullan1,4
  1. 1 Department of Microbiology, Belfast Health and Social Care Trust, The Royal Hospitals, Belfast, UK
  2. 2 Mycology Regional Reference Unit, University Hospital of Wales, Cardiff, UK
  3. 3 Mycology Reference Laboratory, Public Health England South West, Bristol, UK
  4. 4 Centre for Experimental Medicine, Queen’s University Belfast, Belfast, UK
  1. Correspondence to Dr Cara McKeating, Department of Microbiology, Belfast HSC Trust, The Royal Hospitals, Belfast BT12 6BA, UK; caramckeating{at}gmail.com

Abstract

Aims Although treatment for candidaemia is time critical, culture-based tests prolong turnaround times and may promote underdiagnosis. Non-culture-based tests have the potential to overcome these difficulties but are in limited clinical use. The aim of this work was to undertake an initial evaluation of two non-culture-based tests for diagnosis of candidaemia.

Methods Patients with candidaemia were identified prospectively over a 4-month period. Sera drawn from case (candidaemic) and control (non-candidaemic) patients on the same day as the positive blood culture were tested with both the Renishaw RenDx Fungiplex test and a commercial β-d-glucan (BDG) assay (Fungitell, Associates of Cape Cod). Sensitivity and specificity were calculated independently and in combination, using paired blood culture as the reference standard.

Results There were 10 eligible case patients and 39 negative controls. PCR sensitivity and specificity were found to be 44.4% (95% CI 18.9% to 73.3%) and 87.2% (72.8% to 94.8%), respectively. BDG sensitivity and specificity were 80% (47.9% to 95.4%) and 89.7% (75.9% to 96.5%), respectively. When combining PCR and BDG, sensitivity was 90% (95% CI 57.4% to 100%) and specificity was 79.5% (64.2% to 89.5%). When two sequential specimens were tested, PCR sensitivity increased to 60% (95% CI 31.2% to 83.3%) and BDG sensitivity to 90% (54.7% to 100%).

Conclusion A combination of tests, or a single test at multiple time points, may be preferable to relying on one test at a single time point. This should be accounted for in design of future diagnostic accuracy studies of tests for invasive candidosis.

  • yeast
  • mycology
  • infections
  • fungi
  • diagnostics

https://doi.org/10.1136/jclinpath-2017-204692

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    Footnotes

    • Handling editor Tony Mazzulli.

    • Contributors The study was designed and overseen by RMM. CMK drafted the manuscript. PLW, RP, MP and EJ carried out the index tests and edited the manuscript.

    • Competing interests CM has received sponsorship from Astellas to attend an educational meeting. PLW is a founding member of the EAPCRI; has received project funding from Myconostica, Luminex, Renishaw diagnostics and Bruker; has received sponsorship from Myconostica, MSD, Launch, Bruker and Gilead Sciences to attend international meetings; has provided consultancy for Renishaw Diagnostics Limited; and is a member of the advisory board and speaker bureau for Gilead Sciences. RM has received sponsorship from Astellas and Gilead Sciences to attend international meetings; has been awarded research funding from the UK National Institute for Health Research to study rapid tests for fungal infection, from Innovate UK to develop a point of care test to detect sepsis pathogens, and from Pfizer to study non-culture tests for Aspergillus infection. All other authors have no competing interests to declare.

    • Provenance and peer review Not commissioned; externally peer reviewed.