Clinical use of fungal PCR from deep tissue samples in the diagnosis of invasive fungal diseases: a retrospective observational study

Abstract

Objectives: To assess the clinical use of panfungal PCR for diagnosis of invasive fungal diseases (IFDs). We focused on the deep tissue samples.

Methods: We first described the design of panfungal PCR, which is in clinical use at Helsinki University Hospital. Next we retrospectively evaluated the results of 307 fungal PCR tests performed from 2013 to 2015. Samples were taken from normally sterile tissues and fluids. The patient population was nonselected. We classified the likelihood of IFD according to the criteria of the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG), comparing the fungal PCR results to the likelihood of IFD along with culture and microscopy results.

Results: There were 48 positive (16%) and 259 negative (84%) PCR results. The sensitivity and specificity of PCR for diagnosing IFDs were 60.5% and 91.7%, respectively, while the negative predictive value and positive predictive value were 93.4% and 54.2%, respectively. The concordance between the PCR and the culture results was 86% and 87% between PCR and microscopy, respectively. Of the 48 patients with positive PCR results, 23 had a proven or probable IFD.

Conclusions: Fungal PCR can be useful for diagnosing IFDs in deep tissue samples. It is beneficial to combine fungal PCR with culture and microscopy.

Keywords: Deep tissue samples; diagnosis; fungal PCR; invasive fungal disease.