The utility of bronchoalveolar lavage beta-D-glucan testing for the diagnosis of invasive fungal infections

• We review bronchoalveolar-lavage (BAL) beta-D-glucan (BDG) testing in 132 patients.
• We compare the performance of BDG with galactomannan (GM) in BAL.
• BAL BDG is highly sensitive for Pneumocystis pneumonia.
• BAL BDG has similar sensitivity but inferior specificity to GM for aspergillosis.
• BDG results are poorly reproducible upon retesting in BAL but not in serum.

SummaryObjectivesTo investigate the utility of beta-D-glucan (BDG) testing in bronchoalveolar lavage (BAL) fluid for the diagnosis of invasive fungal infection (IFI), as compared to BAL galactomannan (GM).MethodsWe retrospectively reviewed medical records of 132 consecutive patients at the National Institutes of Health (NIH) in whom BAL BDG testing was performed for diagnosis of pneumonia. Using the European Organization for Research and Treatment of Cancer/Mycoses Study Group guidelines, we determined which patients had proven or probable IFI, and assessed the diagnostic performance of BAL BDG testing, relative to BAL GM. We also determined the reproducibility of the BDG assay in BAL via repeat testing of patient samples.ResultsTen patients had Pneumocystis pneumonia, and 34 patients had proven/probable IFI, including 14 with invasive aspergillosis (IA). BAL BDG was 100% sensitive for Pneumocystis. Although BAL BDG had similar sensitivity to BAL GM for the diagnosis of IA and IFI, it exhibited inferior specificity. Repeat testing demonstrated poor reproducibility of the BDG assay in BAL but not in serum.ConclusionsBDG testing exhibits poor specificity and reproducibility in BAL. Identification of the BAL-specific factors that may interfere with the performance of the assay could improve the clinical usefulness of BAL BDG testing.