Evaluation of Aspergillus Galactomannan Lateral Flow Assay on Serum and Bronchoalveolar Lavage Specimens

Background: Detection of biomarkers, such as galactomannan (GM), has proven to be of great significance in early recognition of invasive aspergillosis (IA). The aim of our study was to evaluate the lateral flow assay (LFA) for the detection of GM on serum and bronchoalveolar lavage (BAL) samples previously proven positive by enzyme-linked immunosorbent assay (ELISA). Methods: The study was performed on serum and BAL samples obtained from patients with suspected IA in the period from February 2019 to January 2020, which were previously GM positive by ELISA (Platelia Aspergillus Ag, Biorad, Hercules, USA). Samples were then tested by LFA (Aspergillus Galactomannan LFA, IMMY, Oklahoma, USA) with test line intensity visually read as 1+, 2+, 3+, or 4+. Results: A total of 45 GM ELISA positive serum and/or BAL samples were obtained from 41 patients; 25 (55,6 %) were BAL and 20 (44,4 %) serum samples. LFA showed a positive result in 39 out of 45 (86,7%) GM ELISA positive samples; 22/25 (88.0 %) BAL samples and 17/20 (85.0 %) serum samples tested positive. In BAL samples, low intensity test line of 1+ was significantly more frequent in GM ELISA positive samples with optical density index (ODI) < 1.0 (p=0.0002). Three serum samples with high GM ELISA ODI (>4.0) had low intensity line of 1+ when tested with LFA. Conclusions: Results obtained by LFA are comparable to GM ELISA. Since low intensity lines were found in serum samples with high ODI, this potentially makes BAL a superior sample for LFA, at least when visual and not automated reading is done.