Evaluation of a Prototype of a Novel Galactomannan Sandwich Assay Using the VIDAS(®) Technology for the Diagnosis of Invasive Aspergillosis

OBJECTIVES: To evaluate the analytical and clinical performance of a prototype of a VIDAS(®) Galactomannan (GM) unitary test (bioMérieux, Marcy l’Etoile, France) and compare to that of the Platelia™ Aspergillus Ag assay (Bio-Rad, CA, USA). METHODS: Repeatability, reproducibility, and freeze-thaw stability of VIDAS(®)GM were evaluated. Sera from patients at risk of IA were concurrently tested with both the VIDAS(®)GM and Platelia™ Aspergillus Ag assays. Correlations between the two assays were assessed by Passing Bablok (PB) regression and performance by ROC analysis. RESULTS: The correlations between the VIDAS(®)GM indexes after one and two cycles of freezing/thawing were r=1.00 and r=0.989, respectively. The coefficients of variation for negative, low-positive, and positive sera were 13%, 6%, and 5% for repeatability and 14.4%, 7.2%, and 5.5% for reproducibility. Overall, 126 sera were tested with both assays (44 fresh and 82 frozen). The correlation between VIDAS(®)GM and Platelia™ Aspergillus Ag was r=0.798. The areas under the curve of the ROC analyses were 0.892 and 0.894, for VIDAS(®)GM and Platelia™ Aspergillus Ag, respectively. CONCLUSIONS: This new VIDAS(®)GM prototype assay showed adequate analytical and clinical performance and a good correlation with that of Platelia™ Aspergillus Ag with 126 sera, although these results need to be confirmed in a larger prospective and multicentric study. As for the other VIDAS(®) assays, VIDAS(®)GM is a single-sample automated test using a solid reagent strip and receptacle. It is easy to use and suitable for rapid on-demand test results.