A New and Highly Sensitive Serum Mannoprotein Lateral Flow Assay for Point-of-Care Diagnosis of Invasive Aspergillosis (Tripathy Method).

Abstract

Background and objectivesThe mannoprotein lateral flow assay (MP-LFA) or Aspergillus-specific lateral flow device (AspLFD) is a novel rapid test for point-of-care diagnosis (PoC) of invasive aspergillosis (IA), but its routine clinical application is hampered due to low sensitivity (Sn) of the assay in serum. Therefore, this study aimed to develop a new method to enhance the Sn of the serum MP-LFA.MethodologyIn the new method (Tripathy method), we used direct heating of the serum without any dilution at 120°C for 15 minutes to purify the mannoprotein (MP) antigen of the Aspergillus. The MP-enriched serum supernatant obtained after centrifugation was loaded in an LFD cassette, and the results were read after 20 minutes using a digital cube reader. In parallel to our new method, AspLFD was performed according to the manufacturer’s instructions. The diagnostic performance of the two methods was evaluated using paired sera of true IA patients (IA, n=18) and healthy subjects (controls, n=20). The positivity of the two methods was also evaluated in the sera of leukemia patients with possible/probable IA (possible/probable IA; n=23).ResultsThe Tripathy method had a significantly higher sensitivity (88.9% versus 55.5%; p<0.05) and diagnostic odds ratio (72.0 versus 23.7) than the standard AspLFD method. In receiver operating characteristic curve analysis for differentiation between IA patients and controls, although the Tripathy method (area under curve; AUC: 0.894, p<0.001) and AspLFD method (AUC: 0.753, p<0.001) were significantly associated with IA, the AUC of the Tripathy method was significantly higher than that of the AspLFD method (0.894 versus 0.753; p<0.05). In the sera of possible/probable IA, MP-LFA by the Tripathy method had a significantly higher rate of positivity than the AspLFD method (39.0% versus 21.7%; p<0.05).ConclusionOur data show that the Tripathy method is a highly sensitive method of MP-LFA for the PoC diagnosis of IA in clinical settings.