Evaluation of a Multiplex Bead Assay for Strongyloides stercoralis diagnosis using the recombinant antigen rSs-NIE-1

Abstract

Strongyloides stercoralis diagnosis is still a challenge to public health. Multiplex assays offer the advantage of testing several parameters simultaneously, which could allow the detection of several parasitic infections at the same time. This study aimed to evaluate the sensitivity and specificity of a Multiplex Bead Assay (MBA) in MagPix® platform for S. stercoralis diagnosis using a recombinant antigen to detect different isotypes of specific antibodies. This study enrolled 330 alcoholic male inpatients. Parasitological examination was performed on three fecal samples. Sera samples were tested with MBA for IgG, IgG1, IgG4, IgA1 and IgE antibodies against S. stercoralis recombinant antigen rSs-NIE-1, and for IgG antibody against recombinant antigens of Toxocara canis excretory–secretory antigen (Tc-CTL-1) and microsomal fraction of Schistosoma mansoni adult worms (MAMA). The MBA did not present reactions for IgA1 or IgE detection. The highest sensitivity was observed in NIE-IgG (95.7 %), while the highest specificity was demonstrated in NIE-IgG1(92.3 %). However, based on the likelihood ratio (LR), the best diagnostic test was NIE-IgG4 (LR 9.96). Possible cross-reactions were observed in all antibody isotypes tested, mainly for NIE-IgG. This study demonstrates that MBA can be used as an alternative diagnostic tool for S. stercoralis infection, particularly in the detection of IgG4-specific antibodies.