Assessment of the diagnostic performance of the IDS-iSYS tests for toxo IgG, toxo IgM and avidity

• IDS-iSYS test, based on chemiluminescence was evaluated for diagnosing toxoplasmosis.
• The IDS-iSYS was tested in parallel with Architect and an inhouse avidity test.
• Seven hundred eighty three unselected samples were prospectively included.
• Sensitivity and specificity were 99% and 99% for IgG, and 75% and 97% for IgM.
• IDS-iSYS appears to be a reliable and easy-to-use tool for diagnosing toxoplasmosis.

When acquired during pregnancy toxoplasmosis can have devastating consequences on the fetus. As maternal infection is in the majority of cases subclinical, the diagnosis of toxoplasmosis relies on serological tests for the detection of IgG, IGM and the mesure of IgG avidity. We evaluated the performance of IDS-iSYS a new automatized instrument based on chemiluminescence for the diagnosis of the disease. Our study was based on non-selected samples received in our laboratory either for the determination of serological status or for distinguishing acute from chronic infection. Seven hundred eighty three samples were enrolled in the study. Compared with Architect IgG and IgM assays, the sensitivity and specificity were respectively 99% and 99% for IgG, and 75% and 97% for IgM. We observed higher remaining titers for IDS iSYS IgG, which could reduce the proportions of patients who have to be retested because of doubtful titers. IgM detection and avidity scored equivalent performance with both methods. This automate appears to be a reliable and easy-to-use tool for diagnosing toxoplasmosis in different clinical settings.