MULTICENTER EVALUATION OF A NEW COMMERCIAL ASSAY FOR DETECTION OF IMMUNOGLOBULIN-M ANTIBODIES TO TOXOPLASMA-GONDII

A new commercial assay for detection of IgM-specific antibodies to Tox oplasma gondii (IMx Toro IgM, Abbott, USA), based on microparticle enz yme immunoassay technology, was evaluated at 15 clinical sites in Euro pe and the USA. Performance characteristics were established by testin g clinical specimens collected randomly from pregnant women, blood don ors, individuals with suspected Toxoplasma gondii infection and indivi duals confirmed HIV positive. Reference testing was performed using To xo-M EIA (Abbott). Specimens evaluated at European sites yielding disc ordant results between the new assay and the reference EIA were furthe r tested with an immunosorbent agglutination assay; at sites in the US A, discordant results were resolved using Platelia Toro IgM (Sanofi, F rance) and Vidas Toro IgM (bioMerieux, France) assays. In addition, ma tched plasma and serum, heat-treated and non-heat-treated specimens, a nd fresh and frozen specimens were evaluated at the USA sites. At Euro pean sites the new commercial assay had a sensitivity of 95.6% (196/20 5), a specificity of 99.8% (3,137/3,143) and an agreement of 99.6% (3, 333/3,348) following resolution of discordant results; sensitivity in the USA was 97.4% (184/189), specificity was 99.8% (1,204/1,207) and a greement was 99.4% (1,388/1,396) following resolution. The new IMx Tor o IgM is a sensitive and specific assay for measurement of IgM antibod ies to Toxoplasma gondii in human serum and plasma.