Evaluation of the FIAX semiautomatic fluorescent immunoassay system for the detection of IgG antibodies to Toxoplasma gondii

Abstract

A commercially available solid phase fluoroimmunoassay system (FIAX, International Diagnostic Technology, Santa Clara, CA) was evaluated in parallel with a standard indirect fluorescent-antibody test (IFAT) for the detection of IgG antibodies to Toxoplasma gondii. Titers obtained by the FIAX method on the 101 patient samples correlated well with the standard procedure. Sensitivity of the FIAX system was 96% and specificity was 93%. A method for measuring serum titer reproducibility applicable to both conventional doubling dilution and to automated procedures was employed, allowing a meaningful comparison of precision in the two systems. It was found that titer reproducibility in the FIAX system was better than that of the IFAT and exceeded that expected with most conventional double-dilution serological procedures. The FIAX system will most benefit those laboratories with relatively large numbers of samples which can be batch tested.