Access Toxo IgG

The Access Toxo IgG assay is a chemiluminescent immunoassay that detects IgG antibodies to Toxoplasma gondii in human serum to diagnose toxoplasmosis infection and assess immune status in pregnant women. The assay runs on the DxI 9000 Access Immunoassay Analyzer and provides qualitative and quantitative results, though it is not cleared for blood donor screening and performance has not been established in immunocompromised patients, cord blood, or infants.

The candidate device uses the same two-step chemiluminescent immunoenzymatic technology, analyte target (IgG antibody to T. gondii), capture reagent (paramagnetic particles with T. gondii membrane antigen), and detection antibody as the predicate. The primary differences are the substrate (Lumi-Phos PRO instead of Access Substrate) and the instrument platform (DxI 9000 instead of Access 2), though both achieve the same measuring interval of qualitative/quantitative detection with identical result interpretation thresholds.

CLSI EP05-A3 (precision performance), CLSI EP06-2nd Edition (linearity evaluation), CLSI EP17-A2 (detection capability), and CLSI EP12-Ed3 (qualitative binary output performance).

The candidate device demonstrates substantial equivalence because it maintains identical intended use, analyte, assay technology, calibration frequency, sample type, and result interpretation as the predicate. Method comparison testing shows 100% positive and negative percent agreement between the two instruments across 140 serum samples. Precision, linearity, and detection limit studies on the DxI 9000 meet the same performance specifications as the predicate, establishing that the substrate and instrument differences do not adversely affect clinical performance.