(179 days)
The Elecsys Toxo IgG immunoassay is for the in vitro quantitative determination of IgG antibodies to Toxoplasma gondi in human serum and Li-heparin, K3-EDTA, and sodium citrate plasma. This assay is intended for use as an aid in the assessment of immune status and as an aid in the diagnosis of primary infection. The electrochemiluminescence immunoassay "ECLIA" is intended for use on the Elecsys and cobas e immunoassay analyzers. NOTE: This assay has not been cleared by the FDA for blood/plasma donor screening. Elecsys PreciControl Toxo IgG is used for quality control of the Elecsys Toxo IgG immunoassay on the Elecsys and cobas e immunoassay analyzers.
(1) The Elecsys Toxo IgG Immunoassay is a two-step sandwich immunoassay with streptavidin microparticles and electrochemiluminescence detection. In the first incubation, 10 µL of sample, a biotinylated recombinant T. gondii- specific antigen, and a T. gondii-specific recombinant antigen labeled with a ruthenium complex a form a sandwich complex. Then, after addition of streptavidin-coated microparticles, the complex becomes bound to the solid phase via interaction of biotin and streptavidin. The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier. Results are determined via a calibration curve which is instrument-specifically generated by 2-point calibration and a master curve provided via the reagent barcode. A human serum-based calibrator is provided with the test kit, and the recommended control material is PreciControl Toxo IgG. (2) The Elecsys Precicontrol Toxo IgG contains two levels of human serum with Toxo IgG antibodies.
The document describes the Elecsys Toxo IgG Test System, an immunoassay for the quantitative determination of IgG antibodies to Toxoplasma gondii.
Here's an analysis of the acceptance criteria and the study proving the device meets them:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria for each reported performance characteristic are not explicitly stated in a single "acceptance criteria" section. However, based on the reported data, we can infer the criteria used:
| Performance Characteristic | Acceptance Criteria (Inferred) | Reported Device Performance |
|---|---|---|
| Method Comparison (vs. Reference Method) | ||
| US Routine Clinical Specimens | ||
| Negative Agreement | High negative agreement | 93.4% (310/332) (90.1%-95.8% CI) |
| Positive Agreement | High positive agreement | 100% (183/183) (98.0%-100.0% CI) |
| European Site Prospective Study | ||
| Negative Agreement | High negative agreement | 91.1% (288/316) (87.5-94.0% CI) |
| Positive Agreement | High positive agreement | 99.3% (151/152) (96.4-100.0% CI) |
| European Site Frozen Samples | ||
| Negative Agreement | High negative agreement | 68.1% (32/47) (52.9-80.9% CI) |
| Positive Agreement | High positive agreement | 99.7% (378/379) (98.5-100.0% CI) |
| Precision | Consistent and low variability | |
| Intrassay (Low Control) | Low SD | SD = 0.02-0.05 IU/mL |
| Intrassay (High Control) | Low CV% | 2.02-4.78 CV % |
| Intrassay (Plasma 1 IU/mL) | Low CV% | CV 1.76-3.09% |
| Inter-assay (Low Control) | Low SD | SD 0.047 -0.077 IU/mL |
| Inter-assay (High Control) | Low CV% | CV 2.9-5.1 % |
| Inter-assay (Plasma 5 IU/mL) | Low CV% | CV 2.7-5.3% |
| Limit of Blank (LoB) | Clearly defined upper limit | 0.130 IU/mL |
| Limit of Detection (LoD) | Clearly defined lower limit | 0.175 IU/mL |
| Analytical Specificity (Cross-reactivity) | No significant cross-reactivity with common interfering substances (e.g., RF, ANA, EBV). Minimal impact from other infections. | No cross-reactivity or interference due to RF, ANA, and EBV. 4 out of 186 non-Toxo samples showed positive by Elecsys Toxo IgG or reference method. |
| Interferences (Icterus, Hemolysis, Lipemia, Biotin) | Recovery of positive samples within ± 20% of initial value. | Unaffected by icterus ( |
§ 866.3780
Toxoplasma gondii serological reagents.(a)
Identification. Toxoplasma gondii serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies toToxoplasma gondii in serum. Additionally, some of these reagents consist of antisera conjugated with a fluorescent dye (immunofluorescent reagents) used to identifyToxoplasma gondii from clinical specimens. The identification aids in the diagnosis of toxoplasmosis caused by the parasitic protozoanToxoplasma gondii and provides epidemiological information on this disease. Congenital toxoplasmosis is characterized by lesions of the central nervous system, which if undetected and untreated may lead to brain defects, blindness, and death of an unborn fetus. The disease is characterized in children by inflammation of the brain and spinal cord.(b)
Classification. Class II (performance standards).