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Multicenter performance evaluation of the “quanty TOXO (RH region)” kit (Clonit) for molecular diagnosis of toxoplasmosis

Summary

Researchers from seven French hospitals tested a commercial DNA test kit called “quanty TOXO” that detects Toxoplasma gondii, a parasite causing serious infections in pregnant women and people with weakened immune systems. The kit performed well overall, correctly identifying infection in nearly 95% of positive cases and showing no false positives. However, the test sometimes missed infections when parasite levels were very low, suggesting doctors should run tests twice to increase detection chances.

Background

Toxoplasmosis diagnosis in congenital and immunocompromised patients relies on real-time PCR molecular tools. Many commercial kits are available on the market, but independent expert evaluation provides valuable information for selecting high-performance assays. The French National Reference Center for Toxoplasmosis previously evaluated a Clonit PCR assay with poor performance, and now evaluates their new “quanty TOXO (RH region)” kit.

Objective

To evaluate the analytical and clinical performance of the “quanty TOXO (RH region)” PCR assay manufactured by Clonit using a multicenter strategy. The evaluation assessed sensitivity, specificity, linearity, efficiency, and limit of detection across seven French university hospital laboratories.

Results

PCR efficiencies ranged from 95% to 105% with linearity over four log units (R² >0.99). Limit of detection varied from <1 parasite/mL to 1-5 parasites/mL depending on the center. Clinical sensitivity was 94.7% (71/75; 95% CI: 87.1%-97.9%) and specificity was 100% (66/66; 95% CI: 94.5%-100%). Four false negative results were detected despite duplicate amplification.

Conclusion

The “quanty TOXO (RH region)” PCR assay demonstrated satisfactory analytical and clinical performance for toxoplasmosis diagnosis, suitable for routine use even with extraction and amplification techniques not validated by the manufacturer. However, duplicate analysis is recommended to increase detection probability in specimens with low parasitic loads.
  • Published in:Journal of Clinical Microbiology,
  • Study Type:Multicenter Diagnostic Evaluation Study,
  • Source: PMID: 41065361, DOI: 10.1128/jcm.00538-25
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