Abstract :
[en] Validation at CHU Liège of Diasorin urinary antigen tests (LIAISON® XL, CLIA) for Streptococcus pneumoniae and Legionella pneumophila. 100% sensitivity and specificity, CV < 3%, perfect concordance with BinaxNOW® (κ = 1.0), and broader detection spectrum (pneumococcal CWPS; Legionella serogroups 1–15).
References of the abstract :
Silent Invasion: Pathogens in the Garden of BreathSilent Invasion: Pathogens in the Garden of Breath
Background. Community-acquired pneumonia (CAP) remains a major diagnostic challenge: no pathogen is identified in 62% of hospitalized cases. Among bacterial agents, Streptococcus pneumoniae and Legionella pneumophila play a central role, with sharply rising incidence in Europe between 2013 and 2023 (+64% for invasive pneumococcal disease, +165% for legionellosis).
Objective. To validate, according to the SH GTA 04 criteria (Scope B – qualitative), the Diasorin Streptococcus pneumoniae and Legionella pneumophila urinary antigen tests on the automated LIAISON® XL platform (CLIA technology), and to compare them with the reference immunochromatographic tests (BinaxNOW® – Alere/Abbott).
Methods. Comprehensive evaluation including: analytical sensitivity and specificity, diagnostic concordance, intra- and inter-assay repeatability, robustness, limit of detection, semi-quantitative curve (Log10 CFU/mL vs Index), external quality control (UK NEQAS), and interpretation thresholds.
Results.
Analytical performance: 100% sensitivity and specificity for both tests; CV < 3%; perfect concordance with BinaxNOW® (Cohen's κ = 1.0).
Limits of detection: ~5 × 10⁴ CFU/mL for S. pneumoniae; ~3.75 × 10⁴ CFU/mL for L. pneumophila.
Strong log-linear correlation between index value and bacterial load (R² = 0.989 and 0.997).
Expanded detection spectrum: coverage of multiple pneumococcal serotypes via CWPS (>95% vs ~50%) and of Legionella serogroups 1–15 (~100% vs ~87% limited to serogroup 1), representing an estimated diagnostic gain of +45% and +13%, respectively.
Conclusion. The Diasorin urinary antigen tests meet all validation criteria and offer a clear clinical advantage: broader detection, full automation, enhanced reproducibility, and semi-quantitative potential. Particularly useful in atypical, severe, post-vaccination, or culture-negative pneumonia, they entered routine diagnostic use at CHU Liège on April 16, 2025.
Perspectives. Molecular characterization of isolated strains to refine specificity; clinical studies on the prognostic value of the index (initial severity, therapeutic response, early relapse detection).
