Evaluation of the Bartels Legionella Urinary Antigen enzyme immunoassay

The Bartels Legionella Urinary Antigen enzyme immunoassay (Intracel, USA) is intended for the presumptive diagnosis of past or current Legionnaires' disease by qualitative detection of Legionella pneumophila serogroup 1 antigen in human urine. This test was evaluated using single urine samples collected from 349 patients with lower respiratory tract infection of known aetiology. Specificity was estimated as 100% (181 samples, 95% CI: 98%-100%); sensitivity for Legionella pneumophila serogroup 1 was 98.8% (167 samples, 95% CI: 95.7%-99.9%). Assessing assay results using a Visual Interpretation Card provided by the manufacturer in place of a photometer gave rise to one false-positive result among the 78 control samples examined. Providing the endpoint of this assay is determined photometrically, the Bartels Legionella Urinary Antigen enzyme immunoassay appears to be a highly specific and sensitive kit for the diagnosis of infection caused by Legionella pneumophila serogroup 1.