Evaluation of a rapid immunochromatographic assay for the detection of Legionella antigen in urine samples.

A new immunochromatographic membrane assay for detecting Legionella pneumophila serogroup 1 antigen in urine samples (Binax Now Legionella Urinary Antigen Test; Binax, USA) was evaluated. Its sensitivity, specificity and level of agreement with the Binax enzyme immunoassay were compared using nonconcentrated and concentrated urine samples. The overall agreement between the two tests was 98.1%; the specificity of both was 100%. The sensitivity of the immunochromatographic assay was 55.5% in nonconcentrated urine and 97.2% in concentrated urine in comparison with the enzyme immunoassay, using concentrated urine as the reference test. This immunochromatographic assay screens successfully for Legionella pneumophila serogroup 1 soluble antigen in concentrated urine samples.