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

A new immunochromatographic membrane assay for detecting Legionella pneumop hila serogroup 1 antigen in urine samples (Binax Now Legionella Urinary Ant igen Test; Binax, USA) was evaluated. Its sensitivity, specificity and leve l of agreement with the Binax enzyme immunoassay were compared using noncon centrated 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 co ncentrated urine as the reference test. This immunochromatographic assay sc reens successfully for Legionella pneumophila serogroup 1 soluble antigen i n concentrated urine samples.