Method comparison of the ImmuView L. pneumophila and L. longbeachae Urinary Antigen test with BinaxNOW Legionella Urinary Antigen Card for the detection of L. pneumophila serogroup 1 antigen in urine.

We compared the clinical performance of the ImmuView L. pneumophila and L. longbeachae Urinary Antigen test (SSI Diagnostica A/S, Hillerod, Denmark) to the BinaxNOW Legionella Urinary Antigen Card (Binax, Abbott, Lake Buff, IL) using urine specimens from patients suspected of having pneumonia. In total, 100 frozen urine samples (derived from 50 Legionella cases and 50 non-cases) were analyzed with both tests, as well as 200 non-frozen prospectively collected samples. For urine samples of five Legionella cases and two non-Legionella cases, the analytical sensitivity (limit of detection) and repeatability were examined. The urine samples of the five Legionella cases were diluted with urine samples that tested Legionella urinary antigen negative with both tests. The analyses of the 100 frozen samples resulted in a sensitivity and specificity of both the ImmuView and the BinaxNOW of 96.0% (48/50) and 100% (50/50). Of the 200 non-frozen samples, there were three samples that in both tests showed a positive result for L. pneumophila. The analyses of reproducibility showed that for the 34 (diluted) samples that were tested at two consecutive times, 33 samples showed a consistent result for both the ImmuView and the BinaxNOW test (Cohen9s kappa9s: 0.916 and 0.928). In addition, the ImmuView test may have detected two L. longbeachae positive urine samples, although other diagnostic tests could not confirm this. Both ImmuView and BinaxNOW showed high sensitivity and specificity for the detection of L. pneumophila serogroup 1 antigen in urine samples from clinical patients with a suspected lower respiratory tract infection.