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A.M. FREYDIERE, G. DESCOURS, F. VANDENESCH, G. LINA, S. JARRAUD* Centre Na)onal de Référence des Légionelles, Hospices Civils de Lyon Centre de Biologie et de Pathologie Est Laboratoire de Bactériologie – 59, Boulevard Pinel 69677 Bron, FranceV Comparison of the Sofia Legionella FIA Test (FIA) (QUIDEL, San Diego, CA) to the Binax NOW Legionella Urinary Antigen Card (UAC) (Alere Scarborough, Maine, USA). Objectives - 150 prospective urine samples (US) submitted to our laboratory for Legionella urinary antigen detection and 49 repository US from patients with known legionnaires' disease (LD) stored at −20°C were tested. - Frozen US were tested by FIA and the results were compared to those of concentrated and nonconcentrated US tested simultaneously by the UAC. - Concentration of US was performed by centrifugal ultrafiltration (Amicon Ultra-4; Millipore Corporation, Bedford, Mass). - Any urine sample yielding a positive result was retested after heating at 100°C for 5 min and centrifugation for 15 min at 1000 rpm - US yielding discordant results were tested by the Binax EIA Material and Methods Sofia Legionella FIA Test and Binax NOW Conclusion The Sofia Legionella FIA performed on nonconcentrated urine samples showed performance close to those of the Binax NOW Legionella Urinary Antigen Card performed with concentrated urine samples. However, heating of any positive samples prior to testing is essential to exclude false positive results. On nonconcentrated US, sensitivity of Sofia FIA test appears better than Binax Now Legionella test. Easy to perform, this test offers objective results, operation in a run- now or walk-away mode, hard copy and memory stored results. These features make it valuable to the diagnostic laboratory. On the 199 US tested, FIA andC yielded 146 and 150 negative results and 53 and 49 positive results, respectively. Results and Discussion Poster: 6 BinaxNOW® Legionella (Alere) using concentrated urine + Sofia Legionella FIA Test (Quidel) using nonconcentrated urine 146 0 + 4* 49 We thank the technicians of the Na)onal Reference Center of Legionella for their help in performing the tests. The study was financed by Quidel and InGen. EvaluaOon of the Sofia Legionella FIA a Fluorescent Immunochromatographic Assay in Comparison with the Binax Now Legionella Urinary AnOgen Card 2. Sofia Legionella FIA test employs a lateral-flow immunofluorescence technique interpreted with the SOFIA TM analyzer, which automatically scans the test strip, calculates and reports the result in about 1 minute. 1. Binax NOW test , is a chromogenic immunochromatographic test. A result was considered positive when two lines were visible after 15 min of incubation at room temperature 3. Binax EIA test was performed in case of discrepancy between the results of the 2 tests. A result was considered as positive when the absorbance value was three times the value of the negative kit control. Results of the Sofia Legionella FIA using unconcentrated US compared with the results of the Binax NOW using either concentrated US (Table 1) or nonconcentrated US (Table 2). *The 4 US positive with FIA and negative with UAC yielded a negative result after heating at 100°C for 5 min. None had clinical evidence of Legionella pneumonia and 3 of the 4 were checked with the Binax ELISA and yielded a negative result. There is no visual signal. The reading is performed after 10 minutes of incubation either in the analyzer or on the bench. In Walk Away Mode, the user immediately inserts the Cassette into the Analyzer. The user then returns after 10 minutes to get the test result. BinaxNOW® Legionella (Alere) using nonconcentrated urine + Sofia Legionella FIA Test (Quidel) using nonconcentrated urine 146 0 + 6* 47 *On the 6 discrepant results, 4 corresponded to a false positive diagnosis (negative result after heat treatment) and 2 to a true positive diagnosis (positive after heat treatment). These 2 positive results were also confirmed by Legionella PCR and by Now Binax test on concentrated urine. . Table 1 Table 2
