BinaxNow Legionella Urinary Antigen Test

The BinaxNOW® Legionella Urinary Antigen Test is an in vitro rapid immunochromatographic assay for the qualitative detection of Legionella pneumophila serogroup 1 antigen (L. pneumophila serogroup 1 antigen) in urine specimens from patients with symptoms of pneumonia. It is intended to aid in the presumptive diagnosis of Legionella infection (Legionnaires’ disease) caused by L. pneumophila serogroup 1 in conjunction with culture and other methods.

Principle:

The BinaxNOW® Legionella Urinary Antigen Test is an immunochromatographic membrane assay to detect Legionella pneumophila serogroup 1 soluble antigen in human urine. Rabbit anti-Legionella pneumophila serogroup 1 antibody, the patient line, is adsorbed onto nitrocellulose membrane. Control Line antibody, is adsorbed onto the same membrane as a second stripe. Both rabbit anti- Legionella pneumophila serogroup 1 antibodies and anti-species antibodies are conjugated to visualizing particles that are dried onto an inert fibrous support. The resulting conjugate pad and the striped membrane are combined to construct the test strip. This test strip and a well to hold the swab specimen are mounted on opposite sides of a hinged, book-shaped test device.

Procedure:

• Do not remove device from pouch until test sample has reached room temperature.
• Bring patient urine and/or liquid urine control(s) to room temperature (59- 86°F, 15-30°C). Remove device from its pouch just before use and lay flat.
• Dip a Binax swab into the urine sample to be tested, completely covering the swab head. If the swab drips, touch swab to side of urine container to remove excess liquid.
• There are two holes on the inner right panel of the device. Insert swab into the BOTOM hole (swab well). Firmly push upwards so that the swab tip is fully visible in the top hole. DO NOT REMOVE SWAB.
• Hold Reagent A vial vertically, ½ to 1 inch above the device. Slowly add two (2) free falling drops of Reagent A to the BOTTOM hole.
• Immediately peel off adhesive liner from the right edge of the test device.
• Close and securely seal the device. Read result in window 15 minutes after closing the device. Results read beyond 15 minutes may be inaccurate. However, some positive patients may produce a visible sample line in less than 15 minutes.

Interpretation:

• A negative sample will give a single pink-to-purple colored Control Line in the top half of the  window, indicating a presumptive negative result. This Control Line means that the detection part of the test was done correctly, but no L. pneumophila serogroup 1 antigen was detected. 
• A positive sample will give two pink-to-purple colored lines. This means that antigen was detected. Specimens with low levels of antigen may give a faint Sample Line. Any visible line is positive. 
• If no lines are seen, or if just the Sample Line is seen, the assay is invalid. Invalid tests should be repeated. If the problem persists, contact Binax Technical Service. 

Reporting:

• Positive - Presumptive positive for L. pneumophila serogroup 1 antigen in urine, suggesting current or past infection. 
• Negative - Presumptive negative for L. pneumophila serogroup 1 antigen in urine, suggesting no recent or current infection. Infection due to Legionella cannot be ruled out since other serogroups and species may cause disease, antigen may not be present in urine in early infection, and the level of antigen present in the urine may be below the detection limit of the test.