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Test Code LEGION U Legionella Antigen, Urine

Reporting Name

Legionella Ag, U

Useful For

An adjunct to culture for the presumptive diagnosis of past or current Legionnaires disease (Legionella pneumophila serogroup 1)

Advisory Information

This assay has been validated using urine specimens only. For serum specimens, see SLEG / Legionella pneumophila (Legionnaires Disease), Antibody, Serum.


Other specimen types (eg, plasma or body fluids) that may contain Legionella antigen have not been tested.

Specimen Required

Container/Tube: Plastic, 10-mL urine tube (T068)

Specimen Volume: 0.5 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.

3. Excessively bloody or very turbid specimens containing protein, cells, or particulates will be cancelled. They can inhibit the function of the test.

4. Centrifuging to remove particulates is not approved.

5. Specimens with any dyes or unnatural color are not acceptable and will be canceled.

Specimen Type


Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 7 days
  Frozen  14 days
  Ambient  24 hours

Day(s) and Time(s) Performed

Monday through Friday; 12 p.m.

Seattle Children's Hospital Note:

TAT: 3 days

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Immunochromatographic Membrane Assay

Method Description

The BINAXNOW Legionella Urinary Antigen Test is an immunochromatographic membrane assay to detect Legionella pneumophila serogroup 1 soluble antigen in human urine. Rabbit anti-L pneumophila serogroup 1 antibody (the patient line) is adsorbed onto nitrocellulose membrane. Goat-antirabbit IgG (the control line) is adsorbed onto the same membrane as a second stripe. Rabbit anti-L pneumophila serogroup 1 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.


To perform the test, a swab is dipped into the urine specimen, removed, and then inserted into the test device. Reagent A is added from a dropper bottle. The device is then closed, bringing the specimen into contact with the test strip. L pneumophila serogroup 1 urinary antigen captured by immobilized anti-L pneumophila serogroup 1 antibody reacts to bind conjugated antibody. Immobilized goat-antirabbit IgG also captures visualizing conjugate, forming the control line. A positive test result is visually read in 15 minutes or less depending on the concentration of antigen present in the urine specimen. A negative result, read in 15 minutes, indicates that L pneumophila serogroup 1 antigen was not detected in the urine specimen.


The test is interpreted by the presence or absence of visually detectable pink-to-purple colored lines. A positive result will include the detection of both a patient and a control line, while a negative assay will produce only the control line. Failure of the control line to appear, whether the patient line is present or not, indicates an invalid assay.(Package insert: BINAXNOW Legionella Urinary Antigen Test, Binax Inc, Portland, ME, 1999)

Reference Values


Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
LAGU Legionella Ag, U 32781-7


Result ID Test Result Name Result LOINC Value
81268 Legionella Ag, U 32781-7

Reject Due To


Mild reject; Gross reject






Turbid reject, Colored reject


If not ordering electronically, complete, print, and send a Microbiology Test Request Form (T244) with the specimen (