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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Legionella Urinary Ag

Test Code(s): LUAG / GM4910

CPT Code(s): 87449

Methodology: Immunochromatographic Assay

Clinical Significance: Detects the presence of Legionella pneumophila serogroup 1 antigen in urine.

Days Performed: Mon-Fri.

Turnaround Time: Stat: Not available stat.
Routine: Up to 3 days.

Specimen Requirements

Specimen: Urine

Collection Container: Preferred: Sterile screw cap container

Collection Volume: Preferred: 1 mL
Pediatrics: 1 mL

Sample Analyzed: Urine aliquot

Specimen Transport: Urine may be transported at room temperature for up to 24 hours following collection. Specimen may also be refrigerated up to 14 days or frozen for longer periods. Boric acid may be used as a preservative. Transport specimen to UWHC Microbiology (B4/231).

Unacceptable Criteria: LIMIT: One specimen every 7 days. Specimens that are inappropriately transported are not acceptable.

Stability: Ambient: 24 hours
Refrigerated: 14 days
Frozen: Freeze if sample will not be assayed within 14 days.


Expected Results:


Test Limitations:

Test will not detect infections caused by other Legionella pneumophila serogroups or other Legionella species.

This test in not validated for diuretic urines nor outpatient population.

Additional Information:

Antigen excretion may begin as early as 3 days after onset of symptoms and persist for up to one year.


A negative result indicates a presumptive negative for Legionella 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, the antigen may not be present in urine in early infection, or the level of antigen present in the urine may be below the detection limit of the test.


Culture is recommended to detect causative agents other than Legionella pneumophila serogroup 1 and to recover L. pneumophila serogroup 1 when antigen is not detected in the urine.


A positive result suggests current or past infection and is not definitive for infection without other supporting evidence.

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