Legionella – Urine antigen

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Background
This page provides information on urine testing for Legionella antigen at Public Health Ontario (PHO). Legionella is the causative agent of Legionnaires’ disease.

The available testing options for Legionnaires disease include PCR and culture (performed on lower respiratory specimens), and Urine Antigen Test (UAT) using urine specimen. This page is for the detection of Legionella antigen in urine.

For information regarding other testing options, refer to the following PHO webpages:

Updates

Added best practice guidance on the recommended diagnostic tests for Legionnaire’s disease. Refer to the testing indication section below.

* Copie d'impression non contrôlée. Valide uniquement le jour de l'impression : 16 janv. 2026.

Testing Indications

Best practice for the laboratory diagnosis of Legionnaires’ disease includes the collection and submission of both a lower respiratory specimen(s) and urine, concurrently. UAT allows for the rapid diagnosis of L. pneumophila Serogroup 1. Culture of respiratory specimens allows for the identification of additional species and serogroups. Respiratory specimens are essential, regardless of UAT results, for sequencing, a critical tool during outbreak investigations, in order to link cases to one another and to identify potential environmental sources.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
Urine Antigen Test	General Test Requisition	Urine specimens collected during acute phase of illness	2.0 mL	Sterile container

Submission and Collection Notes

Complete all fields of the General Test Requisition, including:

Test(s) requests and indications for testing such as travel and healthcare exposure
Patient setting/specimen information
Outbreak or investigation number if applicable
Indicate symptoms and date of onset

Label the specimen container(s) with the patient’s first and last name, date of collection, and one other unique identifier, such as the patient’s date of birth or Health Card Number. Failure to provide the required information may result in rejection or testing delay. For additional information see: Criteria for Acceptance of Patient Specimens.

Timing of Specimen Collection

Specimens collected during acute phase of illness are preferred. Antigen excretion may begin as early as 3 days after onset of symptoms and may persist for 6 months to 1 year.

Limitations

This test only detects infections caused by Legionella pneumophila Serogroup 1. It does not detect infections caused by non-serogroup 1 Legionella pneumophila nor any non-pneumophila Legionella species.

Storage and Transport

Specimens should be stored at 2-8°C or at -10°C to -20°C following collection and shipped to PHO on ice packs. All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.

Special Instructions

Specimens that are part of an outbreak should have the Public Health Unit’s assigned outbreak number on the label AND the requisition.

For any cluster investigation, please contact PHO Laboratory Customer Service at 416-235-6556 or 1-877-604-4567 to obtain an investigation number prior to sample submission.

Outbreak and investigation numbers, as appropriate, MUST be documented on all specimens submitted related to the outbreak or investigation, as well as on the requisition.

NOTE: Respiratory specimens are required for molecular analyses (e.g., Sequence- Based Typing) and are therefore critical during outbreaks or cluster investigations. If submitting a urine specimen for UAT, include a respiratory specimen for PCR, culture and sequencing. Refer to Legionella – Respiratory – PCR and Culture for information on testing respiratory specimens for Legionella.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

The Legionella Binax Urine Antigen Test is set up daily, Monday to Friday at PHO’s laboratory, Toronto and Kingston locations.

Turnaround time is up to 2 days from receipt by PHO.

Stat and Critical Specimens Testing

STAT testing is not available; however, for critical specimens please notify PHO Laboratory Customer Service to ensure the sample is on the next available run.

Test Methods

Specimens are tested using immunochromatographic test method (BinaxNOW Legionella Urinary Antigen Card).

The test method has >70% sensitivity and >99% specificity. It detects Legionella pneumophila Serogroup 1 only.

Interpretation

The following table provides possible test results with associated interpretations:

Result	Interpretation	Comments
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, or the level of antigen present in the urine may be below the detection limit of the test.

Reporting

Results are reported to the physician, authorized health care provider (General O. Reg 45/22, s.18) or submitter as indicated on the requisition.

Specimens for which Legionella pneumophila urine antigen is detected are reported to the Medical Officer of Health as per the Ontario Health Protection and Promotion Act, R.S.O. 1990, c. H.7

References

Center for Disease Control and Prevention. Legionella (Legionnaire’s Disease sand Pontiac Fever), Diagnosis, Treatment and Prevention. Available from: Laboratory Testing for Legionella