Legionella – Urine antigen

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

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 following testing options are available for Legionnaires disease: PCR and culture (lower respiratory specimens), or Urine Antigen Test (urine specimen). This page is for information specific to Urine Antigen Test (urine specimen) for Legionella.

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

Updates

Added special instructions for submitting specimens related to outbreak investigation.
Added possible test results and interpretation under ‘Test Methods’
Alignment of reporting instruction for Legionella - positive specimen to the Medical Officer of Health as per Ontario Health Protection and Promotion Act under ‘Reporting’

*Uncontrolled print copy. Valid only on day of print: 24 April 2024.

Testing Indications

Refer to the testing indications found in Legionella – Respiratory–PCR and Culture .

Legionella Urine Antigen testing is used for rapid diagnosis of Legionnaire’s disease consequent to Legionella pneumophila serogroup 1 infection.

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 this information may result in rejection or testing delay.

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 persist for up to 1 year afterwards.

Limitations

This test will only detect infections caused by Legionella pneumophila serogroup 1. It will not detect infections caused by non-serogroup 1 Legionella pneumophila or 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’s laboratory on ice packs. All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.

Special Instructions

For Outbreak Investigation:

Contact your local Public Health Unit if you suspect an outbreak of Legionella.

Specimens that are part of an outbreak investigation should have the Public Health Unit assigned outbreak number on the label as well as indicated on the requisition. For any cluster investigation, please contact PHO’s laboratory Customer Service at 416-235-6556/1-877-604-4567 regarding assigning an investigation number prior to sample submission.

Respiratory specimens must be submitted to enable genomic analysis such as Sequenced Base Typing to support outbreak investigations, please 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 laboratories, 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 samples please notify customer service to ensure the sample is on the next available run.

Test Methods

Legionella specimens are tested by a commercial Binax ICT (Abbott) .

The Binax test is >70% sensitivity and >99% specific. 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 antigenis 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: https://www.cdc.gov/legionella/clinicians/diagnostic-testing.html