OVERVIEW
What is Legionnaires disease?
It is a bacterial infection caused by legionella bacteria which produces a serious form of pneumonia. It is an infection that occurs in the lower respiratory tract and may require hospitalization. It occurs when people inhale airborne droplets contaminated with the bacteria & has a high mortality (death) rate. Legionella bacteria can also cause Pontiac fever which is a milder and self-limiting illness with flu-like symptoms without pneumonia. Together, legionnaire & pontiac fever is known as legionellosis.
What is Legionella (spot urine) lab test?
This test is used to detect legionella antigen (one of bacterium's proteins) from the urine sample. It is a preferred initial test for Legionnaires disease as it is a rapid way to detect infection. This test only detects one serogroup i.e. Legionella pneumophila which is commonly known to cause the infection.
Why is legionella (spot urine) lab test done?
The test is done:
- As an adjunct with the legionella culture test for proper diagnosis of Legionnaires disease
- As it detects if current or past Legionnaires infection
- This test only detects Legionnaires disease caused by serogroup 1, so for detection of infection with other serogroups/species, a culture & urine antigen test is recommended.
- When patient is suffering from severe pneumonia requiring intensive care
- For immunocompromised patients with pneumonia
- In patients with travel history i.e. travelled away from home within 14 days before onset of symptoms
- In hospitalized patients with healthcare-associated pneumonia (pneumonia with onset ≥48 hours after admission)
- How long does legionella culture test take?
The culture test takes about 10 to 12 days to complete.
- Does legionella testing come under legal requirements?
Legionella testing is considered a legal duty for landlords to assess & control risk of exposure to legionella bacteria.
- What is meant by a positive legionella urine antigen test?
When legionella pneumophila urine antigen test comes positive, it indicates that person is/has been infected with Legionella serogroup 1.
- Can legionella test be done on your own?
By using lateral flow test technology, legionella antigen self-test can be done.
- What are the symptoms of legionella disease?
Its symptoms include high temperature, feverishness/chills, cough, muscle pain, diarrhoea and leading onto pneumonia very occasionally.
INTERPRETATION OF THE RESULTS:
- Positive: It means you are suffering Legionnaires disease currently or have had past infection caused by serogroup 1. Further culture test recommended for confirmation.
- Negative: It either means you don't have the infection, or you have infection with different species/serogroup, or antigen is not present in the detectable limit in the urine. In latter cases, Legionella culture is recommended.
You get tested as it helps identify/diagnose Legionnaires disease, & also detects whether it is recent or past infection.