LEGIONELLA PNEUMOPHILA ANTIGEN, URINE
- LEGIONELLA PNEUMOPHILA ANTIGEN, URINE
- Start Date
- Expiration Date
- CPT Codes
- Reference Test
- ATLAS Test Code
- Transport Info
- Fasting Required?
- Patient Instructions
- Reference Range
< 3.0 Index: Presumptive negative for L. pneumophila serogroup 1 antigen in urine, suggesting no recent or current infection. Legionnaires' disease cannot be ruled out since other serogroups and species may also cause disease.
≥ 3.0 Index: Presumptive positive for the presence of L. pneumophila serogroup 1 antigen in urine, suggesting current or past infection.
Enzyme Immunoassay (EIA)
L. pneumophila is estimated to be responsible for 80-85% of reported cases of Legionella infections with the majority of the cases being caused by L. pneumophila serogroup 1. Current laboratory methods for the detection of pneumonia caused by L. pneumophila require a respiratory specimen (e.g., expectorated sputum, bronchial washing, transtracheal aspirate, lung biopsy) or paired sera (acute and convalescent) for accurate diagnosis. These techniques include Legionella culture, direct fluorescent antibody, and indirect fluorescent antibody. All of these methods rely on either obtaining an adequate respiratory specimen for sufficient sensitivity or collecting sera at a 2-6 week interval. Unfortunately, one of the presenting signs of patients with Legionnaires' disease is the relative lack of productive sputum. This necessitates in many patients the use of an invasive procedure to obtain a respiratory specimen. Diagnosis by serological techniques is usually retrospective.In 1979, Berdal showed that a specific soluble antigen was present in the urine of patients with Legionnaires' disease. The presence of specific antigen in urine makes this an ideal specimen for collection, transport, and subsequent detection. Excretion of Legionella antigen in urine may vary depending on the individual patient and his or her underlying illness or treatment. Some individuals excrete antigen for an extended period of time, so that a history of a recent respiratory illness compatible with Legionnaires' disease should be sought. Early treatment with appropriate antibiotics may also decrease antigen excretion in some individuals.This assay is for L. pneumophila serotype 1 only, so a negative test does not rule out legionellosis due to other serotypes or species. A positive test may indicate either recent infection or continued antigen shedding from a more remote infection.