What type of lab test should we do for a Legionnaires’ diagnosis? If we want to run the Legionella urine antigen by ELISA, can we use urine that has been stored for over 24 hours, or do we need to use fresh urine?
Refrigerate the urine if the test cannot be performed immediately. Test results will decline over time, but may remain positive for up to 3 weeks if the infecting Legionella is L. pneumophila, serogroup 1.