Legionella urinary antigen in early disease.

The results of Legionella urinary antigen testing were correlated to the interval between onset of disease and sampling of urine in 134 patients in connection with a large outbreak of Legionnaires' disease at a Swedish hospital. In 17 patients with the disease, 5/7 sampled during the first 5 days of illness proved negative in the urinary antigen test. The risk of obtaining negative results during the first days of the disease is emphasized.