Immunity against

The Bartels enzyme immunoassay (EIA), Biotest EIA, and Binax NOW immunochromatographic test (ICT) urinary antigen kits for the detection of Legionella pneumophila serogroup 1 were compared using 178 frozen urine samples. When nonconcentrated urine samples were used, the sensitivity levels of both enzyme EIAs were significantly higher than the sensitivity level of the ICT (Bartels EIA, 71.3%; Biotest EIA, 65.1%; Binax NOW ICT, 37% [P < 0.001]). After concentration of the urine samples, no significant differences in sensitivity were found among the three tests.Laboratory diagnosis of Legionella pneumophila infection is performed on the basis of the results of culture growth, direct immunofluorescence, serologic testing, and antigen detection in urine. Since antigen detection in urine has proved to be a sensitive and rapid method for detecting L. pneumophila serogroup 1, this technique has become one of the most used tools for the diagnosis of Legionnaires' disease. The urinary antigen test permits early diagnosis and initiation of appropriate antibiotic therapy (9), and it leads to the recognition of outbreaks of Legionnaires' disease, allowing a rapid epidemiological investigation (10, 11, 13). Currently, there are several commercially available tests (the Binax Legionella urinary antigen enzyme immunoassay [EIA], the Biotest Legionella urine antigen EIA, and the Binax NOW Legionella urinary antigen immunochromatographic test [ICT]) for the detection of L. pneumophila antigen in urine. All of these tests have been previously evaluated, confirming their utility for the diagnosis of Legionnaires' disease (6,12). A wider range of sensitivity has been reported, however, although no research has demonstrated significant differences in sensitivity between these tests. Recently a new EIA (Bartels Legionella Urinary Antigen) for the detection of L. pneumophila serogroup 1 antigen in urine has been developed. We evaluated this new test by comparing its sensitivity to that of two widely used tests: the Biotest EIA and the Binax NOW ICT.A total of 178 urine specimens (obtained from patients with Legionnaires' disease during an outbreak which occurred in Murcia, Spain, in July 2001) were included in the study. The samples were from patients who fulfilled the epidemiological criteria, suffered from symptoms compatible with pneumonia, and showed radiological signs of infiltration and for whom Legionnaires' disease was confirmed either by culture (defined as isolation of L. pneumophila serogroup 1 from respiratory specimens) or serology (defined as a fourfold increase in L. pneumophila serogroup 1 antibody titer in paired sera or, in patients with clinically compatible illness, a high [Ն 256] stationary titer value).During the outbreak, nonconcentrated urine samples were tested within a few hours after receipt by using Biotest EIA (182 were positive and 47 were negative); the samples were then frozen at Ϫ80°C. Samples were retested simultaneously using the Biotest Legionella urine antigen EIA (Biotest AG, Dreieich, Germany), Bi...

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