In 83 patients who were diagnosed clinically as having atypical pneumonia, Legionella pneumophila was investigated. In all patients anti-L.pneumophila antibodies were investigated by IFA. In 46 patients; DFA, and culture methods were performed for lower respiratory tract specimens(26 sputum, 17 bronchoalveolar lavage fluid, 3 transtracheal aspirate) and urinary antigen was investigated by ELISA.

Totally in 11 (13.2%) patients legionellosis was detected. In 10 of these 11 patients seroconversion was detected. Amongst 9 patients for whom all tests were performed, diagnosis was made by DFAand seroconversion in 4 patients, by IFAin 3 patients, by DFAin 1 patient and by all tests in 1 patient.