Diagnostic experience in two cases of legionellosis

Sera of 30 patients with atypical pneumonia were tested for antibodies against the representative strains of Legionella pneumophila 1-6 serogroups and 4 species of legionella-like organisms. Investigations were carried out with indirect immunofluorescence assay. The sera of 2 patients gave a titre of 2048 and 1024 with serogroup 5 and 4, respectively. The high antilegionella IgM titres were indicative of recent infections. Legionellae were not detected in transtracheal aspirate and in autopsy material.