Legionella pneumophila and S pneumoniae were the main causes of community-acquired pneumonia with respiratory failure. Legionnaires’ disease often is a severe illness and its frequency seems to be higher when only patients with severe pneumonia are evaluated.
Laboratory diagnosis of Legionnaires’ disease usually is made by examination of respiratory specimens by direct immunofluorescence, indirect immunofluorescence serologic studies and by isolation of L pneumophila.’25 We have not evaluated direct immunofluorescence because we did not use it routinely in all patients. N£w diagnosticj systems such as ujrinary antigen detection by enzyme-linked immunoabsor-bent assay or radioimmunoassay* and gen-probe detection for L pneumophila are not currently available in our hospital.
We could isolate L pneumophila in 70 percent of our patients. This high percentage is probably related to the fact that all sputum samples of all patients with community-acquired pneumonia are spread in BCYE-alpha media, even when sputum is not microscopically purulent and has more than 25 epithelial cells per low-power field. If pneumonia due to L pneumophila is suspected, it is important that the laboratory.