Elevation of serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase, alkaline phosphatase and serum creatinine levels was found more frequently in Legionnaires’ disease than in pneumococcal pneumonia (p<0.05). The prevalence of hyponatremia and microscopic hematuria was similar in both groups. An initial chest radiograph showed alveolar infiltrates in all patients; in 20 percent, multiple lobes were involved and 13 percent had bilateral infiltrates. Pleural effusions were seen in 7 percent of cases. At presentation there were no differences in the extent of pulmonary involvement as seen on chest roentgenograms of patients with Legionnaires’ disease and pneumococcal pneumonia. However, progression with involvement of another lobe occurred more frequently in pneumonia caused by L pneumophila than in pneumococcal pneumonia (p<0.05).
Legionella pneumophila serogroup 1 was isolated in 19 patients and serogroup 3 in two patients. Of these, in 17 cases the bacterium grew in sputum. In four patients the bacteria were cultured from specimens obtained by bronchoscopy. In eight of the 17 cases (47 percent) in which L pneumophila was isolated from sputum it had more than 25 epithelial cells per low-power field, so it did not meet the Murray and Washington criteria for inclusion in their group 5.