Analysis of Chest Radiographs of Culture-Positive Legionella Pneumonia in Japan, 1980-1990

We analyzed the initial and follow-up chest radiographs of 28 patients with culture-positive Legionella pneumonia, and developed a scoring system to quantitate the severity of radiological findings for pneumonia. Intrapulmonary shadows were observed on the initial chest radiograph in 26 patients, but pleural effusion was noted in only one. In one patient the initial chest radiograph had probably been obtained too early to reveal any pulmonary change. Alveolar shadows were noted on the initial radiograph in 21 (81%) patients, and interstitial shadows in 5 (19%). In ten (38%) patients shadows were present in both lung fields. Shadows were prominent in the middle and lower lung fields. A cavity was noted in only one patient, and pleural effusion was also noted at some time during the clinical course in 19 (70%). A large amount of pleural effusion was observed in four patients. The average pneumonia severity score was 3.3 in the 9 patients who survived, and 5.1 in the 17 who died (p > 0.05). The mortality rate was 53% in the 17 patients with pneumonia severity score of 5 or less and 89% in the 9 patients with a score of 6 or more (p > 0.05). Twelve patients died within one week after the initial chest radiograph was obtained. There were no differences among patients with community-acquired infection with or without underlying disease and those with nosocomial infection in characteristic and extension of shadow, presence of pleural effusion, or pneumonia score. The chest radiograph of Legionella pneumonia include bilateral shadow findings characteristic, pleural effusion and rapid progression of shadow, and are clinically useful for diagnosis.