The protean manifestations of Legionnaires' disease.

The protean manifestations of Legionnaires' disease are described in an analysis of 12 sporadic cases. Two forms of the disease have been delineated. One variant (Group A) consisted of six patients who had a mild form of non-progressive pneumonia with minimum extra-pulmonary involvement. Six patients (Group B) were differentiated by rapidly progressive pulmonary infiltrates, severe hypoxia and respiratory failure, plus a higher frequency of band neutrophils and extra-pulmonary manifestations. Particularly notable were evidence of severe myositis (elevated creatinine phosphokinase and lactate dehydrogenase), anaemia, and neurological findings which included alterations in the sensorium, meningitis, and convulsions. Cerebrospinal fluid (CSF) abnormalities were seen frequently in patients with neurological manifestations, and necropsy findings in one patient suggested that the Legionnaires' bacillus was capable of producing a fatal leucoencephalitis. Renal findings included haematuria, proteinuria and oliguric renal failure. Hepatic transaminases (SGPT, SGOT) were elevated in six patients and serum bilirubin was abnormal in five. Alkaline phosphatase values were normal to minimally elevated. The gastrointestinal symptoms commonly considered to be a frequent initial manifestation of Legionnaires' disease were rare in this series. Recommendations for instituting empirical therapy, based upon recognition of a clinical syndrome which should suggest the diagnosis of Legionnaires' disease, are included.