RESUMO
BACKGROUND: Risk factors associated with LP are frequent in patients older than 60 years old who are hospitalized with pneumonia. The aim of the study was to define the incidence, epidemiological and clinical features of LP in this age group in Northern Israel. STUDY DESIGN: The study was prospective and conducted for one year during the period 1.6.1999-31.5.2000. All patients older than 60 years who were hospitalized with community-acquired or nosocomial pneumonia were tested for legionella infection by the urine antigen test (which identifies Legionella pneumophila type I and 14 other Legionella serotype antigens). Data was obtained from each patient regarding risk factors and clinical feature of the disease. The data of patients with LP was compared on a 1:2 ratio to data obtained from a control group of patients with non LP according to age, sex, and week of admission. RESULTS: During the study period 202 patients and 38 patients were hospitalized with community-acquired or nosocomial pneumonia respectively. Overall, 8/240 patients (3.3%) were found to suffer from LP. All patients with LP had community-acquired pneumonia with an incidence of 8/202 (4%). Six of the 8 patients (75%) with LP were hospitalized during June-September. Significant clinical findings in patients with LP as compared to those in the control group, respectively, were: severity score, history of smoking, mental status alteration, respiration rate over 30/minute, respiratory acidosis, hypoxia, and need for mechanical ventilation (P < 0.05 in all). All patients with LP were treated with macrolides, however the death rate was 50% vs 0% in the control group (p < 0.001). CONCLUSIONS: In northern Israel, LP is infrequent among patients older than 60 years hospitalized with pneumonia. The disease occurs mostly during the summer in patients with community acquired pneumonia. Patients with LP had unique and more severe clinical features and the death rate was very high inspite of appropriate therapy.