Incidence and clinical features of community-acquired legionellosis in hospitalized patients

In a two-year prospective study of patients hospitalized because of community-acquired pneumonia, the incidence of legionellosis was found to be 3.8% (17/442 cases). After S. pneumoniae, M. pneumoniae and influenzae viruses, legionellae were the fourth most frequently identified pneumonia agents. We evaluated the clinical data from 41 cases with legionellosis, 17 diagnosed in this prospective study and 24 prior to the study. The age range of all patients (22 women, 19 men) was 24-78 yrs (median 61.3 yrs), 14 of 41 cases (34.1%) had extrapulmonary organ involvement. Twelve patients (29.3%) died. The fatality rate was 4.5% (1/22 cases) in patients treated with erythromycin, and 57.9% (11/19 cases) in patients treated with other antibiotics. Antibiotics effective in legionellosis should be added to the routine therapy of community-acquired pneumonia when this aetiology can not be excluded.