[A community outbreak of Legionnaires' disease in Barcelona: clinical and microbiological study].

In February and March 1989 a community-acquired outbreak of legionnaires' disease developed in Barcelona, involving at least 56 patients (48 males and 8 females) with a mean age of 60 years (range 22-87). 70% were smokers, 20% alcohol abusers, 50% had chronic bronchitis and 20% were immunologically depressed. The most common signs and symptoms were: fever (100%), features of lung condensation (77%), cough (51%), stupor (27%), diarrhea (18%), thoracic pain (18%, hyponatremia (53%), increased serum level of hepatic enzymes (44%) or CK (37%), and renal failure (21%). Radiological involvement was bilateral in 30% of cases. In most patients the diagnosis was made by seroconversion (70%). Late seroconversion (between 4 and 14 weeks) was seen in 20 patients, whose age was significantly higher than that of patients with early seroconversion (p less than 0.02). All cases were caused by Legionella pneumophila serogroup 1. Forty-six patients (81%) were admitted to the hospital and 10 (18%) required tracheal intubation. Although all received erythromycin, seven patients died. Hypoxemia, leukopenia, hyponatremia and renal failure were associated with a higher mortality rate. However, after multivariate analysis renal failure appeared as the only independent prognostic variable. Finally, it was concluded that in the community-acquired outbreaks of pneumonia Legionella pneumophila infection should be ruled out.