[Community-acquired Legionella pneumonia : data from the CAPNETZ study].

Legionella are present in the environment as well as in biofilms of water installation systems. Most Legionella live in amoebae. More than 51 different species of Legionella have been identified; however, most pneumonias are caused by Legionella pneumophila serogroup 1. Legionnaire's disease has an incidence of about 4% in Germany. Most cases of Legionnaire's disease are sporadic. Microbiological identification of Legionella can be achieved by cultivation of Legionella spp. on specific media, performing of Legionella-specific PCR from respiratory samples, or Legionella urinary antigen testing. Patients with severe underlying diseases, patients receiving immunosuppression, and patients who are heavy smokers have a predisposition to Legionnaire's disease. Men are significantly more often affected. Whereas outpatients show a mild clinical course, mortality for hospitalized patients is 11.2%. It can be assumed that only a minority of cases of Legionnaire's disease is recognized and reported in Germany.