[The detection of the agent of Legionnaires' disease--a confirmation of Koch's postulates].

The genus Legionella, belonging to the family of Legionellaceae, comprises nowadays seven species, among which Legionella pneumophila might be the most important. The identification of the agent is difficult because L. pneumophila is very pretentious requiring peculiar conditions concerning culture medium, temperature, and time. The initial cultivation will succeed the best in an atmosphere enriched with CO2. The demonstration of serum antibodies will succeed by means of indirect immunofluorescence; recently the micro-agglutination test is vastly applied. The clinical picture of Legionellosis is characterized by an atypical pneumonia with a serious course in most cases. The Pontiac Fever is an illness with milder course than the classical form of Legionellosis. Erythromycin and Rifampicin are the chemotherapeutics of choice.