[Legionelloses].

Abstract

Legionnaire's disease is a life-threatening disease, observed in up to 15% of patients with pneumonia. Legionella pneumophila serogroup 1 is the most frequently implicated species among the genus Legionella. Legionella can cause two clinical pictures: Legionnaire's disease, a severe pneumonia, or Pontiac fever, a self-limiting disease. The attributable mortality of Legionnaire's disease is between 5-30%. Patients with typical Legionnaire's disease present with fever > 39 degrees C, cough and flu-like symptoms that do not respond to betalactam antibiotics. Neurological disorders may accompany severe cases. Laboratory findings include non-purulent sputum, increased liver enzymes and hyponatriemia. However, most patients do not fulfill all of these signs, symptoms and laboratory finding. Patients present with Legionella are frequently missed in the microbiology laboratory because clinicians do not ask for the specimen to be tested for Legionella. Established risk factors for Legionnaire's disease are chronic obstructive pulmonary disease (COPD), smoking and immunosuppressive therapy. New diagnostics tools such as the Legionella antigen in the urine, as well as PCR of a sputum sample allow rapid and accurate diagnosis. Such investigations are recommended for patients with severe pneumonia and those requiring hospitalization. State-of-the-art treatment includes a second generation macrolide, or alternatively, newer quinolones which are recommended as first-line drug for transplant patients. Prevention of Legionella requires a multi-faceted approach: The warm water should be kept at 60 degrees C in the boiler; the warm water should reach 50 degrees C at the faucet two minutes of opening the handle and the shower heads should be preferably made of stainless steel. In the hospital, the warm water supply should be free of Legionella at least for severely immunocompromised patients.