Legionellosis (legionnaires disease)

Chest | Pulmonology | Legionellosis (legionnaires disease) (Disease)


Description

Legionellosis represents a very serious lung infection caused by the bacteria, Legionella pneumophila. The bacteria may involve other parts of the body including the gastrointestinal tract, the kidneys and central nervous system. Occasionally the kidneys fail requiring dialysis.

Legionella is a bacterium able to survive ambient in a wide range of physicochemical conditions, multiply at temperatures between 20 C and 45 C, can be destroyed at a temperature of 70 C. Its optimal growth temperature is between 35-37 C. Legionella infection can be contacted in the community or hospitals. In both cases the disease may be associated with different types of installations, equipment or buildings. It may appear as focal, isolated or sporadic. If the system is a mechanism producing aerosols, bacteria can spread into the air. Water droplets containing bacteria can remain suspended in the air and inhaled through the respiratory system.

Legionellosis takes two distinct forms: (1)Legionnaires disease, also known as Legion Fever, is the more severe form of the infection and produces high fever and pneumonia; (2) Pontiac fever is caused by the same bacteria but produces a milder respiratory illness without pneumonia that resembles acute influenza. Pontiac fever also has a spontaneous resolution.

Causes and Risk factors

Legionellosis is a potentially fatal infectious disease caused by gram negative, aerobic bacteria belonging to the genus Legionella. Over 90% of legionellosis cases are caused by Legionella pneumophila, a ubiquitous aquatic organism that thrives in temperatures between 25 and 45 C, with an optimum temperature of 35 C.

Units that are most commonly contaminated with Legionella and have been identified as sources of infection are domestic water distribution systems, hot and cold water and equipment cooling by evaporation, such as cooling towers and evaporative condensers of, found both health institutions, as well as in hotels or other buildings.

Diagnosis and Treatment

Imaging, cultures and blood tests are done to establish the diagnosis.

Therapy is dependent on the severity of the disease. Antibiotics are administered. Other therapy includes intravenous fluids, oxygen, and the correction of any blood chemistry abnormalities. Severe cases may require mechanical ventilation and dialysis. ...