Legionella pneumophila

Legionella pneumophila

Legionella pneumophila (pronounced lee-juh-nel-uh new-mo-fi-luh) is a thin, aerobic, pleomorphic, flagellated, non-spore-forming, Gram-negative bacterium of the genus Legionella.

Etymology

The name Legionella pneumophila is derived from the outbreak in 1976, when many people who went to a Philadelphia convention of the American Legion suffered from this disease, hence Legionella. Pneumophila is derived from the Greek words pneumon (lung) and philos (loving), indicating it has a predilection for the lungs.

Description

Legionella pneumophila is the primary human pathogenic bacterium in this group and is the causative agent of Legionnaires' disease, also known as legionellosis. The bacteria are found in various freshwater environments, causing pneumonia when inhaled from contaminated water sources such as cooling towers or showers.

Pathogenesis

Legionella pneumophila infects and replicates within alveolar macrophages and human lung epithelial cells. The bacteria use a specialized secretion system, the type IV secretion system, to inject effector proteins into the host. These effectors modulate host cell functions to aid bacterial survival and replication.

Diagnosis

Diagnosis of Legionella pneumophila involves culturing the bacteria from the patient's sputum, or detecting the bacteria's DNA or antigens in the patient's urine or serum.

Treatment

Treatment typically involves antibiotics such as macrolides, quinolones, or rifampin.

Prevention

Prevention of infection involves controlling the proliferation of the bacteria in water systems.

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