information:classification, structural:expansion
Legionella pneumophila is an aerobic, pleomorphic, flagellated, non-spore-forming, Gram-negative bacterium of the genus Legionella. L. pneumophila is the primary human pathogen in the genus Legionella. In nature, L. pneumophila infects soil amoebae of the genus Acanthamoeba and freshwater amoeboflagellates of the genus Naegleria. This pathogen is thus found commonly near freshwater environments and invades the unicellular life found in these environments, using them to carry out metabolic functions. L. pneumophila is also the causative agent of Legionnaires' disease, also known as legionellosis. Due to L. pneumophila’s ability to thrive in water, it can grow in water filtration systems, leading to faucets, showers, and other fixtures and then spread through aerosolized water droplets. Once infected, this bacterium can cause pneumonia with symptoms such as fever, delirium, diarrhea, and decreased liver and kidney function. After initial discovery, it was found that Legionella replicates inside amoeba and amoeboflagellates, which suggests that bacteria replicating in environmental protozoa have the ability to exploit signaling pathways in human macrophages.