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Legionella is a genus of gram-negative bacteria that can be seen using a silver stain or grown in a special media that contains cysteine, an amino acid.It is known to cause legionellosis [3] (all illnesses caused by Legionella) including a pneumonia-type illness called Legionnaires' disease and a mild flu-like illness called Pontiac fever. [3]
Legionella pneumophila, the primary causative agent for Legionnaire's disease, is an aerobic, pleomorphic, flagellated, non-spore-forming, Gram-negative bacterium. [1] [2] L. pneumophila is a intracellular parasite that preferentially infects soil amoebae and freshwater protozoa for replication.
Legionella spp. enter the lungs either by aspiration of contaminated water or inhalation of aerosolized contaminated water or soil. In the lung, the bacteria are consumed by macrophages, a type of white blood cell, inside of which the Legionella bacteria multiply, causing the death of the macrophage. Once the macrophage dies, the bacteria are ...
Legionella has been shown to survive inside of an encysted amoeba host in chlorine treated water, and can release from the host in respirable vesicles when treated with biocides, with each vesicle possibly containing hundreds of legionella bacteria spread by aerosolized water. [9]
Temperature affects the survival of Legionella as follows: [93] 70 to 80 °C (158 to 176 °F): Disinfection range; At 66 °C (151 °F): Legionellae die within 2 minutes; At 60 °C (140 °F): They die within 32 minutes; At 55 °C (131 °F): They die within 5 to 6 hours; Above 50 °C (122 °F): They can survive but do not multiply
Since that time, other species of Legionella that cause Pontiac fever have been identified, most notably in New Zealand, in 2007 where Legionella longbeachae was discovered. The New Zealand outbreak also marked the first time Pontiac fever had been traced to potting soil. [citation needed]
Like other Legionella species, person-to-person transmission has not been documented, but unlike other species, the primary transmission mode has not been proven, but likely is inhalation or aspiration of dust from contaminated compost or soil that contains the organism causing legionellosis. [8]
Caused by bacteria belonging to genus Legionella (90% of cases caused by Legionella pneumophila) Legionella is a very common organism that reproduces to high numbers in warm water; [18] but only causes severe disease when aerosolized. [19] Pontiac fever produces milder symptoms resembling acute influenza without pneumonia.