Legionella pneumophila
Ajay Rao

Legionella are usually found in non-marine aquatic environments and can be found in high numbers if the water is polluted. Legionella, in its natural environment, is found living within another organism. They are unique in that they can grow and reproduce even with great variation in temperature. Optimum levels of growth occur from 25 – 40 degrees celsius, however, Legionella have been known to grow anywhere from 5 to 63 degrees celsius (Microbe Wiki). In addition to temperature, areas with high rust and algae levels provide iron and nitrogen which makes for a good place for the bacterium to live.

It is a gram negative bacterium, but it is difficult to distinguish this through the staining process. The outermost level of the cell membrane contains lipopolysaccahride content which leaves the bacteria with little to no pigment. L. pneumophila has an interesting structure being either a rod of coccoid shape and is pleomorphic (it will change its shape several times over its life). They are very flat and have one to three flagella to aid in movement (MicrobeWiki). During its lifespan, L. pneumophila does not create spores and has 2 phases, one of these is the replicative phase which pretty much reflects what occurs during this time of its life, replication occurs and the bacterium has low toxicity levels. The second phase is where L. pneumophila makes its name. The bacterium shortens and thickens and increases its toxicity level, this is when its causes Legionnaire’s disease.

Legionella pneumphila, as stated before, received its name from causing an outbreak of pneumonia at an American Legion convention. The most common way of becoming contaminated is by inhalation. The illness can easily be treated and young people who have strong immune systems can actually fight off the bacteria. If inhalation occurs, the bacterium will travel to the lungs and come into contact with an alveoli macrophage. If the macrophage eats the microbe then it will stop the fusion of the monoctye and lysosome. If this occurs, then the pneumophila can reproduce and spread to other cells in the body.

Works Cited

"Legionella." Microbe Wiki. 16 Aug. 2006. Kenyon College. 27 Jan. 2007 <http://microbewiki.kenyon.edu/index.php/Legionella>.

"Legionella pneumophila." 25 Jan. 2007 <http://s99.middlebury.edu/BI330A/projects/Cocchiaro/>.

"Legionella pneumophila." Wikipedia. Wikimedia Foundation, Inc. 28 Jan. 2007 <http://en.wikipedia.org/wiki/Legionella_pneumophila>.

*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.


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