Legionella pneumophila

Legionella pneumophila
	TEM image of L. pneumophila; TEM image of L. pneumophila
Scientific classification
Kingdom:	Bacteria;
Phylum:	Proteobacteria;
Class:	Gamma Proteobacteria;
Order:	Legionellales;
Family:	Legionellaceae;
Genus:	Legionella;
Species:	L. pneumophila;
Binomial name
	Legionella pneumophila; Brenner DJ, Steigerwalt AG, McDade JE 1979

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This page is about microbiologic aspects of the organism(s). For clinical aspects of the disease, see Legionellosis.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

L.pneumophila is a ubiquitous aquatic organism that thrives in warm environments (32°- 45°C). L. pneumophila is pleomorphic, aerobic, catalase-positive, oxidase-positive, non-spore-forming, non-capsulated, motile, Gram-negative bacteria. Although Legionella is categorized as a Gram-negative bacterium, it stains poorly to Gram stain due to its unique lipopolysaccharide-content in the outer psuedospamodulating leaflet of the outer cell membrane.

Microbiological Classification

Bacteria; Proteobacteria; Gammaproteobacteria; Legionellales; Legionellaceae
Species of Legionella include:

L. pneumophila
L. feeleii
L. sainthelensi

Microbiological Characteristics

L.pneumophila is a ubiquitous aquatic organism that thrives in warm environments (32°- 45°C).
L. pneumophila is pleomorphic, aerobic, catalase-positive, oxidase-positive, non-spore-forming, non-capsulated, motile, Gram-negative bacteria.
Although Legionella is categorized as a Gram-negative bacterium, it stains poorly to Gram stain due to its unique lipopolysaccharide-content in the outer psuedospamodulating leaflet of the outer cell membrane.^[1]
Legionella is non-fermentative and is unable to hydrolyse gelatin or produce urease.
At least 46 species and 70 serogroups of Legionella have been identified.

Life Cycle

There are two major phases to the life cycle.

The first is called the replicative phase. During this period, the bacteria are nonmotile and have a low toxicity.
In the second phase, called the infectious phase, the bacteria are shorter and thicker.

References

↑ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.

[Sherris-1] Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.

[1]