What is Legionella in microbiology?

Legionella bacteria are aerobic, gram-negative, intracellular pathogens that are important causes of community-acquired and nosocomial pneumonia. Legionella infections can be acquired sporadically or during outbreaks. Legionella bacteria are typically transmitted via inhalation aerosols from contaminated water or soil.

In what way is Legionella spp fastidious?

These bacteria stain less intensely with safranin than do enteric bacilli. It is ironic that Legionella species are sometimes referred to as fastidious bacteria, because they may grow luxuriantly in tap water and can multiply in the usually hostile environment of phagocytic cells.

How does Legionella grow in macrophages?

Legionella attach to and are engulfed by alveolar macrophages where they are enclosed in ribosome lined phagosomes and avoid fusion with the lysosome. In the phagosome, replication of Legionella increases until the cell ruptures, liberating daughter Legionella to infect other cells.

Does Legionella have a capsule?

L. pneumophila is a Gram-negative, non-encapsulated, aerobic bacillus with a single, polar flagellum often characterized as being a coccobacillus. It is aerobic and unable to hydrolyse gelatin or produce urease.

Should Legionella be capitalized?

In American texts, the L is usually capitalized in the name Legionnaires’ disease. However, lower case is often used in Canada and Britain. Note the apostrophe at the end of Legionnaires’. The first recognized cases of Legionnaires’ disease occurred in Philadelphia.

How does Legionella get in water?

Potable water is the most important source of Legionella. Humans may inhale contaminated aerosols or aspirate small amounts of contaminated drinking water. No vaccine is available to prevent infection.

How is Legionella treated in water?

Chemical shock using an elevated level of a disinfectant, such as chlorine, for a limited duration can control Legionella in a potable water system.

How does Legionella bacteria enter the body?

People can get Legionnaires’ disease or Pontiac fever when they breathe in small droplets of water in the air that contain the bacteria. Less commonly, people can get sick by aspiration of drinking water containing Legionella. This happens when water accidently goes into the lungs while drinking.

Can Legionella be Gram stained?

Bacterial Pneumonia and Lung Abscess Legionella are obligatory aerobic, fastidious, gram-negative bacilli that stain poorly with Gram stain (see Chapter 17, Figure 17-4) and grow poorly on conventional media. L. micdadei and some other Legionella species may stain weakly acid-fast.

Is Legionella singular or plural?

Legionella is a bacterium (singular). It is a biological agent that can present a biohazard in the workplace. Bacteria (plural) are living single-celled micro-organisms that are very different from human cells in that they do not have a nucleus.