Legionella

Pathogenic genus of Gram-negative bacteria

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. Most Legionella species are intracellular pathogens whose primary hosts are amoebae, however many Legionella are accidental pathogens of humans. Legionella bacteria are known to cause legionellosis (all illnesses caused by Legionella) including a pneumonia-type illness called Legionnaires' disease and a mild flu-like illness called Pontiac fever.

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