Polmoniti infettive - Medicina e Chirurgia - Università degli Studi di ...

Legionella pneumophila
Gram stain of Legionella
pneumophila from a colony,
counterstained with carbol-fuchsin.
Legionella are pleomorphic, aerobic
bacilli that stain faintly gram
negative. Longer filamentous forms
are seen in pure culture; in clinical
specimens, the organisms usually
appear as small coccobacilli.
Legionella species have a single
polar flagella and multiple pili and
share other ultrastructural features
of gram-negative bacilli. The family
Legionellaceae has more than 30
species. Twenty species have been
implicated in human disease, but
most cases of legionellosis are
caused by L. pneumophila groups 1,
4, and 6