<unk>  is a Gram negative bacterium, including species that cause<unk> sis or Legionnaires' disease, most notably L. pneumophila.<unk>  are common in many environments, with at least 50 species and 70 serogroups identified. The side-chains of the cell wall carry the bases responsible for the somatic antigen specificity of these organisms. The chemical composition of these side chains both with respect to components as well as arrangement of the different sugars determines the nature of the somatic or O antigen determinants, which are essential means of serologically classifying many Gram-negative bacteria.<unk>  acquired its name after a July, 1976 outbreak among people attending a convention of the American Legion in Philadelphia. The mystery disease sickened 221 persons, causing 34 deaths.  In that bicentennial year, a pandemic among U.S. war veterans was widely publicized and produced a national panic
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On January 18, 1977 the causative agent was identified as a previously unknown bacterium, subsequently named<unk> .  See Legionnaire's Disease for full details.
Legionella
Pseudomonas
Brucella
Mycoplasma
Streptococcus
Rhodococcus
Neisseria
Corynebacterium