Rabbit anti-Legionella pneumophilia Legionella Spp. polyclonal antibody for IHC, ELISA, FC, WB, IP. Legionella is a pathogenic Gram negative bacterium, including species that cause legionellosis (Legionnaires disease), most notably L. pneumophila. It may be readily visualized with a silver stain. Legionella is common in many environments, with at least60species 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.