legionella steelei legionella steelei legionella steelei is a gram-negative bacterium from the genus legionella which was isolated from specimens of the respiratory tract of patients with bronchitis in california and south australia. legionella steelei scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: legionellales family: legionellaceae genus: legionella species: l. steelei binomial name legionella steeleiedelstein et al. 2012 type strain atcc baa-2169, imvs 3113, imvs 3376