legionella geestiana legionella geestiana legionella geestiana is a gram-negative bacterium from the genus legionella. legionella geestiana scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: legionellales family: legionellaceae genus: legionella species: l. geestiana binomial name legionella geestianadennis et al. 1993 type strain atcc 49504, ccug 44893, cip 105569, dennis 1308, nctc 12373