neisseria elongata neisseria elongata neisseria elongata is a gram negative bacterium and is different from the other cocci shaped members of the genus neisseria as it is rod shaped. unlike other neisseria it is catalase negative. n. elongata is the most ancestral of the human neisseria. neisseria elongata scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: neisseriales family: neisseriaceae genus: neisseria species: n. elongata binomial name neisseria elongatabovre and holten, 1970