neisseria sicca neisseria sicca neisseria sicca is a commensal organism belonging to the genus neisseria. it is gram-negative and oxidase-positive. there are multiple strains of this species, some of which are reported to have caused septicaemia in immunocompromised patients. these bacteria are the first among neisseria species to have been shown to have o-repeat structure in their liposaccharide. neisseria sicca scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: neisseriales family: neisseriaceae genus: neisseria species: n. sicca binomial name neisseria siccavon lingelsheim, 1908