ABSTRACT
Microbiology Neisseria are fastidious Gram-negative diplococci which grow best in moist environments in the presence of 5–10% CO2. N. meningitidis and N. gonorrhoeae infect only humans and are the only pathogenic members of this genus. N. meningitidis expresses antigenically variable capsules that divide the species in to serogroups. Serogroups A, B, C and W135 cause the majority of infections.
