The Neisseriaceae are a family of Proteobacteria, given their own order. While many organisms in the family are mammalian commensals or part of the normal flora, the genus Neisseria includes 2 important human pathogens, specifically those responsible for gonorrhea and many cases of meningitis. As a group, Neisseriaceae are strictly aerobic, Gram-negative, occur mainly in pairs (diplococci), and typically do not have flagella.