Neisseriaceae

Neisseriaceae is a family of Gram-negative, nonmotile bacteria in the order Neisseriales, class Betaproteobacteria. Members are commonly found on mucous membranes of vertebrates and range from harmless commensals to important human pathogens.

The family comprises several genera, most notably Neisseria, Eikenella, and Kingella. Neisseria includes species such as Neisseria meningitidis and Neisseria gonorrhoeae; Eikenella corrodens is associated with the human oral cavity and bite-related infections; Kingella species are found in the oropharynx and can cause disease in some circumstances.

Morphology and physiology: Neisseria are Gram-negative diplococci that are oxidase-positive and typically aerobic or facultatively anaerobic. Many species are encapsulated, and virulence in N. meningitidis is linked to its capsule. Distinguishing Neisseria species in the laboratory can involve carbohydrate utilization patterns, with N. meningitidis able to ferment glucose and maltose, while N. gonorrhoeae ferments only glucose.

Pathogenicity and ecology: Members colonize human mucosa and other vertebrates, and effects range from benign carriage to invasive disease. N. meningitidis can cause meningitis and septicemia; N. gonorrhoeae causes gonorrhea and can disseminate. Eikenella corrodens and certain Kingella species are opportunistic pathogens associated with endocarditis, septic arthritis, and odontogenic infections.

Diagnosis and management: Isolation on enriched media such as chocolate agar, with selective media like Thayer-Martin used for Neisseria in clinical specimens. Gram staining may reveal Gram-negative diplococci. Treatment relies on antimicrobial susceptibility testing due to resistance concerns, particularly in N. gonorrhoeae. Vaccines exist for meningococcal disease targeting multiple capsule serogroups.