Summary Neisseriae genus

Neisseriaceae
The genus Neisseria belongs to the
family Neisseriaceae.

, Important properties (Neisseria)
Commensal of mucosa
Approximately 11 species colonize humans, only
two are pathogens
 N. gonorrhoeae(also called the gonococcus)
N. meningitidis(also called the meningococcus)
Gram-negative diplococci with their adjacent sides
flattened- (kidney shaped or coffee beans)
Are aerobic
strongly oxidase-positive (contain the enzyme
cytochrome)
Are catalase positive
 susceptible to drying

, Cont
Non-motile, non sporing
Require 5 – 10% CO2 for growth
Fastidious-Require enriched media e.g. Thayer
– Martin Media, CBA-Chocolate Blood Agar
Growth is inhibited by toxic metals and fatty
acids and are therefore cultured on chocolate
Blood agar.
Meningococci are encapsulated
Meningococci ferments glucose and maltose while
gonococci ferments glucose only.

, Cont
Found inside polymorphonuclear pus cells of
the inflammatory exudates (intracellular).
Neisseriae contain endotoxin in their outer
membrane.
N. menengitidis is a lipopolysaccharide(LPS)
N. gonorrhoeae is a lipooligosaccharide (LOS)
Both organisms may bear fimbrae.
Both pathogens produce IgA proteases which
promote virulence