Neisseria meningitidis

  • neisseria = Gram-negative aerobic diplococcus 
  • An encapsulated organism, resistant to opsonization
    • its capsule protects it against complement-mediated bacteriolysis and phagocytosis by neutrophils, Kupffer cells, and spleen macrophages.
  • Rarely resistant (just watch us)

epidemiology

  • Incubation 3-5 days
  • Antibody-mediated immunity is the most potent defence
  • The peak incidence of the disease occurs in the first year of life
    (following the loss of maternal antibody)
  • Progressively less common throughout childhood
  • Extremely rare in immunocompetent adults

virulence factors

  • LPS endotoxin as part of outer membrane
  • polysaccharide capsule - evade host phagocytosis
  • fimbriae mediate attachment to nasal epithelial cells
  • produces IgA protease cleaving IgA antibodies

clinical presentation/complications

management

  • ceftriaxone or benpen
  • steroids not indicated unless meningitis present

public health

  • close contacts - rifampicin or ciprofloxacin
  • highest risk: household contacts, highest in the 1st 7 days
  • chemoprophylaxis aims to eliminate established carriage