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Updated: Mar 5 2021

Neisseria meningitidis


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  • Snapshot
    • An 18-year-old man presents to the emergency department for an intractable headache and generalized malaise. His symptoms began 3 days ago and have progressively worsened. Physical examination is significant for nuchal rigidity, diffuse petechia, and an inability to extend at the knee while the hips are flexed at 90°. A lumbar puncture is performed and cerebral spinal fluid studies demonstrate an elevated opening pressure, elevated protein, decreased glucose, and a leukocytosis. Gram stain of the cerebral spinal fluid demonstrates gram-negative diplococci.
  • Introduction
    • Classification
      • a gram-negative diplococcus
    • Epidemiology
      • risk factors
        • college students
        • military
        • infants and the elderly
        • no meningococcus vaccine
    • Transmission
      • respiratory and oral secretions
    • Microbiology
      • properties
        • metabolizes glucose
        • produces IgA proteases
        • contains lipooligosaccharides (has strong endotoxin activity)
        • aerobic or facultatively anaerobic
        • maltose fermenter
      • reservoir
        • nasopharynx
          • penetrates mucosal epithelium and enters circulation
            • pharynx → hematogenous spread (blood) → choroid plexus → meninges
      • molecular biology
        • virulence factors
          • polysaccharide capsule
            • an important virulence factor
              • provides resistance against phagocytosis
          • IgA protease
            • allows oropharynx colonization
          • endotoxin (lipooligosaccharide)
            • analogous to LPS from other gram-negative bacteria
            • causes hemorrhage and sepsis
            • responsible for petechial rash
              • small red dots of hemorrhage
          • pili
            • enables attachment to the nasopharynx
            • antigenic variation avoids the immune system attack
    • Pathogenesis
      • begins as asymptomatic colonization in the nasopharynx in healthy patients
        • in rare cases, the bacteria invade through the mucosa, resulting in bacteremia, which can allow seeding of the microbe to the meninges
        • an inflammatory response against the microbe (due to its endotoxin) ensues, leading to tissue injury
          • procoagulant pathways can also be activated, causing intravascular thrombosis (e.g., purpura and petechiae)
      • Patients deficient in components of the alternative and terminal complement (C5b-C9 - membrane attack complex) pathways have increased susceptibility to recurrent Neisseria bacteremia
    • Prevention
      • meningococcal vaccine
        • indication
          • all patients 11-18 years of age
          • ≤ 10 years of age and ≥ 19 years of age who are high risk for invasive meningococcal disease
    • Associated conditions
      • meningitis
      • meningococcemia
      • purpural fulminans
      • Waterhouse-Friderichsen syndrome
        • adrenal infarction leading to adrenal insufficiency
    • Prognosis
      • poor prognosis include shock, young and old age, coma, purpura fulminans, and disseminated intravascular coagulation
  • Presentation
    • Symptoms
      • headache
      • fever
      • neck stiffness
      • nausea and vomiting
      • myalgias
    • Physical
      • petechial rash
      • nuchal rigidity
      • Brudzinki sign
        • spontaneous flexion of the hips during passive neck flexion
      • Kernig sign
        • inability to extend the knees while the hips are flexed at 90°
  • Studies
    • Culture
      • perform a Gram stain of the cerebral spinal fluid or blood
        • gold standard for the diagnosis
  • Differential
    • Meningitis caused by other organisms
      • Streptococcus pneumoniae
      • Listeria monocytogenes
      • differentiating factors
        • different organisms are isolated with microbiologic testing
  • Treatment
    • Medical
      • empiric antibiotic therapy
        • indication
          • preferably given after cerebral spinal fluid cultures and blood cultures are obtained
            • given antibiotics first will impair diagnostic testing
        • regimen
          • third-generation cephalosporin
            • e.g., ceftriaxone or cefotaxime
      • antimicrobial chemoprophylaxis
        • indication
          • ideally given within 24 hours
            • household members
            • roommates or intimate contacts
            • direct exposure to oral or respiratory secretions (e.g., kissing and endotracheal intubation)
            • sitting next to the infectious person for ≥ 8 hours
            • patients who work in a childcare center
        • medication
          • rifampin
          • ciprofloxacin
          • ceftriaxone
  • Complications
    • Sepsis
    • Hypovolemic shock
    • Cerebral edema and hydrocephalus
    • Cognitive impairment
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