II. Epidemiology
- Most common in young adults and children with bimodal peak
- Age under 2 years accounts for 50% of cases
- Also peaks in teens
-
Incidence
- Among top 2 causes of Bacterial Meningitis in U.S. (other is Streptococcal Pneumoniae Meningitis)
- Up to 2800 cases per year per year in the U.S.
- One case per 100,000 people
- Exposure risks
- Sporadic cases are most common
- Outbreaks in close quarters (e.g. Dormitory)
III. Pathophysiology
- Neisseria Meningitidis is normal oral flora in 10%
- Transmission
- Respiratory secretions passed via aerosol or contact
-
Polysaccharide capsule surrounds Neisseria Meningitidis
- Resistant to Phagocytosis in the absence of Opsonins (antibodies to capsule)
- Capsular Polysaccharides may become Antigens for Antibody response
- Serogroups are defined by the specific capsular Polysaccharides (13 have been defined)
- Meningitis is most commonly caused by serogroups A, B, C, as well as W-135, Y
-
Endotoxin
- Lipopolysaccharide Endotoxin is released from Meningococcus
- Triggers Hemorrhage and Sepsis
- IgA1 Protease
- Enzyme expressed by some pathologic Meningococcus
- Lyses IgA in half
- Pili
- Other pathogenic mechanisms
- Extracts iron from human Transferrin
IV. Risk Factors
- Living in dormitory or military barracks
- More common in white males
- Tobacco use or passive Tobacco exposure
- Recent Upper Respiratory Infection
V. Precautions: Presentations may be cryptic
- Nuchal Rigidity may be absent
- Severe Upper Respiratory Infection may be only initial presentation
- Petechiae and fever confers a 10-15% risk of Meningococcemia
- May present with concurrent other infections (e.g. Otitis Media, Conjunctivitis, Pneumonia)
VI. Symptoms
- Headache
- Myalgias or Arthralgias
- Vomiting
VII. Signs
- See Meningitis
- Fever
- Nuchal Rigidity may be absent
- Rash (70% of cases)
- Centripetal Rash (starts on distal extremities, wrists and ankles)
- May start with light pink maculopapular rash (may even blanch initially)
- Petechiae (non-blanching) are common
- Fulminant Purpura (20% of cases)
- Central gun-metal gray center
VIII. Labs
- See Bacterial Meningitis
- Neisseria Meningitidis appears as Gram Negative diplocci under microscopy
- Each coccus is Kidney bean shaped, facing and overlapping one another
IX. Management
- See Bacterial Meningitis Management
- If considered, obtain Lumbar Puncture and start empiric Antibiotics immediately
- Manage shock
- See Sepsis (covers fluid boluses and pressor use)
- Consider adding Corticosteroids to the Antibiotic regimen
- Meningococcus may be associated with adrenal infarction Hemorrhage
X. Complications
- Waterhouse-Friderichsen Syndrome
- Shock, Petechiae and adrenal infarction (bilateral adrenal Hemorrhage)
XI. Prevention
- See Meningococcal Vaccine
-
Vaccination does on confer 100% protection (misses some sub-groups)
- Known exposures to Meningococcal Meningitis need Antibiotic prophylaxis despite Immunization
XII. Prevention: Post-exposure Prophylaxis
- Indications
- Exposure from 7 days before onset of illness until 24 hours after Antibiotics initiated AND
- Significant exposure (treat if any concern)
- Household contacts (up to 800 fold increase in risk, up to 1 in 250 will be infected)
- Child care centers
- Oral secretion exposure (e.g. health care worker without adequate protection)
- Long-distance (>8 hours) travel next to source
- Prophylaxis options (pick one): Start as soon as possible (up to 14 days after exposure)
- Rifampin
- Age <1 month: 5 mg/kg orally every 12 hours for 2 days
- Age >1 month: 10 mg/kg (max: 600) orally every 12 hours for 2 days
- Adults: 600 mg orally every 12 hours for 2 days
- Ciprofloxacin (adults) 500 mg orally for one dose
- Ceftriaxone (Rocephin)
- Age <15 years: 125 mg IM for one dose
- Age >15 years: 250 mg IM for one dose
- Rifampin
- References
XIII. Prognosis
- Mortality: Approaches 14% despite treatment
- Serious residual morbidity approaches 19%
XIV. References
- Claudius in Majoewsky (2012) EM:Rap 12(11): 8
- Kimmel (2005) Am Fam Physician 72:2049-56 [PubMed]