1. In the patient with a non-specific febrile illness, look for meningitis, especially in patients at higher risk (e.g., immuno-compromised individuals, alcoholism, recent neurosurgery, head injury, recent abdominal surgery, neonates, aboriginal groups, students living in residence).
  2. When meningitis is suspected ensure a timely lumbar puncture.
  3. In the differentiation between viral and bacterial meningitis, adjust the interpretation of the data in light of recent antibiotic use.
  4. For suspected bacterial meningitis, initiate urgent empiric IV antibiotic therapy (i.e., even before investigations are complete).
  5. Contact public health to ensure appropriate prophylaxis for family, friends and other contacts of each person with meningitis.

General Overview

  • Etiology
    • Neonates (0-1mo) = LEG
      • Listeria monocytogenes
      • E Coli
      • Group B Strep (S agalactiae)
    • >1mo = SHiN
      • S Pneumonia
      • H influenza
      • N Meningitidis
      • If >50yo or immunocompromised, alcoholism
        • Listeria monocytogenes
    • Viral (aseptic)
      • Enterovirus
      • HSV
      • Lyme (Borrelia burgdorferi)


  • Risk factors
    • Age ≥65 years old, Neonates, Aboriginal groups, Students living in residence
    • Immunocompromised (16%), Alcoholism, IVDU
    • Infection
      • Recent otitis or sinusitis (25%), mastoiditis
      • Pneumonia (12%)
      • Endocarditis
    • Recent neurosurgery, Head trauma
    • Recent travel to area with endemic meningococcal disease (eg. sub-Saharan Africa)
  • Symptoms
    • Headache, fever, neck stiffness, and altered mental status (two of the following 95% sensitive)
      • 99% have at least one classic feature - thus absence of all four findings above essentially excludes bacterial meningitis
    • Nausea, vomiting
    • Photophobia
    • Seizure and focal neurologic deficits (especially in Listeria)
      • Rhombencephalitis (manifested as ataxia, cranial nerve palsies, and/or nystagmus)
    • Petechiae and palpable purpura (especially in N meningitidis)
    • Arthritis (especially in N meningitidis)

Physical Exam

  • Meningeal signs
    • Neck stiffness (31% sensitive)
    • Kernig's (9%)
      • Inability or reluctance to allow full extension of the knee when the hip is flexed 90 degrees
    • Brudzinski (11%)
      • Spontaneous flexion of the hips during attempted passive flexion of the neck
    • Jolt accentuation (97%)
      • Accentuation of headache by horizontal rotation of the head at a frequency of two to three times per second
    • Bulging fontanelle in children
  • Neurological
    • Papilledema, seizure, focal deficit
  • Petechiae and palpable purpura


  • Droplet precautions (until 24h after antibiotics)
  • Empiric Antibiotics (do not delay beyond 1h if possible)
    • 0-1mo: Ampicillin + Cefotaxime (or Ampicillin + aminoglycoside)
    • >1mo: Vancomycin + 3rd gen cephalosporin (Ceftriaxone 2g IV q12h or Cefotaxime 2g IV q4-6h)
      • Vancomycin 15-20mg/kg IV q8-12h (pre 4th dose trough levels 15-20mcg/mL) + Ceftriaxone 2g IV q12h
    • >50y: Add Ampicillin 2g IV q4h to cover Listeria monocytogenes
  • Dexamethasone 10mg q6h x 4 days if suspect S. pneumoniae (reduce mortality), or H influenzae (reduce hearing loss)
    • Best to administer prior or with initial antibiotic therapy
    • Consider Rifampin instead of vancomycin if bacteria not sensitive to ceftriaxone, as vancomycin may not enter CSF as well after steroids decreased inflammation
  • Consider Acyclovir if suspect HSV encephalitis (changes in personality, behaviour, cognition, AMS)
  • Consider covering for P. aeruginosa in immunocompromised with Cefepime or Meropenem 2g IV q8h
  • Consider covering for tuberculous and cryptococcal meningitis in immunocompromised


  • Do not delay treatment for investigations, increase in mortality of 13% per hour of delay

CT Head (r/o midline shift, hydrocephalus - enlarged ventricles, posterior fossa mass)

  • Do CT head prior to LP if any of the following (prevent brain herniation):
    • Age >60yo
    • Immuncompromised (HIV, immunosuppressive therapy)
    • CNS disease (mass lesion, stroke, or focal infection)
    • Seizure (new onset within 1 week)
    • Focal neurological deficit (excluding cranial nerve palsies)
    • Papilledema
    • Altered mental status (GCS<10)
      • Unable to answer two consecutive questions or follow two consecutive commands

Lumbar Puncture

  • Consider delaying LP if unstable, signs of herniation, coagulopathy, overlying infection,
  • If no concerns or negative CT head, proceed to lumbar puncture
    • CSF opening pressure (if done in left lateral decubitus)
    • CSF leukocyte count, protein, glucose
    • CSF culture (70-85% positive, antibiotics decreases yield by 10-20%)
    • CSF Gram stain (60-90% positive with excellent specificity, yield decreases 20% if antibiotics)
      • Gram-positive rods and coccobacilli (think L monocytogenes) add Ampicillin
      • Gram-positive diplococci = pneumoccocal
      • Gram-negative diplococci = meningococcal
      • Small pleomorphic gram-negative coccobacilli = H influenzae
    • CSF PCR (Meningococcal, Pneumococcal, Enteroviral, HSV, VZV)
    • Consider CSF lactate and CRP to differentiate bacterial from aseptic (limited value if received antibiotic or CNS disease)

CSF Findings

  • Neonates or immunocompromised may have normal CSF findings in bacterial meningitis
  • L monocytogenes may present with CSF profile similar to viral, WBC >100 and normal glucose


  • CBC
  • Electrolytes (Mild hyponatremia)
  • LFTs
  • Coags
  • VBG (AGMA)
  • Blood cultures x2 (60% positive) before first dose of antibiotics if possible
  • Consider
    • If sexual history or substance use: serum RPR, CSF VDRL, serum HIV Ab and HIV PCR
    • In children (to guide diagnosis): Serum CRP and pro-calcitonin
    • Throat swab for meningococcal culture


  • Droplet precautions
  • Chemoprophylaxis to close contacts and direct exposure to respiratory secretions
    • Contact public health for post-exposure prophylaxis for close contacts (7d prior to symptom onset until 24h treatment)
      • N meningititidis (>8h close contact or oral secretions)
        • Ciprofloxacin 500mg PO x1, Rifampin 600mg PO q12h x2d, Ceftriaxone 250mg IM x1
      • H influenzae (household with unvaccinated)
        • Rifampin
  • Vaccination (H influenzae B, Pneumococcal, N Meningitidis)
  • Pregnancy
    • Pen G to cover GBS as indicated
    • Avoid soft cheeses with unpasteurized milk, raw sprouts, melons, cold cuts, smoked seafood (Listeria monocytogenes)