Meningitis: Emergency Management and CSF Interpretation

Meningitis is inflammation of the meninges, the membranes that cover the brain and spinal cord. Bacterial meningitis is a medical emergency that can kill or cause permanent disability within hours. Antibiotics must never be delayed while waiting for tests.

Causes

• Bacterial:
  • Streptococcus pneumoniae and Neisseria meningitidis in adults and children
  • Haemophilus influenzae type b where vaccine coverage is low
  • Listeria monocytogenes in neonates, older adults, pregnancy and immunosuppression
  • Group B streptococcus and E. coli in neonates
• Viral: enteroviruses and herpes viruses. Usually milder.
• Tuberculous: subacute onset; important in high-TB-burden countries.
• Fungal: Cryptococcus, especially in advanced HIV.

Clinical features

Classic features:

• fever
• headache
• neck stiffness
• altered mental state

Not all are present in every patient. Other features:

• photophobia
• vomiting
• seizures
• focal neurological signs
• Kernig's and Brudzinski's signs

A non-blanching petechial or purpuric rash suggests meningococcal disease. Infants may show only fever, irritability, poor feeding, lethargy and a bulging fontanelle.

Immediate management

1. ABCDE assessment and resuscitation. Watch for septic shock.
2. Blood cultures, then immediate empirical IV antibiotics. For example, ceftriaxone or cefotaxime, plus amoxicillin or ampicillin if Listeria is possible, following local guidelines. Add aciclovir if encephalitis is suspected.
3. If meningococcal disease is suspected outside hospital, give IM or IV benzylpenicillin (or a cephalosporin) before transfer, according to local guidance.
4. Dexamethasone with or just before the first antibiotic dose in suspected bacterial (especially pneumococcal) meningitis, according to guidelines.
5. Lumbar puncture when safe. Do a CT head first if there are:
   • signs of raised intracranial pressure
   • focal neurological signs
   • a reduced or falling level of consciousness
   • new seizures
   • immunosuppression
   Antibiotics are still given first.

CSF findings

• Bacterial:
  • appearance: cloudy
  • cells: high neutrophils
  • protein: high
  • glucose: low (CSF:blood ratio below about 0.5)
• Viral:
  • appearance: clear
  • cells: lymphocytes
  • protein: normal or mildly raised
  • glucose: normal
• Tuberculous:
  • appearance: clear or with a fibrin web
  • cells: lymphocytes
  • protein: very high
  • glucose: low
• Fungal:
  • appearance: clear
  • cells: lymphocytes
  • protein: high
  • glucose: low

Also send CSF for:

• Gram stain
• culture
• PCR (bacterial and viral)
• tests for TB and Cryptococcus where indicated

Complications

• Hearing loss (arrange a hearing test after bacterial meningitis).
• Seizures.
• Hydrocephalus.
• Cerebral oedema.
• Cognitive impairment.
• Limb loss from meningococcal sepsis.
• Death.

Public health

• Meningococcal disease is notifiable.
• Close contacts receive antibiotic prophylaxis, for example ciprofloxacin or rifampicin.
• Vaccines against Hib, pneumococcus and meningococcus have greatly reduced cases.

Exam pearls

• Never delay antibiotics for a CT scan or lumbar puncture.
• A non-blanching rash with fever is meningococcal sepsis until proven otherwise.
• Add cover for Listeria in older people, pregnant women and the immunocompromised.

See also Sepsis, Tuberculosis and our Exam Night Notes 1.0: Neurology.

Test yourself

5 exam-style single-best-answer questions. Choose your answer, then tap “Show answer”.

1. CSF: turbid, high neutrophils, high protein, low glucose. Likely cause?

   1. Normal
   2. Viral
   3. Bacterial
   4. Fungal
   5. Tuberculous
   Show answer

   Answer: C. Bacterial
   Neutrophilic CSF with low glucose is typical of bacterial meningitis.

2. Which situation requires a CT head before lumbar puncture?

   1. Fever alone
   2. Photophobia alone
   3. Focal neurological signs or reduced consciousness
   4. Neck stiffness alone
   5. Headache alone
   Show answer

   Answer: C. Focal neurological signs or reduced consciousness
   Signs of raised ICP, focal signs, seizures, reduced consciousness or immunosuppression need CT first — but antibiotics are given first.

3. Which organism needs extra cover in older adults and pregnancy?

   1. Neisseria meningitidis
   2. Cryptococcus
   3. Haemophilus influenzae
   4. Listeria monocytogenes
   5. Enterovirus
   Show answer

   Answer: D. Listeria monocytogenes
   Add amoxicillin/ampicillin to cover Listeria in neonates, older people, pregnancy and immunosuppression.

4. Fever with a non-blanching purpuric rash suggests:

   1. Meningococcal sepsis
   2. ITP only
   3. Allergy
   4. Measles
   5. Viral exanthem
   Show answer

   Answer: A. Meningococcal sepsis
   Treat as meningococcal disease until proven otherwise.

5. Which complication should be checked after bacterial meningitis?

   1. Myopia
   2. Diabetes
   3. Hair loss
   4. Hearing loss
   5. Dental caries
   Show answer

   Answer: D. Hearing loss
   Sensorineural hearing loss is common; arrange a hearing test.

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Disclaimer

For education and exam preparation only. This is not medical advice and must not be used to diagnose or treat patients. Always follow current clinical guidelines and the advice of qualified senior colleagues.