CBL - Bacterial Meningitis

Question 1

Describe the classic triad of acute bacterial meningitis [3]

Answer 1

1. Fever (>38°C)
2. Nuchal rigidity
3. Change in mental status

Question 2

What is Brudzinski sign? [2]

Answer 2

1. refers to spontaneous flexion of the hips during attempted passive flexion of the neck.
2. it illustrates meningism; used to examine for neck stiffness/nuchal rigidity

Question 3

What is Kernig sign? [1]

Answer 3

the inability or reluctance to allow full extension of the knee when the hip is flexed 90 degrees

Question 4

List three important contraindications that may delay/defer performing a lumbar puncture [3]

Answer 4

1. Evidence of raised intracranial pressure
   
   • (mass effect on CT imaging or clinical signs of impending herniation)
2. Spinal epidural abscess
3. Thrombocytopenia

Question 5

If a lumbar puncture is delayed, what investigation must be done and why? [2]

Answer 5

• A CT scan should be performed to exclude a mass lesion or increased intracranial pressure
  
  • these abnormalities can albeit rarely lead to cerebral herniation during removal of CSF

Question 6

What are the 4 common causes of community-acquired bacterial meningitis in adults in developed countries? [4]

Answer 6

1. Streptococcus pneumoniae
2. Neisseria meningitidis
3. H. influenzae
4. Group B Streptococcus

Question 7

Listeria monocytogenes is an important bacterial cause of meningoencephalitis in which patient groups? [4]

Answer 7

1. Neonates
2. Pregnancy
3. Immunosuppressed
   
   • (malignancy, AIDS, organ transplant recipients or patients on corticosteroids)
4. Older patients

Question 8

Describe the cerebrospinal fluid (CSF) findings that would be suggestive of bacterial meningitis. How does this compare to aseptic (viral) meningitis? [6]

Answer 8

1. Bacterial Meningitis​​
   
   • High WBC count with a polymorph predominance
     
     • (% of neutrophils usually greater than 80%)
   • High protein >200 mg/dL (more in CSF than blood)
   • Low glucose <40 mg/dL (less in CSF than blood)
2. Aseptic (Viral) Meningitis
   
   • ​​High WBC count - lymphocytic
   • Slightly raised protein levels in CSF
   • Normal glucose levels in CSF

Question 9

When should you give corticosteroids to someone with meningitis and why? [2]

Answer 9

Death and neurological sequelae are significantly reduced by the administration of 10mg of dexamethasone 6hrly for 4 days in patients with pneumococcal meningitis either prior to or soon after administration of antibiotics