Meningitis and Encephalitis Flashcards
Which organisms cause meningitis at what ages?
- Neonates – Group B streptococcus, E. Coli, Listeria monocytogenes
- 3 months – 6 year – Neisseria meningitidis, streptococcus pneumoniae and Haemophilus influenzae type B (HiB)
- 6 - 60 years – Neisseria Meningitidis and strep pneumoniae
- > 60 years - Strep pneumoniae, Neisseria Meningitidis and Listeria monocytogenes
- Immunocompromised – various but listeria common
What commonly causes chronic meningitis
Chronic Meningitis – chronic clinical course. M. tuberculosis – Granulomatous inflammation resulting in fibrosis of meninges and Nerve Entrapment specifically cranial nerves as it usually affects the base of the brain resulting in bulbar palsies.
How does meningitis present and what are the two eponymous signs?
Generally looking unwell, cold grey skin
Meningism triad - headache, photophobia and neck or back pain and stiffness
Also, nausea and vomiting, weakness and sensory loss.
Petechial, non-blanching rash, Raised ICP and shock
Low GCS and seizures
Prolonged CAP refill time
Kernig’s sign - inability to fully extend the knee when the hip is flexed.
Brudinski’s sign – passive flexion of the neck causes flexion of the thighs and knees
What are the two gross motor signs that can occur as meningitis progresses?
As Meningitis progresses and coning takes place then certain rigidity signs may appear:
Decorticate rigidity – limbs point to core – upper limb flexors > extensors and lower limb extensors > flexors
Decerebrate rigidity
How is meningitis investigated?
Lumbar puncture (contraindicated in Raised ICP due to conning)
CT scan
Bloods – FBC, CRP, U&Es, coagulation screen, blood gas, blood glucose, blood culture and whole blood PCR testing
How is meningitis managed?
If in non-hospital setting call ambulance and give IM benzylpenicillin if it will not delay transit
Stabilise and give IV antibiotics (if penicillin allergic then give chloramphenicol)
< 3 months or > 50 years old – IV cefotaxime and amoxicillin
3months – 50 years – IV cefriaxone
Give corticosteroids – dexamethasone (unless younger than 3 months) Give fluids (unless signs of raised ICP)
Public health notification and antibiotic prophylaxis of contacts if meningococcal meningitis using – ciprofloxacin
Once you know what organisms is causing the meningitis what antibiotics should be given?
Meningococcal – IV benzylpenicillin or cefotaxime for 7 days
Pneumococcal (14 days) or Haemophilus (10 days) – IV cefotaxime
Listeria – IV amoxicillin and gentamicin
If meningitis is caused by a meningococcal organism what other steps must be taken after treating the patient?
Meningococcal meningitis is notifiable, and households should be given prophylaxis e.g. with ciprofloxacin or rifampicin. Vaccination offered once serotypes are available. If pneumococcal no prophylaxis is needed.
How does a bacterial meningitis appear in CSF?
Cloudy (turbid) predominant cell types -= polymorphs Glucose < half of plasma High protein 10-5000/mm^3 white cells
How does a viral meningitis appear in CSF?
Clear Predominant cell type is mononuclear (lymphocytes) Glucose > Half of plasma Normal/raised protein 15-1000/mm^3 white cells
What is encephalitis?
Infection within the brain parenchyma.
Which organism causes 95% of viral encephalitis in adults?
Most commonly viral – HSV1 is the cause in 95% of adults.
Which lobes are most commonly affected by encephalitis?
Much more common to affect the temporal and inferior frontal lobes.
What non-viral organisms can cause encephalitis?
If non-viral usually TB, malarial, listeria, Lyme’s disease, legionella, leptospirosis, aspergillosis, cryptococcus, schistosomiasis and typhus.
What are the clinical features of encephalitis?
Suspect when there is an odd behaviour, reduced consciousness, focal neurology preceded by an infectious prodrome.
Fever, headache, psychiatric symptoms, seizures and vomiting
Focal features such as aphasia
