Infectious Disease: Meningitis Flashcards
Defintion
Inflammation of the meninges = lining of the brain and spinal cord. This is usually due to bacterial or viral infection
Bacteria
Neisseria meningitidis is a gram-negative diplococcus bacteria.
Meningococcal septicaemia
Refers to infection in the bloodstream
Causes a non-blanching rash suggestive of disseminated intravascular coagulopathy (DIC) and subcutaneous haemorrhages
Meningococcal meningitis
When the bacteria is infecting the meninges and the cerebrospinal fluid around the brain and spinal cord.
Aetiology
Neonates = Group B Strep (GBS)
- GBS is usually contracted during birth from GBS bacteria that live harmlessly in the mothers vagina
Children and adults = Neisseria meningitidis (meningococcus) + Strep pneumoniae (pneumococcus)
Viral =
- herpes simplex virus (HSV),
- enterovirus
- varicella zoster virus (VZV)
Signs and symptoms in children
Systemic symptoms :
- fever
- neck stiffness
- vomiting
- headache
- altered consciousness
- seizures
Specific signs;
- photo phobia
- neck stiffness
- non-blanching rash
Neonatal signs and symptoms
Very non specific signs:
- hypotonia
- poor feeding
- lethargy
- hypothermia
- bulging fontanelle
Special tests for meningeal irritation
Kernig’s test = lying patient on their back, flexing one hip to 90 degrees = slight stretch in the meninges
- Positive sign = spinal pain or resistance to movement
Brudzinski’s test = lying patient flat on their back + gently using hands to lift their head and neck off the bed + flex their chin to their chest.
- Positive test = patient involuntarily flex’s their hips and knees
NICE Lumbar puncture recommendations
Recommended as part of investigation for all children:
- Under 1 month presenting with fever
- 1 to 3 months with fever and are unwell
- Under 1 year with unexplained fever and other features of serious illness
Lumbar puncture process
Involves inserting a needle into the lower back to collect a sample of cerebrospinal fluid (CSF).
The spinal cord ends at the L1 – L2 vertebral level, so the needle is usually inserted into the L3 – L4 intervertebral space.
Samples are sent for bacterial culture, viral PCR, cell count, protein and glucose. A blood glucose sample should be sent at the same time so that it can be compared to the CSF sample. The samples need to be sent immediately.
CSF bacterial results
Appearance: Cloudy
Protein: High
Glucose: Low
White cell count: High (neutrophils)
Culture: Bacteria
CSF Viral results
Appearance: Clear
Protein: Mildly raised or normal
Glucose: Normal
White cell count: High (lymphocytes)
Culture: Negative
Diagnosis
FIRST LINE = CT of head and neck
GOLD STANDARD = Lumbar puncture
- A sample of the CSF from the lumbar puncture should be sent for viral PCR testing.
Treatment in community
Children seen in the primary care setting with suspected meningitis AND a non blanching rash should receive an urgent stat injection (IM or IV) of BENZYLPENICILLIN prior to transfer to hospital, as time is so important. The dose will depending on their age.
Where there is a true penicillin allergy, transfer should be the priority rather than finding alternative antibiotics.
Treatment in hospital
Ideally Blood culture + lumbar puncture performed prior to starting Abx. However in acutely unwell Px Abx should not be delayed
Typical antibiotics are:
- Under 3 months – cefotaxime + amoxicillin (the amoxicillin is to cover listeria contracted during pregnancy)
- Above 3 months – ceftriaxone
+ VANCOMYIN if risk of penicillin resistant pneumonoccal infection e.g. recent foreign travel or prolonged antibiotic exposure
+ STEROIDS to reduce frequency and severity of hearing loss and neurological damage = DEXAMETHASONE 4 times daily for 4 days to children over 3 months if LP shows bacterial picture.
Bacterial meningitis and meningococcal infection are notifiable disease so public health need to be informed of all cases
