Infectious Diseases Flashcards
What is meningitis?
Inflammation of the meninges that line the brain and spinal cord, usually due to a bacterial or viral infection.
What is the most common causative organism in bacterial meningitis in children and adults?
Neisseria meningitidis (gram negative diplococcus; circular, occurs in pairs; meningococcus)
Streptococcus pneumoniae (pneumococcus)
What is meningococcus septicaemia and what is it the cause of?
Meningococcus bacterial infection in the blood stream.
Causes the non-blanching rash which indicates that the infection has caused DIC and subcutaneous haemorrhages.
What is meningococcal meningitis?
When the bacteria is infecting the meninges and the CSF around the brain and spinal cord.
What is the most common cause of bacterial meningitis in neonates?
Group B streptococcus (GBS)
Usually contracted during birth from GBS bacteria that live harmlessly in the mother’s vagina.
What causes the non-blanching rash?
Meningococcal septicaemia (other causes of bacterial meningitis does not cause the rash)
How do children typically present with meningitis?
- fever
- neck stiffness
- photophobia
- vomiting
- headache
- altered consciousness
- seizures
- non-blanching rash (meningococcal septicaemia)
How do babies and neonates present with meningitis?
Very non-specific signs and symptoms
- hypotonia
- poor feeding
- lethargy
- hypothermia
- bulging fontanelle
According to NICE, when should a lumbar puncture be included as part of investigations for children?
- <1 month presenting with fever
- 1 to 3 months with fever and unwell
- <1 year with unexplained fever and other features of serious illness
What 2 special tests can be performed to look for meningeal irritation?
1) Kernig’s test
2) Brudzinski’s test
What is Kernig’s test?
- lie patient on their back, flex one hip and knee to 90 degrees
- slowly straighten knee whilst keeping hip flexed at 90 degrees
- this creates a slight stretch in the meninges
- in meningitis it will produce spinal pain or resistance to movement
What is Brudzinski’s test?
- lie patient flat on back
- use hands to gently life their head and neck off the bed and flex their chin to their chest
- positive test for meningitis if causes patient to involuntarily flex their hips and knees
What should children in primary care with suspected meningitis and non-blanching rash be given prior to transfer to hospital?
Urgent stat injection (IM/IV) of benzylpenicillin
Do not delay transfer to hospital however.
What investigations would ideally be done if suspect meningitis?
- blood culture
- lumber puncture (CSF)
Prior to starting abx but do not delay if patient is acutely unwell.
What investigation should be done if meningococcal disease is suspected?
- blood tests for meningococcal PCR which tests directly for meningococcal DNA (quicker result than blood culture and will still be positive after abx)
What abx should be given to children to treat bacterial meningitis?
<3 months:
- cefotaxime PLUS amoxicillin
> 3 months:
- ceftriaxone
What does amoxicillin cover in those <3 months?
Listeria contracted during pregnancy.
When should vancomycin be added to abx in treating meningitis?
If there is a risk of penicillin resistant pneumococcal infection e.g. recent foreign travel, prolonged abx exposure
What are steroids used for in bacterial meningitis?
To reduce the frequency and severity of hearing loss and neurological damage.
What steroid is given to children and at what age for meningits?
Dexamethasone 4 times daily for 4 days
Children >3 months if LP suggestive of bacterial meningitis
What must be done in confirmed cases of bacterial meningitis and meningococcal infection?
They are notifiable diseases so public health need to be informed of all cases.
When is the risk highest for people that have had close prolonged contact with a patient with meningococcal infections?
Within the 7 days prior to onset of illness.
Risk decreases 7 days after exposure.
If no symptoms have developed 7 days after exposure they are unlikely to develop the illness.
What is the usual management for post-exposure prophylaxis for meningitis?
A single dose of ciprofloxacin given ASAP and ideally within 24 hours of initial diagnosis.
What are the most common causes of viral meningitis?
- herpes simplex virus (HSV)
- enterovirus
- varicella zoster virus (VZV)
What investigation should be done if suspect viral meningitis?
Sample of CSF from LP sent for viral PCR testing
What samples are sent from a lumbar puncture?
- bacterial culture
- viral PCR
- cell count
- protein
- glucose
What should be sent at the same time to compare the CSF sample from the lumbar puncture?
Blood glucose.
How does a bacterial cause present in CSF sample?
- cloudy appearance
- high protein (bacteria release proteins)
- low glucose (bacteria uses up glucose)
- high WCC (neutrophils - immune system releases them in response to bacteria)
- culture = bacteria
How does a viral cause present in CSF sample?
- clear appearance
- mildly raised/normal protein (viruses release small amount of protein)
- normal glucose (viruses don’t use glucose)
- high WCC (lymphocytes - immune system releases them in response to viruses)
- culture = negative
What are complications of meningitis?
- hearing loss (KEY complication)
- seizures & epilepsy
- cognitive impairment and learning disability
- memory loss
- cerebral palsy (focal neurological deficits e.g. limb weakness, spasticity)
