Bacterial Meningitis Flashcards
What is meningitis?
Inflammation of the meninges covering the brain
What usually precedes a bacterial infection of the meninges?
Bacteraemia
What is responsible for the damage caused by meningeal infection?
Host response to the organism
What changes influence the damage caused by the immune system?
- Release of inflammatory mediators
- Activated leukocytes
- Endothelial damage
What can occur as a result of immune response in meningitis?
- Cerebral oedema
- Raised ICP
- Decreased cerebral blood flow
What effect can inflammatory response have below the meninges?
Vasculopathy leading to cerebral cortical infarction
How may meningitis cause hydrocephalus?
Fibrin deposits may block CSF reabsorption
What does the causative organism vary according to?
Age of the child
What are the most common causative organisms in neonates - 3 months?
- Group B strep
- E. coli
- Listeria monocytogenes
What are the most common causative organisms in 1 month - 6 years?
- Neisseria meningitides
- Strep pneumoniae
- Haemophilus influenzae
What are the most common causative organisms in >6 year olds?
- Neisseria meningitides
- Strep pneumoniae
What has affected the commonness of causative organisms over time?
Introduction of vaccines
How may meningitis present in general?
- Non-specifically
- With specific symptoms
What is the result of meningitis sometimes presenting with non-specific symptoms?
It can be hard to distinguish from other conditions
What are some non-specific symptoms of meningitis?
- Fever
- N&V
- Lethargy
- Irritability
- Refusing food
- Headache
- Muscle aches/joint pains
What are some more specific symptoms of meningitis?
- Non-blanching rash
- Stiff neck
- Altered mental state
- Shock
- Photophobia
- Bulging fontanelle
- Focal neurological deficits
- Seizures
How may focal neurological deficits present?
- Cranial nerve involvement
- Abnormal pupils
What physical examination tests may be useful when looking for meningitis?
Kernig’s and Brudzinski tests
What is a positive Kernig’s test?
Where the patient lies supine and the knee is unable to fully extend when the hip is flexed to 90 degrees
What is a positive Brudzinski test?
When the patient is lying supine and lifting the patients head causes flexion of the knees and hips
What are the risk factors for bacterial meningitis?
- Young children
- Immune deficiency
- Contact with someone with meningitis
What tests should be performed on any child with an unexplained fever and rash?
- FBC
- CRP
- Coag screen
- Blood culture
- Whole blood PCR for N. meningitides
- Blood glucose
- Blood gas
What other investigation should be performed if suspecting meningitis unless contraindicated?
LP
What are the contraindications for lumbar puncture?
- Signs of raised ICP
- Extensive purpura
- Convulsions
- Coagulation abnormalities
How should the CSF be investigated following LP?
- WBC count
- Total protein and glucose concentrations
- Gram stain and culture
What are some differentials for bacterial meningitis?
- Encephalitis
- Meningococcal septicaemia
- Sepsis
What is the main curative treatment for bacterial meningitis?
Antibiotics
What antibiotics are given to infants under 3 months?
IV cefotaxime with amoxicillin OR ampicillin
What antibiotics are given to children over 3 months?
IV ceftriaxone
What should be given as an additional antibiotic if the patient has recently travelled outside the UK or has had prolonged antibiotic exposure in the last 3 months?
Vancomycin
What drug should be given if indicated by LP result?
Dexamethasone
How should dexamethasone be administered if indicated?
0.15mg/kg to max dose of 10mg QDS for 4 days if over 3 months
What LP results indicate need for dexamethasone?
- Frankly purulent CSF
- CSF WBC > 1000/uL
- Raised CSF WBC with protein > 1g/L
- Bacteria on gram stain
What supportive management should be given?
- Respiratory support
- Fluids
If the patient is self-ventilating what respiratory support should be given?
15L oxygen via non-rebreathe mask
If there is loss of airway patency what management step is necessary?
Intubation
What complications should be monitored for when the child is intubated?
- Aspiration
- Pulmonary oedema
- Worsening shock
How should the need for fluids be assessed in a patient with bacterial meningitis?
Look for signs of dehydration, shock and raised ICP
If fluids are needed how should the deficit be corrected?
Enteral or IV fluids
What type of fluids should be given in IV replacement?
Isotonic e.g. saline
In neonates what maintenance fluids should be used?
Glucose 10% with added sodium chloride
When should fluids be restricted?
Only if there is raised ICP or raised ADH
What signs of deterioration should be monitored?
- RR
- Pulse
- BP
- SpO2
- GCS
What public health measures must be taken if a patient has bacterial meningitis?
- Notify PHE
- Potential need for prophylactic antibiotics for close relatives
What antibiotic can be given as prophylaxis for bacterial meningitis?
Rifampicin
What are the potential complications of bacterial meningitis?
- Death
- Deafness
- Epilepsy
- Hydrocephalus
- Cognitive deficits
