Bacterial Meningitis Flashcards by Elliot Jones

What is meningitis?

Inflammation of the meninges covering the brain

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What usually precedes a bacterial infection of the meninges?

Bacteraemia

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What is responsible for the damage caused by meningeal infection?

Host response to the organism

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What changes influence the damage caused by the immune system?

Release of inflammatory mediators
Activated leukocytes
Endothelial damage

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What can occur as a result of immune response in meningitis?

Cerebral oedema
Raised ICP
Decreased cerebral blood flow

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What effect can inflammatory response have below the meninges?

Vasculopathy leading to cerebral cortical infarction

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How may meningitis cause hydrocephalus?

Fibrin deposits may block CSF reabsorption

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What does the causative organism vary according to?

Age of the child

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What are the most common causative organisms in neonates - 3 months?

Group B strep
E. coli
Listeria monocytogenes

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What are the most common causative organisms in 1 month - 6 years?

Neisseria meningitides
Strep pneumoniae
Haemophilus influenzae

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What are the most common causative organisms in >6 year olds?

Neisseria meningitides

- Strep pneumoniae

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What has affected the commonness of causative organisms over time?

Introduction of vaccines

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How may meningitis present in general?

Non-specifically

- With specific symptoms

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What is the result of meningitis sometimes presenting with non-specific symptoms?

It can be hard to distinguish from other conditions

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What are some non-specific symptoms of meningitis?

Fever
N&V
Lethargy
Irritability
Refusing food
Headache
Muscle aches/joint pains

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What are some more specific symptoms of meningitis?

Non-blanching rash
Stiff neck
Altered mental state
Shock
Photophobia
Bulging fontanelle
Focal neurological deficits
Seizures

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How may focal neurological deficits present?

Cranial nerve involvement

- Abnormal pupils

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What physical examination tests may be useful when looking for meningitis?

Kernig’s and Brudzinski tests

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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?

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