CNS Infection: Meningitis

Question 1

Epidemiology

Answer 1

Immunocompromised =
- Extremes of age (children and elderly)
- Infection (HIV)
- Medication (chemotherapy)
Non-immunised = H.influenza , pneumococcal and meningococcal meningitis
Crowded environment = student living in halls of residence are a commonly affected demographic

Question 2

Risk factors

Answer 2

Winter
Organ dysfunction
- Absent or non-functioning spleen
Smoking

Question 3

Most common bacterial causes of meningitis

Answer 3

Neisseria meningitis (meningococcus) = capsular group B accounts for majority of cases
Streptococcus pneumoniae (pneumococcus) = most common cause of bacterial meningitis in adults

Question 4

Most common viral causes of meningitis

Answer 4

Enteroviruses
e.g. coxsackievirus

Question 5

Causes of meningitis in neonates (0-3 months)

Answer 5

Group B Alpha haemolytic strep (s.agalactiae) = COLONISES MATERNAL VAG
Listeria monocytogenes
E.coli
S.pneumoniae

Question 6

Causes of meningitis in infants (3m-6y)

Answer 6

S. pneumo
N. meningitidis
H. influenzae (less common due to vaccination)

Question 7

Causes of meningitis in adults (6-60 years)

Answer 7

S. pneumo
N. meningitidis

Question 8

Causes of meningitis in elderly (60 + years)

Answer 8

S. pneumo
N. meningitidis
Listeria monocytogenes

Question 9

Which bacteria is most likely to affect pregnant women

Answer 9

Listeria Monocytogenes

Question 10

N. meningitidis

Answer 10

Gram negative diplococcus
Vaccines available - men B + C, men ACWY
10% mortality
NON-BLANCHING PURPURIC RASH (meningococcal septicaemia -> DIC -> v.easy bleeds)

Question 11

S. pneumoniae

Answer 11

gram positive streptococci
PCV vaccine
25% mortality

Question 12

Group B strep

Answer 12

Gram positive streptococci
MC of neonatal meningitis as COLONISES MATERNAL VAGINA

Question 13

Listeria monocytogenes

Answer 13

Gram positive bacillus
Affects extremes of age and maternal pregnant women (found in cheese)

Question 14

Pathophysiology

Answer 14

Meningitis describes inflammation of the leptomeninges (the arachnoid and pia mater) and usually occurs due to a bacterial, viral, or fungal infection. It can also be caused by trauma, cancer, or drugs.
Meningococcal septicaemia = when the meningococcal bacterial infection is in the bloodstream = cause of the classic ‘non-blanching rash’ = sign of DIC + Subcutaneous haemorrhages

Question 15

Signs

Answer 15

Kernig’s sign: Severe stiffness of the hamstrings causes an inability to straighten the leg when the hip is flexed to 90 degrees
Brudzinski sign: severe neck stiffness causes the hip and knees to flex when the neck is flexed
Petechial or purpuric non-blanching rash: associated with meningococcal disease (N. meningitidis)
Pyrexia
Reduced GCS

Question 16

Symptoms

Answer 16

Meningism
- headache
- photophobia
- neck stiffness
Fever
Nausea and Vomiting
Seizures
Altered consciousness
Lethargy

Question 17

Neonates presentation (HHELP)

Answer 17

Hypotonia
Hypothermia
bulging fontanElle
Lethargy
Poor feeding

Question 18

Papilloedema

Answer 18

1) venous enlargement
2) optic disc blurring
3) haemorrhages near optic disc
4) loss of venous pulsation
- Bilateral if there is increased intracranial pressure

Question 19

Diagnosis

Answer 19

Lumbar puncture + CSF analysis
- sample taken from L3/4 and analysed
Bloods
- FBC = leucocytosis
- CRP
- blood glucose = required in all patients and for comparison with CSF glucose

Question 20

Bacterial CSF analysis

Answer 20

Opening pressure = high
Appearance = cloudy yellow
WCC = increased neutrophilia
Protein = High >1g/L
Glucose (vs serum level) = Low < 50% serum level

Question 21

Viral CSF analysis

Answer 21

Opening pressure = normal
Appearance = clear, normal
WCC = increased lyphocytes
Protein = <1g/L
Glucose (vs serum level) = normal < 60% serum level

Question 22

Fungal CSF analysis

Answer 22

Opening pressure = high
Appearance = cloudy + fibrinous
WCC = increased lymphocytosis
Protein = High >1g/L
Glucose (vs serum level) = Low < 50% serum level

Question 23

Management

Answer 23

Dexamethasone: ideally should be administered before or with the first dose of antibiotics once in hospital
Ceftriaxone/ Cefotaxime (3rd gen cephalosporins)
- amoxicillin - covers listeria

Question 24

Bacteria specific treatment

Answer 24

Empirical antibiotics: aged < 3 months = IV cefotaxime and amoxicillin
Empirical antibiotics: aged 3 months - 50 years = IV cefotaxime
Empirical antibiotics: aged > 50 years = IV cefotaxime and amoxicillin
Meningococcal meningitis = IV benzylpenicillin (or cefotaxime)
Pneumococcal meningitis = IV cefotaxime
Haemophilus influenzae meningitis = IV cefotaxime
Listeria monocytogenes meningitis = IV amoxicillin and gentamicin

Question 25

Viral meningitis

Answer 25

Aciclovir

Question 26

Complications

Answer 26

DIC
WATERHOUSE FRIEDRICHSEN SYNDROME