221 - Meningitis Flashcards

1
Q

What is meningitis?

A

Inflammatory disease of leptomeninges - the tissues surrounding the brain and spinal cord (arachnoid mater, CSF)

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2
Q

What is the mortality of meningitis?

A

100% if untreated (bacterial)
Bacterial - 10%
Viral - fewer complications

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3
Q

If there is a CNS infection of the parenchyma, what is it called?

A

Encephalitis

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4
Q

List some risk factors for meningitis

A
Under 5 or over 60
Diabetes
Renal/adrenal insufficiency
Cystic fibrosis, sickle cell
immunosuppression, HIV
Crowding
Splenectomy
Alcoholism
Dural defect
IV drug abuse
Malignancy
Bacterial endocarditis
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5
Q

What are the 2 patterns of the course meningitis runs

A

Progressive - ober a few days, deteriorate more steadily

Acute/Fulminant - Rapid decline over hours, signs of sepsis

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6
Q

Which causative agents are most common if <3 months

A
Group B Strep (40%)
G –ve bacilli (14%)
S. pneum (14%)
N. mening (12%)
E. coli (neonates)
Listeria monocytogenes (neonates)
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7
Q

Which causative agents are most common if 3 months to 3 years?

A

S pneum (45%)
N mening (34%)
Group β strep (11%)
G –ve bacilli (9%)

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8
Q

Which causative agents are most common if 3 - 10 years old?

A
S pneum (47%)
N mening (32%)
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9
Q

Which causative agents are most common if 10-19 years old?

A

N mening (55%)

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10
Q

What key things should be considered in a history of ? meningitis?

A

Lethargy? Confusion?

Birth history - hydrocephalus?
PMH - immunocompromised? risk factors?
DH - Recent antibiotics? Full course?
Immunisations
FH - anyone else?
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11
Q

How much fluid should you give a child in shock/sepsis?

A

20mls/kg - 1/4 circulating vol

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12
Q

What are the key signs of meningism?

A

Neck stiffness
Photophobia
Headache

+ Vomiting
+ fever

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13
Q

What added signs may you see in a baby with ? meningitis?

A

Bulging fontanel

High pitched screaming cry

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14
Q

What two signs can be elicited to show meningism?

A

Kernigs sign - lie down with hip flexed at 90 degrees, flex knee - pain?
Brudzinski’s sign - lie down, lift neck, knees bend up too

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15
Q

What investigations would you do in ? meningitis?

A
  • FBC - WCC can be high or low, Neutropoenia - bad sign
  • Culture
  • Capillary blood gas (less painful)
  • CRP (increased in bacterial)
  • U&Es
  • BM (low sugar can cause confusion)
  • Lumbar puncture
  • Full neuro exam
  • meningococcal PCR (more sensitive)
  • Throat swab (old fashioned)
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16
Q

What should normal CSF look like from a lumbar puncture?

A

Gin clear

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17
Q

What would make you hold off doing a lumbar puncture?

A

Reduced GCS - confusion sign of raised ICP
Papilloedema
High Bp

  • If high ICP and you do a lumbar puncture - causes you to cone - fatal
18
Q

If a child with ? meningitis comes into your GP, what do you do?

A

Call 999
Give IM pennicillin
Give supportive care - paracetamol
Communicate - warn A+E peads

19
Q

What signs of shock can you look for in a child ?

A

Slow cap refil
Low Bp (children keep this high until very late)
High HR
Urine output - should be 1ml/kg/hour

20
Q

What is the aim of meddication in meningitis?

A

Erradicate infection
Reduce morbidity
Prevent complications

21
Q

What medication would you give to:

- Neonate with meningitis?

A

Ampicillin + an aminoglycoside or Cephalosporin

22
Q

What medication would you give to:

- <3 month old with meningitis?

A

Ampicillin + Cephalosporin (Ceftriaxone/Cefotaxime)

23
Q

What medication would you give to:

- 3 years + with meningitis?

A

Cephalosporin (ceftriaxone/cefotaxime)

24
Q

What is the thinking re: giving or not giving steroids with antibiotics in meningitis?

A

Reduce inflammation but uncertain

If given with 1st antibiotics - ? reduced hearing loss/long term neuro effect

25
Q

When is a rash seen in meningitis?

A

When it develops into mengiococcal Septicaemia

26
Q

What does an aseptic meningitis mean?

A

The CSF is sterile - usually viral

27
Q

What types of bacteria are likely causes of meningitis int he elderly?

A

S. pneumonia

Listeria monocytogenes

28
Q

What is the usual source of meningitis infection?

A

Via the blood stream

can be due to local extension, direct implantation + via the peripheral NS eg. rabies

29
Q

What are the key CSF findings in bacterial meningitis?

A
Cloudy
High polymorphs
High neutrophils
High protein
Low glucose
Gram stain +ve
30
Q

What are the complications of meningitis (esp. bacterial)

A
Severe sepsis + death
Cerebral oedema
Cerebra thrombophlebitis
Permenant neuro complications - eg. hearing impairment
Abcess
Subdural empyema
Obstructive hydrocephalus
31
Q

What are likely viral causative agents of meningitis?

A

enteroviruses (85%): Coxsachie, Echo, polio-virus - most in summer

Mumps, measles
Herpes virus (HPV + varicella)
HIV

32
Q

What are the key CSF findings in viral meningitis?

A

CSF - Clear
Slightly high protein
Normal glucose
High lymphocytes

33
Q

What are the possible routes of entry of a CNS infection?

A

Direct implantation - trauma, iatrogenic, congenital lack of Blood-brain-barrier)

Local extension of established infection - sinuses, teeth, ear infection

Peripheral NS - Rabies, herpes, shingles.. Rare

Blood - via capillaries in the parenchyma or at choroid plexus - must cross BMEC - Brain microvascular endothelial cells

34
Q

Where is it easier for an infection to cross the BMEC?

A

At the choroid plexus

  • capillaries have fenestrations - increased permiablility - weaker tight junctions + weaker electrical resistance
  • increased transcellular flux
  • easier for infection to cross into brain
35
Q

What cell type surrounds the endothelium of capillaries in the brain parenchyma BMEC?

What makes it harder for infection to cross?

A
  • Astrocyte cells - foot wraps around it
  • Endothelum has strong tight junctions - Less paracellular flux
  • Slow rate of fluid phase endocytosis - less transcellular flux
36
Q

Overall what is the most common bacterial cause of meningitis?

A

Neisseria meningitidis

37
Q

What type of bacteria does the Men C and Men B vaccine act against?

A

Neisseria Meningitidis

38
Q

What does the PCV13 and PPV23 vaccine act against in meningitis?

A

Strains of Streptococcus Pneumoniae

39
Q

What does the Hib vaccine vaccinate against?

A

Haemophilis Influenzae B

40
Q

How much protection does BCG vaccine give against meningitis?

A

75% protection

41
Q

What causes fungal meningitis? What are the symptoms?

A

Cryptococcus neoformans

Gradual onset
In pts with impaired cellular immunity
India ink stain +ve

42
Q

What is the most common cause of encaphalitis?

A

HSV - Herpes simplex virus
70% mortality if untreated
Extensive asymmetric necrosis of temporal lobes