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PATHOLOGY CAM304 > CNS infections AR > Flashcards

CNS infections AR Flashcards

1
Q

Name some CNS infections

A 
Encephalitis
Meningitis
Epidural Abscess
Cerebral Abscess
VP shunt infection
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2
Q

Some non infectious conditions which mimic CNS infections are:

A

Neoplastic disease
Intracranial tumours and cysts
Medications
Collagen Vascular Disease

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3
Q

What is Meningitis?

A

Meningitis -> inflammation of the meninges

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4
Q

What is meningitis characterised by?

A

Fever and headaches

Meningismus and altered mental state

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5
Q

What is a clinical diagnostic sign?

A

Cerebrospinal leucocytosis (>6WCC)

  • ASeptic
  • Purulent
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6
Q

Common Pathogens in 18-50 yo’s for Meningitis??

A

Streptococcus pneumoniae

Neisseria meningitidis

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7
Q

Common Pathogens in immunocompromised for Meningitis??

A

Streptococcus pneumoniae
Neisseria meningitidis +
Listeria monocytogenes

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8
Q

What is the pathogenesis of BACTERIAL meningitis?

A

Initial colonisation of mucosal surfaces including nasopharynx by haematogenous or contiguous spread

  • Specific antibody is an important defence
  • After bacterial invasion of the meninges, REPLICATION WITHIN THE SUBARACHNOID SPACE LEADS TO AN INFLAMMATORY RESPONSE
  • Levels of inflammatory cytokines are proportional to the severity of symptoms and risk of adverse outcome, suggesting role of adjunctive steroids
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9
Q

Meningitis Causal Organisms in Neonates

A

E.coli

Group B strep

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10
Q

In Pregnant women what are causal bacterial organisms?

A

L.monocytogenes

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11
Q

In unvaccinated children what can cause meningitis?

A

HAEMOPHYLUS INFLUENZAE TYPE B

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12
Q

What is the pathogenesis of VIRAL meningitis?

A

Virus infection of the mucosal surfaces of the RESPIRATORY OR GIT tract

Followed by viral multiplication in tonsillar or gut lymphatics

Viraemia with haematogenous dissemination to CNS leads to meningeal inflammation

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13
Q

Causal VIRAL organisms

A

HSV (aseptic meningitis)
Enteroviruses (80%)
Other: VZV, Mumps, HIV

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14
Q

What are some additional risk factors for bacterial meningitis?

A 
Adults >60
Children <5
People with sickle cell anaemia
People recieving chemo
Immunosuppressed
Diabetics
Exposure to meningitis
People living in close quarters (military barracks, dormitorys)
IVDU
People with shunts in place for hydrocephalus
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15
Q

Classic symptoms of meningitis:

A

Fever, headache, STIFF NECK

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16
Q

What are some SYMPTOMS of Bacterial meningitis

A 
Onset often abrupt
Vomiting
PHOTOPHOBIA
convulsions
Irritability
Apathy
Drowsiness
Unconsiousness
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17
Q

What are some SIGNS of Bacterial meningitis

A

NEck and spinal stiffness

Pain and resistance on extending the knee when thigh is flexed- KERNIG’s SIGN

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18
Q

What would you want to differentiate between?

A

Subarachnoid haemorrhage

Cerebral abscess

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19
Q

What are the SYMPTOMS of VIRAL meningitis?

A

Commonly consitutional

  • Diarrhoea
  • Fever
  • Vomitting
  • Anorexia
  • Rash
  • Cough
  • Myalgia

HSV-2 associated with primary genital herpes

Enteroviral syndromes seasonal- include hand, foot and mouth disease

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20
Q

What is Brudzinski’s sign?

A

Severe neck stifness cause a patients hips and knees to flex wihen the neck is flexed

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21
Q

How do you diagnose Meningitis?

A

LUMBAR PUNCTURE:

For removal and analysis of CSF

22
Q

what are some of the complications of Lumbar punctures?

A

Headache - 10-25%
Traumatic Tap 20%
Brain herniation : CAUTION IF: GCS <11, Brain stem signs, very recent seizure

23
Q

When would you use a CT of the brain?

A
  • immunosuppresed
  • History of CNS disease
  • New onset siezure
  • Abnormal level of consciousness
  • Papilloedema
  • Focal neurological defect
24
Q

What tests would you perform on the CSF fluid from the LP?

A

ROUTINE TESTS:

  • WBC count with differential
  • RBC count
  • Glucose concentration
  • Protein concentration
  • Gram Stain
  • Bacterial Culture

SPECIFIC TESTS

  • Viral PCR/Culture
  • AFB smears
  • VDRL
  • India ink and cryptococcus antigen
  • Fungal Culture
  • Antibody tests
  • Cytology and flow cytometry
25
Q

What are some CSF findings in patients with VIRAL MENINGITIS?

ie. what would WBCC be
- Cell type
- Glycose
- Protein

A

WBC: 50-1000
Cell Type: Increased LYMPHOCYTES
Glucose: NORMAL
Protein: NORMAL

26
Q

What are some CSF findings in patients with BACTERIAL MENINGITIS?

ie. what would WBCC be
- Cell type
- Glycose
- Protein

A

WBC: 100->10000
Cell Type: Increased NEUTROPHILS
Glucose: 6g/l

27
Q

What are some CSF findings in patients with TB associated MENINGITIS?

ie. what would WBCC be
- Cell type
- Glycose
- Protein

A

WBC: 50-300
Cell Type: Increased LYMPHOCYTES
Glucose: <60% blood level
Protein: elevated

28
Q

PRogressive steps in MANAGEMENT OF MENINGITIS

A

Severe headache & fever ->
1. Blood Culture + IV penicillin
2. CT - check intracranial pressure
& LP if no evidence of raised ICP

29
Q

If LP shows LYMPHOCYTES predominate->

A

(a) & photophobia- viral meningitis -> PCR and CSF (for enterovirus)
(b) If consciousness or cognitive state impaired but NO meningism -> ENCEPHALITIS likely -> measure glucose, sodium and calcium - give IC aciclovir

30
Q

If LP shows NEUTROPHILS predominate->

A

Bacterial meningitis likely
->
Causative organism identified on gram stain of CSF -> specific therapy is necessary

if not identified - give CEFTRIAXONE

31
Q

What are common SEQUELAE of meningitis? (5)

A
    • NOTE - the strongest risk factors for an unfavourable outcome are those indicative of systemic compromise:
  • Impaired consciousness
  • Low white-cell count in the cerebrospinal fluid
  • Infection with S. pneumoniae
  1. Encephalopathy (altered cerebral function and convulsion)
  2. Cranial nerve palsies
  3. Cerebral infarction or abscess
  4. Obstructive hydrocephalus (from basal obstruction of CSF)
  5. Subdural effusion of sterile or infected fluid
  6. Transtentorial herniation - caused by swelling of brain
32
Q

What is the empirical treatment for Bacterial meningitis?

A

Benzylpenicillin dosage **
10 : 1.2 g

PLUS
Dexamethasone (10mg IV) (not Use VANCOMYCIN

33
Q

What is meningococcus?

A

Neisseria meningitidis, a bacteria that causes meningitis - ie.meningococcal

34
Q

Neisseria meningitidis- who does it affect?

A

Affects all ages- most common in children and young adults

Serotypes A,B, C associated with most morbidity and mortality

35
Q 
Neisseria meningitidis-
Incubation period?
Source?
Spread?
Carriage rate?
Route of INFECTION?
Defence mechanisms?
A

Incubation period: Short , 3 days
Source: Nasopharynx
Spread: via infected respiratory secretions
Carraige rate: 1/10 people
Route of infection: nasopharynx-> blood stream -> meninges
*during meningococcaemia a characteristic petechial rash is a common finding
Defence mechanism: possession of antibodies bactericidal to the invasive strain -

36
Q

What is the microbiology of Neisseria meningitidis?

GRAM ->?

A

Gram NEGATIVE
Have Pili- attachment- undergo phsic and antigenic variation

Smooth moist colonies , glistening surfaces

37
Q

What is the CULTURE of Neisseria meningitidis?
GRAM ->?
Oxidase +/-

A

Strict aerobe
Fastidious
Complex growth requirements
Identify: biochemical testing- oxidase +

38
Q

When would you use multiplex PCR?

A

When patietns have already recieved ABX

39
Q

What prophylaxis would you give household members/close contacts to a person who has meningitis?

A

RIFAMPICIN
or
CEFTRIAXONE

40
Q

What vaccine do you get at 12 months?

A

Meningococcal C conjugate vaccine
92% effective in protecting toddlers
97% effective in teenagers.

Meningococcal quadrivalent Polysacharide vacines are 85% protective in adults, and usually for people at higher risks

41
Q

What is a common cause of Meningococcal in Infants and pre school children?
Which type?
Is there a vaccination

A

HAEMOPHILUS INFLUENZAE
type B

Vaccination at 2,4,6 months!

42
Q

What can you get post penumococcal infection?

A

S. pneumoniae meningitidis

  • often sequel f pneumococcal infection of lungs, sinus or middle ear (40% of cases)
  • Aggressive
43
Q

what are the virulence factors of S.pneumoniae

A 
Adherance
Invasion
Tissue Damage
Phagocytic survival
>90 serotypes
44
Q

What are the fatalaty rates for pneumococcal meningitis?
Long term sequelae?
What treatment?

A

19-37% fatality rate
In up to 30% of survivors, long term neurologic sequelae develop (heairng loss and other focal neurological deficits)

MIC to penicillin and ceftriaxone required
21 days of treatment

45
Q

What are the 2 types of pneumoccocal vaccination?

A

POLYSACCARIDE VACCINE
- + mature B lymphocytes- not T lymphocytes)
- polysaccharides form the capsules of 23 of the most virulent, invasive disease.
- ADULTS should get given.
Given to aboriginal children 18-24m onths and patients at risk at 15-65 years + all people >65

CONJUGATE VACCINE
- A t helper cell response
- 13 strains
- Good response in infants (95% efficacy)
- Given at 2 months, 4 months and 6 months
-

46
Q

What adjunctive therapy would you give in pneumococcal meningitis?

A

STEROIDS- DEXAMETHASONE (reduces risk of unfavourable outcome)

47
Q

Rare causes of Meningitis

A 
Listeria monocytogenes
aerobic
non spore forming
Gram positive rod
enters peyers patches of LIVER
48
Q

Presentation of Listeria meningitis

A

Healthy adults: bacteremia with or without high grade fever, or mild flu like illness

Pregnancy: fever/back pain- > can result in SPONTANEOUS ABORTION

Neonates: granulomatosis infantiseptica
- Late onset death

49
Q

Lab investigations of Listeria meningitis

A

Lab investigation
- Get vaginal swab, CSF, blood culture

CSF microscopy
Culture- BETA HEMOLYTIC, tumbling motility

50
Q

Summary for MENINGITIS:

Presentation

A 
Headache
vomiting
fever
irritability
drowsiness
rash
51
Q

Summary for Meningitis

Diagnosis

A

CSF
Blood culture
PCR
Serology

52
Q

Management

A

IV ABX
RIFAMPICIN to close contact
Steroids
Vaccination

PATHOLOGY CAM304 (16 decks)

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