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MD4001 Week 3 > 7. Infections of the CNS > Flashcards

7. Infections of the CNS Flashcards

1
Q

Glass test, non blanching is….

A

A rash that does not fade under pressure is a sign of meningococcal septicaemia

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2
Q

Clinical features of meningitis?

A

Headache, sore throat, drowsiness

Intravascular coagulation, endotoxaemia, shock, multi-organ failure, raised intracranial pressure

Rapid onset fever, photophobia, neck stiffness (typically viral)

Level of consciousness falls (typically viral)

Petechial or purpuric rash (typically viral)

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3
Q

Symptoms of meningitis mainly seen in babies?

A

Tense/bulging soft spot on their head
Refusing to feed
Irritable when picked up, with a high pitched or moaning cry
A stiff body with jerky movements, or else floppy and lifeless

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4
Q

Which features of meningitis are more specific a viral origin?

A

Rapid onset fever, photophobia, neck stiffness (typically viral)

Level of consciousness falls (typically viral)

Petechial or purpuric rash (typically viral)

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5
Q

Encephalitis is…

A

Inflammation of the brain

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6
Q

Sepsis is…

A

Whole body inflammation when your body goes into a system inflammatory response syndrome (SIRS)

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7
Q

3 methods of invasion into the CNS by micro organised?

A

BBB
B- CSF BARRIER
Direct spread

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8
Q

Mechanism of invasion to CNS by micro-organisms via the BBB?

Breach results in….

A

– Created by tightly packed endothelial cells lining the blood
vessels in the brain.
– Endothelial cells mechanically supported by thin basement membrane.
– Breach by infectious agents causes ENCEPHALITIS.

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9
Q

Mechanism of invasion to CNS by micro-organisms via B-CSF barrier?
Breach results in….

A

– Similar barrier at arachnoid membrane and in ventricles. – Breach by infectious agents causes meningitis.

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10
Q

Mechanism of invasion to CNS by micro-organisms via direct spread?

A

From sinuses, otitis media and skull fractures

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11
Q

What laboratory investigations should be done to confirm a diagnosis for infections of the CNS?

A

Blood test, such as:

  • Culture
  • NAAT
  • Glucose
  • FBC
  • U&E
  • Clotting

CSF test, such as:

  • White cell count
  • Gram stain
  • Ziehl-neelsen stain (
  • India ink
  • NAAT
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12
Q

Which diseases does the ziehl neelsen stain and the india ink stain identify?

A

Ziehl-neelsen= Tb

India ink= India ink staining of cerebrospinal fluid is a sensitive test for the presence of cryptococcus neoformans.

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13
Q

When should a lumbar puncture not be done?

A

Supratentorial and infratentoral pressure difference

Infeciton of the skin overlying the needle entry site

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14
Q

Name 4 bacterial infections causing meningitis?

A

Neisseria meningitidis
Haemophilus influenzae
Streptococcus pneumoniae
Mycobacterium tuberculosis

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15
Q

Name 5 viral infections causing meningitis?
3 x enteroviruses
1 x herpes
1 x paramyxovirus

A

Enteroviruses:
• Echovirus
• Coxsackie viruses A & B
• poliovirus

Herpes viruses:
• Herpes simplex 1& 2

Paramyxovirus:
• Complication of mumps

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16
Q

Fungal infections causing meningitis

A

Cryptococcus neoformans

** India ink stain**

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17
Q

3 protozoa infections causing meningitis?

A

Amoebae
Naegleria
Acanthamoeba

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18
Q 
Characteristics of Neisseria meningitidis as a meningococcal disease:
Gram....
Infects only.... where does it lie....
Transmission...
Strains...
A
  • Gram negative. Intracellular diplococus
  • Only infects humans. Exists as normal microbiota in nasopharynx
  • Transmission by droplet spread or direct contact from carriers
  • 5 strains – A, B, C, W135, Y
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19
Q 
Characteristics of Haemophilus influenze as a meningococcal disease:
Gram..
Structure...
Serotypes...
Most virulent strain is?
A
  • Gram-negative
  • Coccobacilli (spherical)
  • Six capsular serotypes (a-f) known to cause disease
  • Most virulent strain is H. influenzae type b (Hib)
20
Q 
Characteristics of streptococcus pneumoniae as a meningococcal disease:
Type of disease?
Shape?
Gram?
Where found?
A
  • Pneumococcal disease
  • Chains of cocci
  • Gram positive
  • Exists as normal microbiota in nasopharynx
  • Also causes pneumonia, otitis media
21
Q

Virulence factors of bacterial meningitis?

A
  • Anti-phagocytic polysaccharide capsule
  • Endotoxin (released when disintegrates)
  • IgA protease
  • Outer membrane proteins (OMPs)
  • Pili (fimbriae)
22
Q

Cloudy CSF indicates

A

Bacterial meningitis infection

23
Q

What is the significance of age in predicting a diagnosis of meningitis?

A

Ages most at risk are:
2 months -4 years
65yrs-79yrs

24
Q

Which bacterial meningeal pathogens are responsible for meningitis in neonates?

A

Escherichia coli

Group B Streptococcus Listeria monocytogenes

25
Q

Which bacterial meningeal pathogens are responsible for meningitis in <5 yrs old?

A

Neisseria meningitidis Haemophilus influenzae

26
Q

Which bacterial meningeal pathogens are responsible for meningitis in young adults?

A

Neisseria meningitidis

27
Q

Which bacterial meningeal pathogens are responsible for meningitis in older?

A

Streptococcus pneumoniae Listeria monocytogenes

28
Q

Which bacterial meningeal pathogens are responsible for meningitis in immunosuppressed?

A

Mycobacterium tuberculosis Cryptococcus neoformans

29
Q

Early onset of neonatal meningitis:
When?
Due to?
Risks associated?

A

• Occurs <7 days

• Infected by heavily
colonised mother

Risks:
• Premature rupture of membranes
• Pretermdelivery
• 60% fatality rate

30
Q

Late onset of neonatal meningitis:
When?
Due to?
Risks associated?

A

• Occurs <3 months

Cause:
• Lack of maternal
antibody
• Poor hygiene in nursery

• 20% fatality rate

31
Q

Complications of bacterial meningitis?

A
  • Sepsis
  • Intellectual deficit
  • Deafness
  • Arthritis
  • Skin necrosis
32
Q

When treating suspected bacterial meningitis, what is given?

A

IV broad spectrum antibiotics e.g. ceftiaxone, cefotaxime, ceftriaxone, amoxicillin and gentamicin

33
Q

What is the main method for prevention of meningitis spread?

A 
VACCINES e.g.
• MenC (meningococcal group C)
• Hib (Haemophilus influenzae type B)
• BCG (Mycobacterium tuberculosis)
• Strep. Pneumoniae (pneumonococcal)
• MenB (meningococcal group B)
• Men ACWY (quadrivalent)
34
Q

Notification, Prevention and Control strategy for meningitis?

A

Meningococcal disease is a notifiable disease under the Public Health etc. (Scotland) Act 2008.

Reference Laboratories:
• Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory (SHLMPRL)

Public Health Action:
• Public Health will identify the close contacts and arrange antibiotics. Vaccination may also be required.
• If the patient is a child at school information letters and MRF info leaflets for all school parents are arranged.

Public Awareness:
• The public should be aware of the key signs and symptoms and to seek urgent medical advice if concerned.

35
Q 
Viral meningitis:
Common?
Diagnostic tool?
Treatment?
Vaccine available?
A
  • Milder disease than bacterial but more common
  • NAAT is a valuable diagnostic tool. Identify in faeces, urine, CSF, serology
  • No specific treatment
  • Aciclovir (herpes)

• Use of vaccination (polio)

36
Q 
Tuberculous meningitis:
Associated with which disease?
Cause?
Diagnosis?
Treatment?
Vaccine?
A
  • Frequently associated with miliary TB
  • Usually develops when Rich focus discharges contents in sub-arachnoid space
  • Acid-fast bacilli in CSF smear. NAAT and culture from CSF
  • Treated with rifampicin, isonazid, pyrazinamide, ethambutol
  • Vaccination with BCG
37
Q

Encephalitis (infection to CNS):
Origin?
Primary vs secondary?

A

• Usually viral in origin. Viruses gain access to CNS via blood or neurons

• Primary encephalitis
– First exposure to virus results in virus directly
affecting brain / spinal cord

• Secondary encephalitis
– Virus first infects another part of body, then affects CNS when reactivated

38
Q

Signs of cerebral dysfunction in encephalitis>

A 
– Abnormal behaviour
– Seizures
– Altered consciousness
– Nausea
– Vomiting
– Fever
39
Q

How does a brain abscess form?

A

Beings as diffuse inflammation of brain matter progressing to a focal lesion.
Arise from pia mater suppuration

(Can be visualised by MRI or CT)

40
Q

Diagnosis of brain abscess?

A

Culture from aspiration pus

41
Q

Brain Abscess - Causes and predisposing factors?

A

• Predisposing factors
– Otitis media (ear inflammation)
– Mastoiditis
– Sinusitis

Cause:
• Oral-nasopharyngeal microbiota
– Aerobic (S. aureus, Strep. milleri)
– Anaerobic (Bacteroides sp., Fusobacterium sp.)
• Immunocompromised (eg. HIV, transplantation)
– Protozoa (Toxoplasma gondii)
– Fungi (Candida sp., Nocardia sp., Aspergillus sp.)

42
Q

What is a TSE?

A

Transmissible spongiform encephalopathies

Prion disease i.e. cause of brain disease, have no nucleus, not visible under microscope

43
Q

TSE that affect humans

A

• Affects humans…
– Creutzfeldt-Jakob disease (CJD)
– New variant Creutzfeldt-Jakob disease (nvCJD)

44
Q

Direct damage to nerve cells in…

A

poliomyelitis

45
Q

• Release of neurotoxins released at a distant site by bacteria, name 2 diseases this occurs in

A

(eg. botulism, tetanus)

MD4001 Week 3 (12 decks)

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