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Pathology by week > W10 - CNS infections + meningitis > Flashcards

W10 - CNS infections + meningitis Flashcards

1
Q

What are the 4 routes of entry for pathogens to CNS?

A
  1. Haematogenous spread (most common)
  2. Direct implantation - i.e. trauma, surgery
  3. Local extension - 2ndary to established infections i.e. externa otitis spread to mastoid and then CNS
  4. PNS into CNS - viruses, i.e. rabies
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2
Q

What CNS region is inflamed in meningitis?

A

Inflammatory process of meninges + CSF

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3
Q

What CNS region is inflamed in meningoencephalitis?

A

Inflammation of meninges + brain parenchyma

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4
Q

What is the mortality rate of meningitis? What is the main neurological sequelae in meningitis survivors?

A

10% mortality
5% of survivors develop sensorineural deafness

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5
Q

What are the symptoms (9) of meningitis?

A
  1. Fever
  2. Headache
  3. Neck stiffness
  4. Photophobia
  5. Drowsiness
  6. Vomiting
  7. Joint pain
  8. Fits
  9. Rash (non-blanching, due to meningococcal meningitis)
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6
Q

6 causative agents of acute meningitis

A

Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae
Listeria monocytogenes
Group B Streptococcus
Escherichia coli

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7
Q

With N. meningitides, what % of infected individuals have meningitis only, septicaemia only, and meningitis + septicaemia

Why is this important?

A

50% meningitis
10% septicaemia
40% septicaemia AND meningitis

have to see if patient has signs of septicaemia => if YES, DO NOT PROCEED TO DO LUMBAR PUNCTURE B/C THEY MIGHT HAVE ABNORMAL CLOTTING.

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8
Q

If untreated, how does septicaemia proceed?

A

Capillary leak => hypovolaemia
Deranged coagulopathy => bleeding + thrombosis
Metabolic derangement => usually acidosis
finally, myocardial failure => MOF

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9
Q

What is the main cause of chronic meningitis? What is seen on scans?

A

Tuberculous chronic meningitis
=> tuberculous granumolas, tuberculous abscesses

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11
Q

Aseptic meningitis:

A) How do patients present?

B) What is the most likely cause?

C) What is the clinical course usually?

A

A) headache, neck stiffness, photophobia, sometimes a non-specific rash

B) Most commonly due to Enteroviruses Coxsackievirus group B or Echoviruses

  • 2nd most common cause herpes simplex virus 1 or 2

C) self-limited and resolves in 1-2 weeks

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12
Q

How does N meningitiidis spread?

A

From person-to-person, from asymptomatic carriers (through nasopharyngeal mucosa in susceptible individual)

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13
Q

How does encephalitis usually spread?

A

caused by virus and transmission is commonly either person-to-person, or through vectors: monsquitoes, lice, or ticks

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14
Q

What are the common viruses that cause encephalitis?

A

1) HSV 1 & 2
2) Measles, mumps
3) Varicella zoster
4) EBV/CMV
5) Enteroviruses (Coxsackie A & B; Echovirus; polio)
6) Rabies
- Now on a rise: West Nile River (WNR) virus

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15
Q

What do you consider in a person who appears to have encephalitis but is enterovirus (-) and herpes (-)?

A

Consider WNV as a cause!

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16
Q

Name bacterial (1), amoebic (2), and protozoic (1) causes of encephalitis

A

Bacteria:

  1. Listeria monocytogenes (usually in immunocompromised)

Amoeba:

  1. Naegleria fowleri (habitat warm water)
  2. Acanthamoeba species => also causes brain abscess, aseptic or chronic meningitis

Protozoa:

  1. Toxoplasma gondii (which causes toxoplasmosis)
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17
Q

How does toxoplasmosis spread?

A
  1. Ingestion (raw meat; undercooked meat; oocytes from contact with cat litter/soil)
  2. Transplacental (mom to fetus)
  3. Organ transplantation
18
Q

What are the aetiology (5) of brain abscesses?

A
  1. Otitis media
  2. Mastoiditis
  3. Paranasal sinuses
  4. Endocarditis
  5. Haematogenously
19
Q

What are the common infectious agents (6) present in brain abscesses?

A
  1. Streptococci (both aerobic and anaerobic)
  2. Staphylococci,
  3. Gram-negative organisms. (particularly in neonates)
  4. Mycobacterium tuberculosis
  5. fungi
  6. parasites

NOTE how 1 & 2 are the common causes of infective endocarditis as well

20
Q

Name 1 common form of vertebral infections

A

Pyogenic vertebral osteomyelitis

21
Q

Name 3 ways in which infection can spread to vertebrae to cause spinal infections

A
  1. Direct open spinal trauma
  2. from infections in adjacent structures
  3. Haematogenous spread
22
Q

What are 7 risk factors for developing spinal infections?

A
  1. advanced age
  2. IVDU
  3. long-term systemic steroids
  4. diabetes mellitus
  5. Organ transplantation
  6. Malnutrition
  7. Cancer
23
Q

______ is superior to ______ in detecting parenchymal abnormalities such as abscesses and infarctions.

A

MRI is superior to CT

24
Q

In CSF studies; what is neutrophils and what is lymphocytes associated with?

A

Neutrophils = bacterial meningitis

Lymphocytes = viral meningitis

25
Q

Describe the following for bacterial meningitis:

colour

cells/L

G stain

protein (g/l)

glucose (mmol/l)

A

colour = turbid, purulent

cells/L = 100-2000 polymorphs

G stain = + results

protein (g/l) = 0.5-3.0 g/L

glucose (mmol/l) = 0.2-2 mmol/L

26
Q

Describe the following for aseptic meningitis:

colour

cells/L

G stain

protein (g/l)

glucose (mmol/l)

Name 4 causes

A

colour = clear or slightly turbid

cells/L = 15-500 lymphocytes

G stain = NEGATIVE results

protein (g/l) = 0.5-1.0 g/L

glucose (mmol/l) = Normal (2.2-3.3)

causes: viral meningiits, partially antibiotic treated bacterial meningitis, encephalitis, brain abscess

27
Q

Describe the following for TB meningitis:

colour

cells/L

G stain

protein (g/l)

glucose (mmol/l)

A

colour = clear or slightly turbid

cells/L = 30-500 lymphocytes or some polymorphs

G stain = NEGATIVE results, SCANTY ACID FAST BACILLI

protein (g/l) = 1.0-6.0 g/L

glucose (mmol/l) = 0.2-2 mmol/L

causes: TB meningitis, brain abscess, cryptococcal meningitis

28
Q

A 20 year old woman presents with headache and neck stiffness.

What do you see? What is the causative pathogen?

A

Gram + diplococci

streptococcus pneumoniae

29
Q

A 18 year old man present with headache and neck stiffness. What do you see? What is the causative pathogen?

A

Gram negative cocci

Neisseria meningitidis

30
Q

A 65 year old presents with headache and neck stiffness. What do you see? What is the causative pathogen?

A

Gram positive rod

Listeria monocytogenes

31
Q

A 45 year old presents with headache and neck stiffness. What stain is this? What is the causative pathogen?

A

Ziehl-Neelson stain

mycobacterium tuberculosis

32
Q

A 35 year old presents with headache and neck stiffness. What stain is this? What is the causative pathogen?

A

India ink stain

encapsulated yeast = cryptococcus neoformans

33
Q

Describe a normal CSF study in terms of:

colour

cells/L

G stain

protein (g/l)

glucose (mmol/l)

A

colour = clear

cells/L = 0-5 leukocytes

G stain = NEGATIVE

protein (g/l) = 0.15-0.4 g/L

glucose (mmol/l) = 60% blood glucose level, usually 2.2-3.3 mmol/L

39
Q

Highly suspected meningitis, awaiting culture results. Which abx do you treat with?

A

Ceftriaxone 2g IV BD

if >50years or immunocompromised add: Amoxicillin 2g IV 4hourly

40
Q

Suspected meningo-encephalitis, awaiting culture results. What treatment do you give?

A

Aciclovir 10 mg/kg IV TDS

Ceftriaxone 2g IV BD

If >50years or immunocompromised, add: Amoxicillin 2g IV 4 hourly

Pathology by week (70 decks)

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