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Week 7 - Clinical Microbiology & Infections 2 > Infection of the CNS > Flashcards

Infection of the CNS Flashcards

1
Q

CNS infections can be classified anatomically or aetiologically. What are the 4 types of CNS infections under the anatomical classification? [4]

A
  1. Meningitis (Bacterial, Viral)
  2. Encephalitis/Meningo-encephalitis (Viral, Bacterial)
  3. Mass lesion (abscess)
  4. Myelitis C
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2
Q

Define meningitis [1]

A

inflammation of meninges +/- cerebrum (meningo-encephalitis) with inflammatory CSF

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3
Q

Define encephalitis and meningo-encephalitis [2]

A
  1. encephalitis = inflammation of the brain
  2. meningo-encephalitis = inflammation of the brain and meninges
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4
Q

Define myelitis [1]

A

infection of the spinal cord

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5
Q

What CNS syndromes are caused by bacteria [3] and what are the most common bacteria that cause these syndromes? [3]

A
  • CNS Syndromes:
    1. meningitis
    2. meningo-encephalitis
    3. abscess
  • Causative Bacteria:
    1. meningococcus,
    2. pneumococcus
    3. listeria
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6
Q

What CNS syndromes are caused by viruses [2] and what are the most common viruses that cause these syndromes? [5]

A
  • CNS Syndromes:
    1. encephalitis
    2. meningitis
  • Causative Viruses:
    1. herpes simplex virus (HSV)
    2. varicella zoster virus (VZV)
    3. enterovirus (D-68)
    4. HIV
    5. mumps
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7
Q

What CNS syndromes are caused by fungi [2] and what is the most common fungi that cause these syndromes? [1]

A
  • CNS Syndromes:
    1. meningo-encephalitis
    2. mass lesion
  • Causative Fungi:
    1. cryptococcosis
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8
Q

What CNS syndromes are caused by protozoa [2] and what is the most common protozoa that cause these syndromes? [1]

A
  • CNS Syndromes:
    1. mass lesion
    2. eosinophilic-meningitis
  • Causative Protozoa:
    1. toxoplasmosis
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9
Q

What are the signs & symptoms of meningitis? [4]

A
  • 95% will have 2 of:
    1. headache
    2. neck stiffness
    3. reduced GCS
    4. fever
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10
Q

What is confusion indicative of in a patient with suspected meningitis? [2]

A
  1. cerebritis
  2. encephalitis
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11
Q

What kind of rash do you typically get with meningitis? [3]

A

purpuric and/or petechial but macular early on (meningococcal)

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12
Q

What are the 3 major bacterial causes of meningitis (including what type of bacteria each are)? [6]

A
  1. Gram positive diplococci → streptococcus pneumoniae
  2. Gram negative diplococci → neisseria meningitidis
  3. Gram positives rods → listeria monocytogenes
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13
Q

Meningitis in travellers tend to be caused by…? [1]

A

resistant, non-endemic disease

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14
Q

Meningitis in alcoholics and people with hearing aid transplants tend to be caused by…? [1]

A

pneumococcal disease

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15
Q

Meningitis in IVDUs tend to be caused by…? [2]

A
  1. staphylococcus aureus
  2. streptococcus
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16
Q

Meningitis in people coming back from pilgrimage (Hajj) tend to be caused by…? [1]

A

meningococcal disease

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17
Q

What factors put people at increased risk of developing pneumococcal brain meningitis? [5]

A
  1. Middle ear disease
  2. Head injury (CSF leak)
  3. Neurosurgery
  4. Alcohol
  5. Immunosuppression (HIV)
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18
Q

What factors put people at increased risk of brain meningitis caused by listeria? [2]

A
  1. immunosuppression
  2. pregnancy
19
Q

Pneumococcal meningitis is more severe. What are the typical signs of pneumococcal meningitis? [6]

A
  • Neurology
    1. focal signs (65%)
    2. seizures (24%)
    3. VIII palsy (22%)
  • CAP - community acquired pneumonia
  • ENT - ear, nose & throat infection
  • Endocarditis
20
Q

What factors predisposes people to have a worse outcome in a bacterial meningitis infection? [6]

A
  1. Pneumococcus
  2. Reduced GCS
  3. CNS signs
  4. Older age (>60 years)
  5. CN palsy (Pneumococcal)
  6. Bleeding (Meningococcal)
21
Q

What investigations should be done on a patient with suspected meningitis? [6]

A
  1. History and exam
    • typical presentation = headache and neck pain
    • examine throat and examine for Cervical LNs
      • if there is pus on the tonsils, it’s a group A strep infection, not meningococcus
  2. Blood cultures (blood PCR)
  3. Throat culture, Viral gargle
  4. FBC, UEs, LFTs, CRP
  5. Lumbar puncture (LP) - examining CSF
    • Cell count, Gram stain, Culture and PCR
    • Protein and Glucose
    • Viral PCR
22
Q

What is a CT scan used to exclude when investigating a patient with suspected meningitis? [2]

A
  1. mass lesion/mass effect
  2. gross cerebral oedema
23
Q

You should do a CT scan before lumbar puncture only if there are signs of…? [5]

A
  1. GCS 12
  2. CNS Signs
  3. Papilloedema
  4. Immunocompromised
  5. Seizure
24
Q

What should you give before doing CT scan in a patient with suspected meningitis? [1]

A

antibiotics

25
Q

Lumbar puncture is contraindacted if…? [7]

A
  1. Brain shift,
  2. Rapid GCS reduction,
  3. Resp/cardiac compromise,
  4. Severe sepsis,
  5. Rapidly evolving rash,
  6. Infection at LP site,
  7. Coagulopathy
    • (incl INR 2 1.5, Platelets < 40, DOAC, therapeutic LMWH)
    • Due to bleeding risk
26
Q

How should you interpret results of a lumbar puncture? (the basic principles) [6]

A
  • If white cell count is HIGH:
    • Neutrophilic → bacterial infection
    • Lymphocytic → usually viral infection
  • If the protein is HIGH:
    • Could be anything but more likely to be bacterial
  • If glucose is LOW (less than 50% of blood):
    • More likely to be bacterial
27
Q

How do you treat suspected meningitis? [4]

A
  1. ANTIBIOTICS MUST NOT BE DELAYED
  2. if suspected meningitis, treat for all major bacterial causes, i.e. meningococcus, pneumococcus and haemophilus influenzae (HI) using ceftriaxone (2x a day)
  3. if age ≥60, listeria suspected or immunocompromised, add amoxicillin
  4. if pneumococcus is suspected, add steroids
28
Q

How do you treat definitive meningitis caused by meningococcal infection and how long is the antibiotic therapy given for? [2]

A
  1. IV Ceftriaxone or Benzylpenicillin
  2. 5 days
29
Q

How do you treat definitive meningitis caused by pneumococcal infection and how long is the antibiotic therapy given for? [3]

A
  1. IV Ceftriaxone or Benzylpenicillin
  2. 10-14 days (Increase duration if complications)
30
Q

How do you treat definitive meningitis caused by listeria infection and how long is the antibiotic therapy given for? [2]

A
  1. IV Amoxicillin (stop Ceftriaxone)
  2. 21 days (Increase duration if complications)
31
Q

What are the presenting clinical features of viral encephalitis? [3]

A
  1. confusion
  2. fever
  3. +/- seizures
32
Q

What investigations should you order for a patient with suspected viral encephalitis? [4]

A
  1. Lymphocytic CSF (normal glucose)
  2. PCR
  3. EEG of Temporal lobe
  4. MRI
33
Q

What is an EEG (electroencephalogram)? [1]

A

test used to find problems related to electrical activity of the brain

34
Q

Which antibiotic is used to treat viral encephalitis and what does it target? [3]

A
  • aciclovir (used for…)
    • herpes simplex virus (HSV)
    • vesicular stomatitis virus (VSV)
35
Q

Intracerebral TB leads to lesions in which cranial nerves? [4]

A
  1. CN III
  2. CN IV
  3. CN VI
  4. CN IX
36
Q

HIV brain disease is a consequence of what? [1] and what conditions can it lead to? [8]

A
  • Consequence of unrecognised/untreated infection and marked immunodeficiency or lifestyle
  • can lead to:
    1. Encephalitis (ARVs)
    2. Dementia
    3. Neuro-syphilis (secondary or tertiary)
    4. Opportunistic
      • Tuberculosis,
      • Cryptococcus,
      • Toxoplasmosis
      • JCV- Progressive multi-focal leuco-encephalopathy
37
Q

What is progressive focal multifocal leuco-encephalopathy (PMLE)? [1]

A

neurological disorder characterized by destruction of cells that produce the myelin leading to progressive motor dysfunction

38
Q

Who is more susceptible to progressive focal multifocal leuco-encephalopathy (PMLE)? [4]

A
  • Immunocompromised patients
    1. HIV
    2. anti-TNF
    3. Transplant
39
Q

What is intracerebral toxoplasmosis? [1]

A

infection caused by the virus T. gondii in the CNS and mainly affects HIV infected patients, particularly in developing countries

40
Q

What are the typical presenting features of intracerebral toxoplasmosis? [3]

A
  1. Headache
  2. Seizures
  3. Focal CNS signs
41
Q

What kind of pathology does intracerebral toxoplasmosis cause in the brain? [1]

A

Multiple enhancing lesions in the basal ganglia

42
Q

How do you diagnose intracerebral toxoplasmosis? [2]

A
  1. Blood tests checking lgG and lgM
  2. PCR of CSF
43
Q

What drugs are used to treat intracerebral toxoplasmosis? [2]

A
  1. Sulphadiazine
  2. Pyramethamine

Week 7 - Clinical Microbiology & Infections 2 (16 decks)

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