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YEAR 5: Microbiology and Infection > MI: CNS Infections and Meningitis Pt.2 > Flashcards

MI: CNS Infections and Meningitis Pt.2 Flashcards

1
Q

Which bacterium is associated with causing encephalitis?

A

Listeria monocytogenes

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2
Q

Name two types of amoeba that cause encephalitis.

A
  • Naegleria fowleri
  • Acanthamoeba species and Balamuthia mandrillaris

NOTE: these amoebae spread by direct extension (e.g. through the cribiform plates)
up your nose - swimming in the baths of bath
still, stagnant water

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3
Q

What is toxoplasmosis and how is it spread?

A
  • Obligate intracellular parasite
  • Spread via oral, transplacental or organ transplant route
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4
Q

How do bacteria that cause brain abscesses tend to spread?

A

Direct extension
(e.g. from otitis media, mastoiditis or paranasal sinuses)

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5
Q

List some organisms that can cause brain abscesses.

A
  • Staphylococci
  • Streptococci
  • Gram-negative organisms (mainly in neonates)
  • TB
  • Actinomyces and Nocardia species
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6
Q

Name a common spinal infection.

A

Pyogenic vertebral osteomyelitis

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7
Q

How can pyogenic vertebral osteomyelitis spread?

A

Direct open spinal trauma from infections in adjacent structures

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8
Q

What are some long-term consequences of pyogenic vertebral osteomyelitis?

A
  • Permanent neurologic defects
  • Significant spinal deformity
  • Death
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9
Q

List some risk factors for pyogenic vertebral osteomyelitis.

A
  • Age
  • IVDU - staph aureus
  • Long-term systemic steroids
  • Diabetes mellitus
  • Organ transplantation
  • Cancer
  • Malnutrition
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10
Q

Compare the use of MRI and CT in CNS infections.

A

MRI is better than CT at detecting parenchymal abnormalities such as abscesses and infarctions

CT can be useful for looking at raised ICP

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11
Q

List some other useful tests for suspected meningitis.

A
  • Blood culture - typical
  • Blood PCR - aseptic
  • Throat swab - Meningococus, Strep. Pneumo

Strep Pneumo (1in5) and Meningococcus (1in20) carried in nasopharynx

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12
Q

What studies can be done with CSF?

A
  • Colour/clarity
  • Cell counts
  • Chemistry (protein and glucose)
  • Stains (Gram, auramine, Inda Ink etc.)
  • Cultures
  • PCR
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13
Q

Describe the typical CSF analysis results of:

  1. Bacterial meningitis
  2. Aseptic meningitis
  3. Tuberculous meningitis
A

Bacterial meningitis:

  • Turbid
  • High polymorphs
  • High protein
  • Low glucose

Aseptic meningitis:

  • Clear
  • High lymphocytes
  • High protein
  • Normal glucose

Tuberculous meningitis:

  • Clear
  • High lymphocytes
  • High protein
  • Low glucose

Abnormal WCC in CSF >5

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14
Q

Describe the Gram-stain and microscopic appearance of:

  1. S. pneumonia
  2. N.meningitidis
  3. L. monocytogenes
  4. TB
  5. Cryptococcus
A
  1. S. pneumonia = Gram-positive alpha-haemolytic diplococci
  2. N.meningitidis = Gram-negative non-haemolytic diplococci
  3. L. monocytogenes = Gram-positive rods
  4. TB = Stains positively with Ziehl-Neelsen (red and blue)
  5. Cryptococcus = Stains positively with India Ink (appears like an orbit - yeast in the middle with a capsule around the outside)
    Does not gram stain
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15
Q

What is another key clinical feature of Cryptococcal meningitis?

A

High opening pressure

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16
Q

List some limitations of diagnositcs in menigitis.

A
  • MRI oedema pattern may not differentiate between tumour or stroke or vasculitis in some patients
  • Serology may not be useful in the early stages of infection
  • Difficulties obtaining CSF
  • PCR techniques are expensive
17
Q

What is the generic therapy used in meningitis?

A
  • Ceftriaxone 2g IV BD
  • If > 50 years or immunocompromised = amoxicillin 2 g IV 4 hourly

NOTE: this is because ceftriaxone does NOT cover Listeria

18
Q

What it the generic therapy used in meningo-encephalitis?

A
  • Aciclovir 10 mg/kg IV TDS
  • Ceftriazone 2 g IV BD
  • If > 50 years or immunocompromised = amoxicillin 2 g IV 4 hourly
19
Q

Name the specific therapy for meningitis caused by:

  1. S. pneumoniae
  2. N. meningitidis
  3. H. influenzae
  4. Group B Streptococcus
  5. Listeria
  6. Gram-negative bacilli
  7. Pseudomonas
A

1. S. pneumoniae = Ceftriaxone

2. N. meningitidis = Ceftriazone 4 g/day

3. H. influenzae = Cefotaxime 12 g/day

4. Group B Streptococcus = Pen G 18-24 mu/day

5. Listeria = Ampicillin 12 g/day

6. Gram-negative bacilli = Cefotaxime 12 g/day

7. Pseudomonas = Meropenem 6 g/day

YEAR 5: Microbiology and Infection (47 decks)

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