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5. CP - Central Nervous System Infections > (27) Abscesses and other CNS infection > Flashcards

(27) Abscesses and other CNS infection Flashcards

1
Q

What are the different types of primary bacterial infections of the central nervous system?

A
  • meningitis
  • encephalitis
  • ventriculitis
  • brain abscess
  • ventriculoperitoneal shunt and external ventricular drain infection
  • subdural empyema
  • eye infections
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2
Q

What is a brain abscess?

A

A focal suppurative process within the brain parenchyma (pus in the substance of the brain)

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3
Q

Which bacteria cause brain abscesses?

A

Often mixed (polymicrobial)

  • streptococci (60-70%) eg. streptococcus milleri
  • staphylococcus aureus (10-15%)
  • anaerobes
  • gram negative enteric bacteria
  • others like fungi, mycobacterium tuberculosis, toxoplasma gondii, nocardia, actinomyces
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4
Q

When is the cause of brain abscess most commonly staphylococcus aureus?

A

After trauma/surgery

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5
Q

Give examples of gram negative enteric bacteria that may cause brain abscess

A
  • E. coli

- pseudomonas spp.

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6
Q

What are the 4 clinical settings that brain abscesses may develop in? (pathogenesis)

A
  • direct spread from “contagious” suppurative focus
  • haematogenous spread from a distant focus
  • trauma
  • cryptogenic
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7
Q

Brain abscesses might be caused by direct spread from contagious suppurative focus. Give examples

A

From ear (40%)

From sinuses, from teeth

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8
Q

Brain abscesses might be caused by haematogenous spread from a distant focus. Give examples

A
  • endocarditis

- bronchiectasis (often multiple abscessed)

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9
Q

Brain abscesses might be caused by trauma. Give examples

A
  • open cranial fracture

- post-neurosurgery

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10
Q

How many brain abscesses are cryptogenic (no focus, unknown cause)?

A

15-20%

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11
Q

What is the typical clinical presentation of brain abscess?

A
  • headache
  • focal neurological deficit
  • confusion
  • fever
  • nausea and vomiting
  • dizziness, seizures
  • neck stiffness
  • papilloedema
  • coma
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12
Q

What is the most common symptom of bran abscess?

A

Headache

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13
Q

How often is focal neurological deficit a symptom of brain abscess?

A

30-50% of patients

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14
Q

How often is fever a symptom of brain abscess?

A
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15
Q

Papillodema is a potential symptom of brain abscess. What is it?

A

Optic disc swelling that is caused by increased intracranial pressure. The swelling is usually bilateral and can occur over a period of hours to weeks.

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16
Q

What is the treatment of choice for brain abscess?

A

Drainage

small abscesses can be treated with antibiotics alone

17
Q

What are the purposes of drainage in brain abscesses?

A
  1. urgently reduce intracranial pressure
  2. confirm diagnosis
  3. obtain pus for microbiological investigation
  4. enhance efficacy of antibiotics
  5. avoid spread of infection into the ventricles
18
Q

Penetration of drugs into CSF and brain tissue differ. Which antibiotics achieve therapeutic concentrations in intracranial pus?

A
  • ampicillin
  • penicillin
  • cefuroxime
  • cefotaxime
  • ceftazidime
  • metronidazole
19
Q

Give an example of an empirical treatment regimen for sinugenic/odontogenic abscess

A

cefotaxime 2g 6-hourly +

metronidazole 500mg 8-hourly

Drained abscess: treat for 4-6 weeks

20
Q

Give and example of an empirical treatment regimen for otogenic abscess

A

benzyl penicllin 2.4g 6-hourly +

ceftazidime 2g 8-hourly

metronidazole 500mg 8-hourly

Drained abscess: treat for 4-6 weeks

21
Q

What are the complications associated with brain abscess?

A
  • raised intracranial pressure
  • mass effect
  • coning
  • rupture (usually into ventricles, causing ventriculitis)
22
Q

What is a subdural empyema?

A

Infection between dura and arachnoid mater

23
Q

What are the causes of subdural empyema?

A

Often polymicrobial

  • anaerobes
  • streptococci
  • aerobic gram negative bacilli
  • streptococcus pneumoniae
  • haemophilus influenzae
  • staphylococcus aureus
24
Q

Describe the possible pathogenesis in subdural empyema

A
  • spread of infection from sinuses (50-80%)
  • spread of infection from middle ear and mastoid (10-20%)
  • spread of infection from distant site (haematogenous) (5%)
  • following surgery or trauma
25
Q

What is the typical clinical presentation of subdural emyema?

A
  • headache
  • fever
  • focal neurological deficit
  • confusion
  • seizure
  • coma
26
Q

How is subdural empyema managed?

A
  • urgent surgical drainage of pus

- antimicrobial agents

27
Q

What should guide antibiotic therapy in subdural empyema?

A

Culture of pus

28
Q

What are ventriculoperitoneal (VP) shunts and external ventricular drains? (EVD)

A

Devices that neurosurgical patents may have inserted into the ventricles to monitor intracranial pressure or drain excess CSF

29
Q

What are the risks with EVDs and VP shunts?

A

They can become colonised with organisms that subsequently cause ventriculitis

30
Q

How would you diagnose EVD and VP shunt infection?

A

CSF microscopy and culture

31
Q

Which bacteria is the most common cause of EVD and VP shunt infection?

A

Coagulase-negative staphylococci

32
Q

How are EVD and VP shunts treated?

A
  • device removal

- intraventricular antibiotics

5. CP - Central Nervous System Infections (3 decks)

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