Brain abscesses and other infections of the central nervous system Flashcards Preview

Clinical Pathology > Brain abscesses and other infections of the central nervous system > Flashcards

Flashcards in Brain abscesses and other infections of the central nervous system Deck (19)
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1
Q

What are the different types of primary bacterial infections of the CNS?

A
  • Meningitis
  • Encephalitis
  • Ventriculitis
  • Brain Abscess
  • Ventriculoperitoneal shunt and external ventricular drain infection
  • subdural empyema
  • (eye infections)
2
Q

What is a brain abscess?

A

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

3
Q

What is the aetiology of brain abscesses?

A
  • Often mixed (polymicrobial) - usually need broad spectrum Abx
  • Streptococci (60-70%) e.g. Streptococcus “milleri”
  • S. aureus (10-15%) most common after trauma/surgery
  • Anaerobes - usually piggyback on other bacteria
  • Gram negative enteric bacteria (E.coli, Pseudomonas spp.)
  • Others e.g. fungi, Mycobacterium tuberculosis, - Toxoplasma gondii, Nocardia, Actinomyces
4
Q

What is the pathogenesis of brain abcesses?

A
  • Direct spread from “contiguous” suppurative focus (e.g. from middle ear[40%], sinuses, teeth)
  • Haematogenous spread from a distant focus e.g. endocarditis, bronchiectasis (often multiple abscesses)
  • Trauma (e.g., open cranial fracture, post-neurosurgery)
  • Cryptogenic (no focus ~15-20%).
5
Q

What is the clinical presentation of brain abcesses?

A
  • Headache (most common)
  • Focal neurological deficit (30-50%)
  • Confusion
  • Fever (
6
Q

Why is drainage the treatment of choice for brain abscesses?

A
  1. to urgently reduce intracranial pressure
  2. to confirm diagnosis
  3. to obtain pus for microbiological investigation
  4. to enhance efficacy of antibiotics
  5. to avoid spread of infection into the ventricles
7
Q

What Abx treatment is given for brain abscesses and why?

A
  • Physiological properties of blood-brain barrier and blood CSF-barrier are distinct
  • Penetration of drugs into CSF and brain tissue differ
  • Ampicillin, penicillin, cefuroxime, cefotaxime, ceftazidime, and metronidazole achieve therapeutic concentrations in intracranial pus
8
Q

What is the treatment regimen for a sinugenic/odontogenic abscess?

A

iv cefotaxime 2g 6-hourly +

iv metronidazole 500mg 8-hourly

9
Q

What is the treatment regimen for an otogenic abscess?

A

iv benzyl penicillin 2.4g 6-hourly +
iv ceftazidime 2g 8-hourly +
iv metronidazole 500mg 8-hourly

10
Q

What are the complications of brain abscesses?

A
  • Raised intracranial pressure, mass effect, coning

- Rupture (usually into ventricles) causing ventriculitis

11
Q

What is subdural empyema?

A

Infection between dura and arachnoid mater.

12
Q

What is the aetiology of subdural empyema?

A

(often polymicrobial) anaerobes, streptococci, aerobic Gram negative bacilli, Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus

13
Q

What is the pathogenesis of subdural empyema?

A
Pathogenesis: 
- spread of infection from sinuses (50-80%) 
- middle ear and mastoid (10-20%)
distant site (5%, haematogenous) 
- following surgery or trauma
14
Q

Which of the 3rd generation cephalosporins is one of the few antibiotics active against P. aeruginosa? (common cause of ear infections)

A

Ceftazidime

15
Q

What is the clinical presentation of subdural empyema?

A

Headache fever, focal neurological deficit, confusion, seizure, coma

16
Q

What is the treatment for subdural empyema?

A

Urgent surgical drainage of pus, antimicrobial agents

17
Q

What is the aetiology of ventriculitis?

A

EVDs and VP shunts can become colonised with organisms that subsequently cause ventriculitis

18
Q

What is the most common cause of ventriculitis due to EVD/VP colonisation?

A

Coagulase-negative staphylococci

19
Q

What is the treatment for ventriculitis?

A

Device removal, intraventricular antibiotics

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