Infections Flashcards

1
Q

Potential spaces in the brain that can be infected

A
Epidural
Subdural
Subarachnoid
Intraparenchymal
Draining veins/sinuses
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2
Q

Abscess

A

epidural infection (enclosed)
tend to be ocal
can present like tumours
could be due to osteomylitis

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3
Q

Empyema

A

subdural infection
can spread
mass effect, push brain over

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4
Q

Meningitis

A

subarachnoid

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5
Q

Encephalitis

A

diffuse parenchymal infection

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6
Q

Brain abscess

A

parenchymall focal infection

like a brain tumour

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7
Q

Septic thrombophlebitis

A

infected venous clot

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8
Q

Hematogenous sources

A

most agents

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9
Q

Contiguous sources

A

sinus/ear/face

bacterial

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10
Q

Direct inoculation

A

trauma/surgery

bacterial

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11
Q

Nervous sources

A

HSV

VZV

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12
Q

CSF studies

A

increased protein: may mean inflammation causing leaky blood vessels
high gluc: usually diabetes
low gluc: fungal/TB
Electrophoresis for protein peaks to identify unusual infections

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13
Q

Bacterial meningitis

A

Life-threatening

change in LOC

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14
Q

Bacterial meningitis CSF

A

+++ WBC
+++ PMN
low glucose

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15
Q

Viral meningitis

A

self-limiting

no change in LOC

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16
Q

Meningitis presentation

A

fever, headache, stiff neck
usually CT –> lumbar puncture
but imaging usually normal

17
Q

viral meningitis CSF

A

+/- WBC
+ lymphocytes
normal gluc
do PCR for HSV, enterovirus, etc

18
Q

Fungal meningitis CSF

A

+/- WBC
+ lymphocytes
normal gluc

19
Q

Bacterial meningitis pathogens

A

Newborn: GBS, E coli, Listeria
Infant: GBS, E coli, Hemophilius
Adult: pneumococcus, meningococcus, haemophilus, listeria, staph

20
Q

Pathogenesis of meningitis

A

1) Nasopharyngeal colonization
2) Local invasion
3) bacteremia
4) endothelial cell injury –> increased BBB permeability
5) meningeal invasion
6) subarachnoid space inflammation –> increased BBB permeability, cerebral vasculitis, cytotoxic edema, cerebral infarction
7) increased CSF outflow resistance
8) hydrocephalus/interstitial edema
9) increased ICN
10) decreased cerebral blood flow

21
Q

Pia-arachnoiditis SSx

A

headache
stiff neck
Kernig/Brudzinski signs

22
Q

Subpial encephalopathy ssx

A

confusion
stupor
coma
convulsions

23
Q

Inflammatory/vascular involvement of CN roots SSx

A

ocular palsies
facial weakness
deafness

24
Q

Thrombosis of meningeal veins SSx

A

focal seizures/cerebral defects
e.g. hemiparesis, aphasia
may be a spinal cord infarction

25
Q

Cerebellar/cerebral hemisphere herniation SSx

A

upper cervical cord comrpession with quadriplegia or

signs of midbrain-third nerve compression

26
Q

Meningitis tx principles

A

start appropriate abx ASAP

if LP is delayed due to need for CT, obtain blood cultures + start Abx immediately

27
Q

Meningitis empiric therapy

A

Ceftriaxons 2g iv q12h
+ vancomycin (for penicillin-resistant S pneumoniae)
+/- ampicilin (elderly, immunosuppressed, pregnant)
+/- dexamethasone (prior to/with first dose of Abx)

28
Q

Viral meningitis etiology

A
enteroviruses - echo/coxsackie
HSV, varicella, HIV, mumps
HSV - medical emergency
consider encephalitis if altered LOC
lymphocytic choriomeningitis
adeno
CMV
29
Q

Bacterial brain abscess causes

A

trauma
emboli
osteomyelitis

30
Q

Parasitic/fungal brain abscess

A

in immunocompromised

31
Q

Immunocompetent brain abscess agents

A
Parasitic: toxoplasma gondii
Fungal: cryptococcus neoformans
Mycobacterial: TB
Polymicrobial bacterial infection:
- strep anginosus
- anaerobes
- staph aureus
- gram negative
32
Q

Symptoms of brain abscess

A
headache
fever
focal neurological deficits
mental status changes
seizures
N/V
nuchal rigidity

symptoms not acute as meningitis

33
Q

Brain abscess tx

A
aspiration
empiric antibiotics:
ceftriaxone + metronidazole +/- vanco
OR meropenem +/0 vancomycin
GCs for swelling (dexamethasone)
34
Q

Subdural empyema overview

A

Bacterial: S aureus
usually due to trauma/surgery/sinus disease
tx with drainage/antibiotics

35
Q

Encephalitis SSx

A
acute fever
convulsions, delirium, confusion, stupor/coma
aphasia, hemiparesis
involuntary movements, ataxia
myoclonic jerks, nystagmus
could have a meningitis component
36
Q

Meningitis vs encephalitis

A

Meningitis: intact brain fxn
Encephalitis: abnormal brain fxn - altered mental status, motor/sens deficits, change in behaviour/personality, speech/movement disorder

37
Q

Viral causes of encephalitis

A
HSV, varicella, EBV
WEE, EEE, West Nile
HIV
Rabies
viral infections cross BBB
38
Q

Other causes of encephalitis

A

CJD - spongiform encephalopathy
- usually presents more as a dementia rather than acute infection

Prion disease

39
Q

Septic thrombophlebitis overview

A

bacterial - trauma, surgery, facial infection, sinusitis

Symptoms: headache, obtundation, seizures, venous infarctions