Flashcards in Infections Deck (39):
1
Potential spaces in the brain that can be infected
Epidural
Subdural
Subarachnoid
Intraparenchymal
Draining veins/sinuses
2
Abscess
epidural infection (enclosed)
tend to be ocal
can present like tumours
could be due to osteomylitis
3
Empyema
subdural infection
can spread
mass effect, push brain over
4
Meningitis
subarachnoid
5
Encephalitis
diffuse parenchymal infection
6
Brain abscess
parenchymall focal infection
like a brain tumour
7
Septic thrombophlebitis
infected venous clot
8
Hematogenous sources
most agents
9
Contiguous sources
sinus/ear/face
bacterial
10
Direct inoculation
trauma/surgery
bacterial
11
Nervous sources
HSV
VZV
12
CSF studies
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
13
Bacterial meningitis
Life-threatening
change in LOC
14
Bacterial meningitis CSF
+++ WBC
+++ PMN
low glucose
15
Viral meningitis
self-limiting
no change in LOC
16
Meningitis presentation
fever, headache, stiff neck
usually CT --> lumbar puncture
but imaging usually normal
17
viral meningitis CSF
+/- WBC
+ lymphocytes
normal gluc
do PCR for HSV, enterovirus, etc
18
Fungal meningitis CSF
+/- WBC
+ lymphocytes
normal gluc
19
Bacterial meningitis pathogens
Newborn: GBS, E coli, Listeria
Infant: GBS, E coli, Hemophilius
Adult: pneumococcus, meningococcus, haemophilus, listeria, staph
20
Pathogenesis of meningitis
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
Pia-arachnoiditis SSx
headache
stiff neck
Kernig/Brudzinski signs
22
Subpial encephalopathy ssx
confusion
stupor
coma
convulsions
23
Inflammatory/vascular involvement of CN roots SSx
ocular palsies
facial weakness
deafness
24
Thrombosis of meningeal veins SSx
focal seizures/cerebral defects
e.g. hemiparesis, aphasia
may be a spinal cord infarction
25
Cerebellar/cerebral hemisphere herniation SSx
upper cervical cord comrpession with quadriplegia or
signs of midbrain-third nerve compression
26
Meningitis tx principles
start appropriate abx ASAP
if LP is delayed due to need for CT, obtain blood cultures + start Abx immediately
27
Meningitis empiric therapy
Ceftriaxons 2g iv q12h
+ vancomycin (for penicillin-resistant S pneumoniae)
+/- ampicilin (elderly, immunosuppressed, pregnant)
+/- dexamethasone (prior to/with first dose of Abx)
28
Viral meningitis etiology
enteroviruses - echo/coxsackie
HSV, varicella, HIV, mumps
HSV - medical emergency
consider encephalitis if altered LOC
lymphocytic choriomeningitis
adeno
CMV
29
Bacterial brain abscess causes
trauma
emboli
osteomyelitis
30
Parasitic/fungal brain abscess
in immunocompromised
31
Immunocompetent brain abscess agents
Parasitic: toxoplasma gondii
Fungal: cryptococcus neoformans
Mycobacterial: TB
Polymicrobial bacterial infection:
- strep anginosus
- anaerobes
- staph aureus
- gram negative
32
Symptoms of brain abscess
headache
fever
focal neurological deficits
mental status changes
seizures
N/V
nuchal rigidity
symptoms not acute as meningitis
33
Brain abscess tx
aspiration
empiric antibiotics:
ceftriaxone + metronidazole +/- vanco
OR meropenem +/0 vancomycin
GCs for swelling (dexamethasone)
34
Subdural empyema overview
Bacterial: S aureus
usually due to trauma/surgery/sinus disease
tx with drainage/antibiotics
35
Encephalitis SSx
acute fever
convulsions, delirium, confusion, stupor/coma
aphasia, hemiparesis
involuntary movements, ataxia
myoclonic jerks, nystagmus
could have a meningitis component
36
Meningitis vs encephalitis
Meningitis: intact brain fxn
Encephalitis: abnormal brain fxn - altered mental status, motor/sens deficits, change in behaviour/personality, speech/movement disorder
37
Viral causes of encephalitis
HSV, varicella, EBV
WEE, EEE, West Nile
HIV
Rabies
viral infections cross BBB
38
Other causes of encephalitis
CJD - spongiform encephalopathy
- usually presents more as a dementia rather than acute infection
Prion disease
39