CNS Infections Flashcards
RFs of bacterial CNS infections
non-intact BBB, very young, elderly, immunocomp
Ways in which bacterial infections spread to CNS?
- hematogenously (most common)
- bone (where thin like mastoiditis, sinusitis, middle ear infx, abscessed tooth)
- interconnecting veins (central facial infections)
- axonal spread
Who is most likely to get bacterial meningitis?
groups of young adults living in crowded conditions
infants
Bacterial meningitis is an infection of ______, _____, and _______ by bacterial.
arachnoid, subarachnoid space, and CSF
Organisms that cause bacterial meningitis?
infants: E. coli, beta-hemolytic strep
children/adults: step pneumo (blood), Neisseria (UTI), H flu (ear infection)
Common symptoms of bacterial meningitis?
fever, severe HA, stiff neck
Positive PE tests in bacterial meningitis
Kernig’s (flex hip/knee)
Brudzinski’s (flex neck)
CSF analysis of bacterial meningitis
- neutrophils with high WBC count
- high proteins
- low glucose
- Gram stain
Bacterial meningitis tx
IMMEDIATE broad spectrum abx
vaccine: Neisseria meningitides and H-flu
Etiology of epidural abscess
- infection in neighboring areas resulting in osteomyelitis or TB of vertebral column
- infection post surgery (staph)
Etiology of subdural abscess
- Infection spread via sinuses or middle ear to subdural space
- staph aureus or strep
Progression of subdural abscess
spinal empyema -> compression of spinal cord -> paralysis/death
Etiology of brain abscess
- extension from sinusitis, otitis, or meningitis
- hematogenous spread
Treatment of epidural, subdural, and brain abscesses
Surgical evacuation and IV abx
Dx imaging of choice for epidural, subdural, and brain abscesses
CT scan
2 types of CNS spirochete infections
Syphilis and Lyme Disease
What organism causes Lyme Disease?
Borrella Burgdoferi in ticks
Signs of syphilis CNS infection
Tabes dorsalis = inflamm/degen of posterior columns; impairs proprioception/vibration; causes shooting pain in legs and Robertson pupil paresthesias
General paresis of the insane = encephalitis due to spirochete invasion of brain; mental and personality changes
How are viral infections of CNS spread?
blood and peripheral nerves
Etiology of viral meningitis?
unidentified virus; possibly enterovirus, HIV, chicken pox, herpes
Possible drug-induced
CSF results of viral meningitis
high cell count
pleocytosis
high protein
normal glucose
How is viral meningitis different from bacterial?
- aseptic/viral has NO neuro deficits
- viral has normal glucose; bacterial is low
- bacterial organism can be identified via Gram stain
definition of encephalitis
infection/inflamm of CNS neurons and glial cells
Etiology of viral encephalitis
- Generalized viral infection (pneumonia, enteritis)
- Primary CNS infection (rabies, West Nile)
viral encephalitis management
acute and convalescent titers to measure antibodies
What are 3 different types of viral encephalitis and what bug causes them?
Herpes Simplex (HSV I and II)
Cytomegalovirus (CMV)
HIV
Who is affected by Herpes Simplex Encephalitis
HSV I: 2-3 yo
HSV II: neonates during vaginal delivery (not with C-section)
What diseases can HIV cause in the CNS?
encephalitis, aseptic meningitis, AIDS-related dementia
Which encephalitis is transmitted to fetus transplacentally?
cytomegalovirus encephalitis
How is herpes simplex encephalitis treated?
Acyclovir
How does the HSV I and II virus get to brain?
via the trigeminal ganglion
What happens if HSV encephalitis gets into frontal/temporal lobes?
personality changes, bizarre behaviors, anosomia, dementia, gustatory (taste) hallucinations
How is HSV encephalitis detected in CSF?
PCR
Examples of arthropod borne CNS viruses
St. Louis encephalitis, Equine encephalitis, West Nile, tick-bourne encephalitis
prion
abnormal form of neuron glycoprotein that is resistant to protease breakdown
Examples of prion diseases
Creutzfeldt Jakob Disease (CJD): disease of humans and animals; gene mutation alters amino acid sequence (familial/sporadic) or iatrogenic (variant)
Kuru: Papua New Guinea tribe that ate dead people’s brains
Mad Cow disease: consumption of infected beef
Scrapie: prion disease in sheep
Signs of prion disease
personality changes, mental changes, dementia, hallucinations, gait abnormalities
MRI findings of prion disease
“spongey encephalopathy” from neuron loss and gliosis
Prion disease tx
supportive therapy
Fungi that can infect CNS
Candida, Aspergillus, Cryptococcus, Mucormycosis
Mycobacteria that can infect CNS
TB
Amoebic CNS infection from what?
Naegleria floweri in freshwater or hot springs
blood in CSF =
intracranial bleed (i.e. subarachnoid hemorrhage)
monocytes in CSF =
encephalitis (fungal or viral)
elevated PMN in CSF =
bacterial meningitis
low glucose in CSF =
bacterial or fungal/TB infection
+G stain in CSF =
bacterial
