0903 CNS infections Flashcards
What features form the continuous barrier between blood and brain of the BBB?
Intercellular tight junctions (limit paracellular flux); limited pinocytotic activity (limit transcellular flux); addition physical protection of basement membrane and astrocyte foot processes.
What is the normal CSF volume in adults?
100-160mLs.
Define myelitis.
Inflammation of the spinal cord.
Define encephalitis.
Inflammation of the brain.
Define meningitis.
Inflammation of the meninges
Contrast Extradural; to epidural.
Both indicate a disorder occurring outside the dura mater, but epidural refers to this still being in the spinal canal.
What are the main routes of spread as a mechanism of CNS infection?
Physical pathway (trauma, post surgical), haematogenous pathway. Less common are peripheral nerve or olfactory nerve pathways.
What are the cardinal signs of meningitis?
headache, fever, neck stiffness, photophobia. May also, depending on cause, show rash, pneumonia, sinusitis etc.
Kernig’s or Brudzinski sign positive.
What is the gram stain and morphology of Streptococcus pneumonia?
gram positive diplococcus.
What is the gram stain and morphology of Neisseria meningitides?
gram negative diplococcus.
What is the gram stain and morphology of Listeria monocytogenes?
gram positive bacillus.
What is the gram stain and morphology of Group B streptococcus?
Gram positive coccus in chains.
What would be the most likely infectious agent behind meningitis with an associated rash?
Neisseria meningitidis
What would be the most likely infectious agent behind meningitis with an associated upper or lower respiratory tract infection?
Streptococcus pneumonia
List some viruses that can cause an encephalitis/myelitis.
Herpes simplex, enterovirus, varicella zoster, cytomegalovirus, HIV, arboviruses, rabies/Hendra/lyssavirus
