Week 10 - Topic 3: CNS Infections Flashcards
What are the 3 tissue layers covering the CNS?
Meninges
1) Pia mater
2) Arachnoid mater
3) Dura mater
What does the CNS bathe in?
CSF - cerebral spinal fluid
What is between the dura mater and the skull?
Epidural space
What is between the arachnoid and dura mater?
Subdural space
What is between the pia and arachnoid mater?
Subarachnoid space
In which space is the CSF located?
Subarachnoid space and in ventricles
Where is CSF produced?
Choroid plexus in the ventricles
roof of 3rd and 4th ventricle and floor of lateral ventricle
What is the purpose of CSF?
Communication of neurons and cushion in case of trauma
True or False: CSF is normally sterile.
True
Why are epithelial cells lining the brain’s blood vessels less permeable than blood vessels in the body?
Tight junctions = blood brain barrier
What substances does the blood brain barrier limit access to the brain?
- Invading microorganisms
- Toxic substances
- Ig
- Complements
- Abx
Your patient has meningitis. What must you consider with regards to antibiotics dosage?
Give them maximal or “meningitis” doses to cross over to the CNS (not doses systemically)
What are the pathways of entry for CNS infections (5) and what microorganisms are associated with each?
1) Olfactory nerve pathway (influenza, herpes simplex, polio, rabies, west nile, etc.)
2) Hematogenous pathway (arthropod borne tropical viruses like Zika)
3) Intestinal tract (polio)
4) Respiratory tract (Neisseira meningitis, Strep Group A, Haemophilus influenza type B)
5) Peripheral nerve pathway (Chicken pox, herpes simplex)
How can one be infected with CJD prion?
Coming into contact with human brain products, dural grafts, corneal grafts, human growth hormone
What are portals of entry for local CNS invasion?
Ears, sinuses, spine injury/defects, trauma
What causes spongiform encephalopathy?
Prion diseases
What does the brain damage from spongiform encephalopathy look like?
Brain looks like a sponge due to the vacuoles
What is CSF collected in during a lumbar puncture?
Multiple sterile, screw cap containers
True or False: If you do the aseptic sterile no touch technique, you can send the initial volume for gram stain, cell count and cultures.
False, send tube #3 or #4 bc the first tube will most likely be contaminated with skin flora.
True or False: You use face shields during CSF culture.
False
But you use mask, sterile gloves, gowns and sterile field
True or False: You can refrigerate CSF cultures.
False, send it to lab ASAP
True or False: Physicians must start meningitis treatment before culture results.
True, bc meningitis can cause rapid irreversible damage
Why must we proceed with caution when we evaluate PTs with meningitis?
Clinical findings do not reliably differentiate bacteria from other causes (ex: viruses)
Particularly true for pediatrics
What is the difference between septic and aseptic meningitis.
Septic caused by bacteria/brain abscesses, turbid CSF, high protein/neutrophil count, low glucose
Aseptic caused by viruses /TB/fungi, cells are mainly mononuclear, moderate-high protein count, normal glucose
What is encephalitis?
Inflammation of cerebral cortex