Nervous system microbiology Flashcards
What is aseptic meningitis?
Non-bacterial meningitis
What are the 3 most common bacterial agents in meningitis?
Nieseria meningiditis, streptococcus pneumoniae, haemophilus influenzae B
Why are meningococcus, pneumococcus and HiB the most common causes of meningitis?
They are encapsulated => can’t be opsonised => can’t be phagocytosed => evade CNS defences
What are the most specific signs of meningitis in adults?
Stiff neck, photophobia, mental status changes and seizures
What are 7 signs of meningitis in kids?
Fever, N/V, altered MS, bulging fontanel, irritability and reduced feeding
What is the only way to definitively Dx meningitis
Isolation of organism from CSF
What is a normal ICP?
<150mm H2O
What is a normal level of protein in CSF?
<0.4g/L
What are the typical changes in CSF of bacterial meningitis?
Turbid appearance, Positive gram stain, Protein high (>1g/L), Many white cells (thousands of neutrophils), Low glucose (<40% of blood)
What is a normal level of glucose in CSF?
> 60% of blood levels
What is the treatment for bacterial meningitis in adults?
3rd generation cephalosporin
Which drug is used to treat herpes simplex viral encephalitis?
Aciclovir
What impairment of consciousness is there in meningitis?
None because brain should not be affected
What can a neurotropic virus do?
Can replicate inside nerve cells
What can a neuroinvasive virus do?
Enter or infect the CNS
What can a neurovirulent virus do?
Cause nervous system disease
What is myelitis?
Infection of the spinal cord
Which cells do not express type 1 MHC?
Neurons
Why are viruses in the CNS safer?
Because neurons do not express Type 1 MHC, thus they are safe from cytotoxic T cells
Where do viruses replicate in the nervous system?
In the cell bodies of neurons
When can lymphocytes enter the CNS?
When there is inflammation and disruption of the BBB
What is the only virus you can vaccinate for after the infection and still save your life?
Rabies
How is rabies transmitted?
Injection of infected saliva through biting
Which virus causes cold sores?
Herpes simplex 1
Which virus causes genital herpes?
Herpes simplex 2
Which virus causes shingles?
Varicella-zoster virus
Which cells does polio virus typically damage?
Alpha motoneurones in the ventral horn
