Central Nervous System Flashcards
What is the CNS protected by?
- bone and membrane layers
brain is protected by the skull, spinal cord is protected by the vertebral column
If bacteria are crossing the BBB, they are likely to cause _____
encephalitis
If bacterial are crossing the CSF, they are likely to cause ____
meningitis
What are the three ways that microbes can cross the BBB?
- growing across, infecting the cells that compromise that barrier
- being passively transported across in intracellular vacuoles
- being carried across by infected white blood cells
What is the bodies response to being invaded in the CSF?
- and increase in lymphocytes and monocytes in the CSF
- a slight increase in protein also occurs, with the CSF remaining clear (this is termed aseptic meningitis)
- the response to pyogenic bacteria shows a more rapid increase in polymorphonuclear leukocytes and proteins, so that the CSF becomes visibly turbid (this is called septic meningitis)
____ meningitis is more severe but less common
Bacterial
What are the 3 key pathogens that are known to cause bacterial meningitis ? What do these three bacteria have in common?
- neisseria meningitidis and streptococcus pneumoniae
- haemophilis influenzae
- these three bacteria all possess a capsule, allowing them to be virulent
Neisseria meningitiditis is a gram ____ diplococci
negative
In meningococcal meningitis, the infection can be asymptomatic when the bacteria possess ____ and attach to the epithelium of the _____
pili
nasopharynx
About ___% of the population is a carrier of meningococcal meningitis, with higher carrier rates during epidemics
20
People that are possessing specific complement dependent bacterial ____ to capsular antigens are protected against invasion
antibodies
Individuals that have ____ complement deficiency are more susceptible to infection
C5-C9
Young children who have ______ and adolescents who have ______ are at the greatest risk of contracting meningococcal meningitis
- lost maternal Abs
- never encountered infecting serotypes
Person to person spread takes place via ______
droplet infection due to overcrowding and confinement (in prisons, college dorms, military barracks)
When in the year is the peak time for meningitis?
- winter/early spring - carrier rates here are between 60-80%
What is the incubation time for meningitis?
- 1-3 days
What are the symptoms of sudden onset meningitis?
- headache, sore throat, drowsiness, fever, stiff neck, hemorrhagic skin rash (indicates septicemia)
What is the mortality rates in treated meningitis individuals?
- treated is 10%
What serotypes do routine childhood vaccinations vaccinate for?
Serotypes A, C, Y and W135 (routine childhood vaccination)
What tests are used to diagnose meningitis?
- essentially a gram stain of CSF, culture or white blood cell counts
There are 6 different serotypes of _____, a-f, that are distinguishable serologically by their capsular polysaccharides
Haemophilus influenzae B
Haemophilus influenzae B leads to what disease?
- haemophilus meningitis
_______ is a resident of the respiratory tract of children. Maternal antibodies protect the child until they are about 3-4 months old, but then the antibodies wane and there is a _____ before the child develops their own antibodies
- H. influenzae B
- window of susceptibility
What is the incubation period of Haemophilus influenzae?
5-6 days
