CNS Infections I Flashcards

1
Q

clinical features of CNS infection

A

Fever, headache, altered mental status, or focal neurologic deficits

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2
Q

what are the routes of infections for CNS infections

A
  • Hematogenous dissemination
  • direct injury
  • neural tissue (rare)
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3
Q

what is trojan horse

A

it is a method of microbes to spread through the blood where they infect WBCs then the WBC squeeze through the barrier to get into the cell

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4
Q

what is encephalitis and myelitis

A

encephalitis - inflammation of brain parenchyma

myelitis - infection of spinal cord

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5
Q

what are abscesses

A

localized infection in the brain or spinal cord

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6
Q

universal epidemiological considerations

A

age, season, geography, medical condition/underlying disease

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7
Q

how do you diagnose CNS infection

A

lumbar puncture and neuroimaging like CT or MRI (done before lumbar puncture)

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8
Q

what are some risks to doing a lumbar puncture

A
  • headaches
  • infection
  • temporary pain or numbness to legs or lower back pain
  • risk of bleeding into spinal canal
  • ICP could be due to cerebral mass lesion and lumbar puncture –> brain herniation
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9
Q

normal pressure in the CSF

A

70-180mm H2O

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10
Q

how is a lumbar puncture performed

A

CSF is drawn from between two vertebrae with patient in the lateral decubitus position

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11
Q

appearance of normal and abnormal CSF

A

normal - clear, colorless

abnormal - cloudy/turbid

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12
Q

what are routine tests for CSF

A

WBC count with differential, RBC count, [Glucose], [protein], gram stain, bacteria culture

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13
Q

normal CSF value for WBC, RBC, glucose, protein

A

WBC - 0-5/mm3 for children and adults then 32/mm3 for neonates
RBC - none
glucose - 40-70mg/dL
protein: newborn is 150mg/dL and then from 6 months on it is 18-58mg/dL

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14
Q

typical findings in meningitis for bacteria: pressure, WBC count, cell differential, protein, glucose

A
pressure elevated
WBC:  greater than 1000/mm3
mainly neutrophils
protein 100-500mg/dL
glucose 0-10mg/dL
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15
Q

typical findings in meningitis for viral: pressure, WBC count, cell differential, protein, glucose

A
normal pressure
WBC:  less than 100/mm3
mainly lymphocytes
protein 50-100mg/dL
glucose 40-70mg/dL
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16
Q

typical findings in meningitis for fungal: pressure, WBC count, cell differential, protein, glucose

A
variable pressure
variable WBC
lymphocytes (and PMNs)
protein 50-100mg/dL
glucose less than 40mg/dL
17
Q

typical findings in meningitis for tuberculosis: pressure, WBC count, cell differential, protein, glucose

A
variable pressure
variable WBC
lymphocytes
protein 10-500mg/dL
glucose 20-40mg/dL
18
Q

clinical features of acute meningitis

A
  • Onset: hours-several days
  • Life-threatening
  • Meningism: Fever, Headache, Nuchal rigidity, Nausea & Vomiting, Photophobia
  • Altered mental status
19
Q

features of aseptic meningitis

A

– Increased lymphocytes
– Self limiting
– Viral or non infectious (Absence of cultivable bacteria or fungi)

20
Q

features of chronic meningitis

A

–rare
– Slow onset (period of weeks)
– ↓ Fever, lethargy
– TB, Fungi & (Protozoa)

21
Q

tests for meningism

A
  • Inability to flex neck (chin to chest)
  • Inability to oppose nose with knee
  • Tripod sign: Inability to sit up without using hands
  • Kernig’s sign: inability to fully straighten leg when in laying position and leg is pulled up
  • Brudzinski’s sign: child is flat on back and when neck pulled up, knees come up too
22
Q

bacterial causes of meningitis in neonates and infants

A

neonates: S. agalactiae (group B strep) and E. coli, L. monocytogenes
infants: S. pneumonia (N. meningitides and H. influenza)

23
Q

bacterial causes of meningitis in adolescents and adults

A

adolescents: S. pneumonia (N. meningitides and H. influenza)
adults: N. meningitides, S. pneumonia

24
Q

bacterial causes of meningitis in adults greater than 50 years old

A

S. pneumonia (N. meningitides, L. monocytogenes and gram negs)

25
Q

most frequently observed in children and adults with meningitis

A

Strep pneumonia

26
Q

where is strep pneumonia found in the human body

A

throat and nasopharynx

27
Q

strep pneumonia is associated with what conditions

A

previous pneumonia infections, otitis media, mastoiditis, sinusitus, endocarditis

28
Q

basilar skull fracture and CSF leak is associated with what bacteria in association with bacterial meningitis

A

Strep pneumonia

29
Q

what type of bacteria is strep pneumonia? where does it get its virulence?

A

gram positive diplococci

virulence from capsule, pneumolysin, IgA protease

30
Q

clinical features of strep pnuemonia

A

rapid 1-2 days

impaired consciousness common

31
Q

neisseria meningitides is most common in who

A

children and young adults

32
Q

biological features of neisseria meningitides

A
  • non motile gram neg diplococci (kidney bean shaped)
  • 6 serotypes cause epidemics - A, B, C, W, X, Y
  • higher in military recruit camps and schools
  • fastidious and like high CO2 and must be grown on chocolate agar or martin-thayer agar
33
Q

where does neisseria meningitides gets virulence factor from

A

capsule (serotype A, B, C, W-135, X, Y)
IgA protease
pili
LOS (lipooligosaccharide)

34
Q

clinical features of neisseria meningitides

A

quick onset
acute photophobia
skin petechiae → ecchymoses/diffuse petechial rash - DIC

35
Q

what test can be done on neisseria meningitides but is not 100% reliable

A

Tumbler test – put a glass firmly up to the rash and if you can see the rash clearly through the glass then the test is positive – seek help

36
Q

prevention of neisseria meningitides

A

vaccination against serotype A, C, Y, and W135 which protects those 11-12 with a booster at age 16 but no protection against being a carrier

37
Q

names of the neisseria meningitides vaccination

A

–US: meningococcal polysaccharide vaccine (MPSV4- Menomune®)
– meningococcal conjugate vaccine (MCV4-Menactra® & Menveo®)