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Micro > Nervous System Infections > Flashcards

Nervous System Infections Flashcards

1
Q

what causes meningitis

A

bacteria, viruses, or fungi

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2
Q

what is the diagnostic testing for meningitis

A

lumbar puncture
- direct sampling of CSF
- CSF can be analyzed for by culture and gram stain

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3
Q

the causes of meningitis depends on

A

age and risk factors

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4
Q

what is the risk factor for cryptococcus meningitis

A

HIV

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5
Q

what are the three most common bacterial causes of meningitis

A
  1. strep pneumonia
  2. neisseria meningitides
  3. haemophilus influenzae type B
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6
Q

which bacteria are part of the normal microbiota of the URT and how are they transmitted

A
  • s. pneumonia
  • neisseria meningitides
  • haemophilus influenzae type B
    • through contact with respiratory droplets
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7
Q

when can bacterial meningitis spread from URT to the blood

A

depends on the invasive potential of the bacterial strain and the immune status of the host

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8
Q

how does bacterial meningitis get into the blood and what happens when it does

A
  • capsule helps evade phagocytosis and virulence factor that evades mucosal IgA antibodies
  • enter bloodstream
  • cross BBB (blood-brain barrier) to meninges
  • triggers inflammation
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9
Q

are gonococcal infections most often local and rarely lethal

A

yes

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10
Q

when meningococcal infection enters the bloodstream does it become systemic and a life-threatening disease

A

yes

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11
Q

what is the shape of neisseria meningitidis

A
  • encapsulated
  • gram-negative diplococci
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12
Q

does gonococci have a capsule

A

no

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13
Q

what are the functions of the capsule and IgA protease of neisseria meningitidis

A
  • capsule protects from phagocytosis and the complement system
  • IgA protease destroys IgA antibodies
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14
Q

what is the epidemiology of meningococcal meningitis

A
  • many people are asymptomatic carriers -> part of the microbiota in pharynx
  • transmission via contact with respiratory droplets
  • remains endemic in sub-Saharan Africa
  • epidemics occur in U.S. as it spreads among people living in close contact (college dorms and army barracks)
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15
Q

what are signs/symptoms of meningococcal meningitis

A
  • early symptoms = common cold
  • acute onset of severe throbbing headache and stiff neck
  • symptoms quickly escalate: confusion, coma, endotoxic shock, and death can occur within hours
  • long term effects: hearing loss, brain damage, amputation, and nervous system problems
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16
Q

what happens after meningococcal meningitis bacteria infect the URT and enter the blood

A

they damage skin capillaries
- the tiny hemorrhages appear as petechiae on the legs and feet
- usually NOT present in other forms of meningitis

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17
Q

what kind of vaccine is used against serogroup B of N. meningitides

A
  • conjugate vaccine consisting of purified capsular polysaccharides from four serogroups (A,C,W,Y)
  • a subunit recombinant protein vaccine for serogroup B
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18
Q

who is prophylactic vaccination recommended for

A

to first-year college students living in dorms

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19
Q

what is the treatment for meningococcal meningitis

A
  • antibiotics given while cause being determined
    • if untreated, case-fatality rate can approach 100%
    • even with treatment, 10-20%
  • survivors may suffer permanent disabilities
  • antibiotic prophylaxis = recommended for close contacts to those diagnosed to prevent the disease
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20
Q

what is the shape of pneumococcal meningitis

A

aka strep pneumoniae
- encapsulated
- gram-positive lancet-shaped diplococci

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21
Q

where is pneumococcal meningitis found

A

in the microbiota of the pharynx

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22
Q

how is pneumococcal meningitis transmitted

A

via contact with respiratory droplets

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23
Q

what is the number overall cause of bacterial meningitis to children, young adults, adults, and the elderly

A

pneumococcal meningitis

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24
Q

what are s. pneumoniae virulence factors

A
  • the capsule helps the bacteria evade phagocytosis when it gets into the bloodstream -> spreads to meninges
  • produces choline-binding proteins (cbpA) that interfere with IgA antibody function
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25
Q

what are some signs/symptoms of pneumococcal meningitis

A

similar to meningococcal meningitis
(throbbing headache and common cold at first)
- often distinguished by lack of petechiae and endotoxic shock

26
Q

what is the prevention of pneumococcal meningitis for adults

A

capsular polysaccharide vaccine against 23 pneumococcal strains that cause over 90% of disease

27
Q

what is the prevention of pneumococcal meningitis for infants and children

A

conjugate vaccine against 13 strains

28
Q

what is the shape of haemophilus influenza type B (Hib)

A
  • encapsulated
  • gram-negative coccobacillus
29
Q

true or false - haemophilus influenzae that causes pneumonia is not encapsulated and that’s the distinguishing factor from Hib

A

true

30
Q

Hib causes meningitis in

A

babies and young children (<5 years)

31
Q

the adult carriers of Hib often are a source of infection by transmitting through

A

contact with respiratory droplets

32
Q

what are the virulence factors of Hib

A

capsule and IgA protease

33
Q

what are the signs/symptoms of Hib meningitis

A
  • begin with mild cold; progress to severe headache, fever, vomiting
  • older children may have stiff neck
  • infants may show bulging fontanelle (gap btwn plates of skull) and may have a rigid body with arched back and head thrown backward
  • untreated case-fatality rate ~90%
34
Q

describe the Hib vaccine

A
  • pre-vaccine era: HiB caused meningitis in 1 out of 200 children under age 5
  • conjugate Hib vaccine has type b polysaccharide bound to bacterial protein
  • reduced incidence over 99%
35
Q

how is neonatal meningitis acquired

A

during birth (listeria can cross placenta)

36
Q

what are some common pathogens of neonatal meningitis

A
  • strep agalactiae (GBS)
  • listeria monocytogenes
  • e. coli
37
Q

what are signs/symptoms of neonatal meningitis

A
  • bulging fontanel (swelling at the soft spot)
  • stiff neck
  • lethargy, sleepiness
  • rigid body with arched back and head thrown backward
  • poor feeding
  • temperature instability
38
Q

what is the shape of s. agalactiae (ie group B strep)

A
  • encapsulated
  • gram-positive cocci arranged in chains
39
Q

what is the most common cause of neonatal meningitis

A

s. agalactiae (GBS)

40
Q

true or false - s. agalactiae is part of the women’s transient vaginal microbiota; mother passes it to the baby during birth (bacteremia leads to infection of meninges)

A

true

41
Q

is there a vaccine for s. agalactiae

A

no

42
Q

what is the shape of e. coli meningitis

A
  • encapsulated
  • gram-negative rods
43
Q

what is the second most common cause of neonatal meningitis

A

e. coli meningitis

44
Q

true or false - NMEC (neonatal E. coli pathovar) is part of the women’s transient vaginal and intestinal microbiota

A

true

45
Q

who is the high risk group for neisseria meningitides

A

children and young adults

46
Q

who is the high risk group for Hib

A

children <5 years

47
Q

who is the high risk group of s. pneumoniae

A

adults and young adults

48
Q

who is the high risk group for s. agalactiae

A

neonates

49
Q

who is the high risk group for e. coli

A

neonates

50
Q

describe viral meningitis

A
  • usually clears up in a week or two with no specific treatment
  • common; rarely serious
  • increased lymphocytes rather than neutrophils in CSF
51
Q

which meningitis is considered a type of aseptic meningitis

A

viral meningitis

52
Q

viral meningitis is caused by a number of different viruses, describe them

A
  • coxsackie A and B viruses are pretty common
  • spread via fecal contamination of food, water, or hands
53
Q

what fungal pathogen causes meningitis

A

cryptococcus neoformans

54
Q

true or false - cryptococcus neoformans is an encapsulated yeast

A

true

55
Q

what kind of fungal pathogen is cryp neoformans

A

opportunistic

56
Q

what is the function of the capsule in cryp neoformans

A

inhibits phagocytosis

57
Q

describe cryptococcus epidemiology

A
  • typically found in soil or in bird (pigeon) droppings
  • non-communicable (can’t go from person to person)
  • airborne transmission: inhaling dust contaminated with the yeast
  • infects the lung but is usually mild or asymptomatic in otherwise healthy individuals
58
Q

describe cryptococcosis epidemiology

A
  • rare until AIDS epidemic
  • it is the most common potentially fatal fungal infection in AIDS patients
    • symptomatic infection sometimes first indication of
      AIDS
  • low CD4 count predisposed to severe cryptococcal infection
59
Q

what are signs/symptoms of cryptococcosis

A
  • in immunocompromised, infection starts in lungs:
    • pulmonary cryptococcosis: chronic pneumonia-like
      illness with cough, fever, and lung nodules
  • in immunocompromised, infection spreads from lungs via blood to meninges
    • cryptococcal meningitis
60
Q

what are signs/symptoms of cryptococcal meningitis

A
  • headache, fever, neck pain, nausea and vomiting, confusion or changes in behavior, can also spread to surround brain tissue to cause meningocephalitis

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