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micro test 3 > Lect 16 > Flashcards

Lect 16 Flashcards

1
Q

define meningitis

A

inflammation resulting from an infection within the subarachnoid space (houses CSF)

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2
Q

define encephalitis

A

inflammation in the parenchyma

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3
Q

define chronic meningitis

A

symptom progressive or persistence > or = 4 weeks

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4
Q

what major pathogen that causes meningitis has a vaccine

A

Haemophilus influenzae

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5
Q

what are the pathogens most responsible for community acquired meningitis

A
  • s. pneumoniae: most common cause of bacterial meningitis
  • H. influenza
  • N. menigitidis
  • *usually caused by organisms able to colonize the respiratory tract
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6
Q

list pathogenesis steps of bacterial meningitis

A
  1. mucosal colonization
  2. entry into bloodstream
  3. penetration of BBB
  4. release of inflammatory cytokines
  5. WBC diapedesis into CSF -> increased permeability of BBB
  6. exudation of serum -> edema, inc intracranial pressure, altered blood flow
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7
Q

What is the most common pathway for gaining access to the CNS

A
  • invasion of the bloodstream and seeding of the CNS
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8
Q

what is the classic triad of meningitis

A
  • fever
  • headache
  • neck stiffness
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9
Q

what are some additional signs and symptoms of NEONATAL bacterial meningitis

A
  • bulging fontanelle
  • high pitched cry
  • hypotonia
  • paradoxic irritability
    • quiet when stationary, crying when held
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10
Q

treatment of meningitis

A
  • prompt initiation of empiric therapy
  • steroids (usually dexamethasone)
  • intrathecal antibiotics for hospital acquired infections
    • injection into the spinal canal
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11
Q

what is purulent meningitis

A

intense acute congestion of meningeal blood vessels and purulent exudate

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12
Q

what are neonatal risk factors for meningitis

A
  • immaturity of host defense mechanism
  • low birth weight
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13
Q

what are maternal risk factors for neonatal meningitis

A
  • premature rupture of membranes
  • urogenital infection during late term
  • intrauterine infections during early term
  • invasion of the uterine space
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14
Q

neonatal meningits is characterized by what unique sign

A

Hyperthermia

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15
Q

what are the predominant agents of neonatal meningitis

A
  • streptococcus agalactiae: also known as group B streptococcus
  • E-coli
  • Listeria monocytogenes
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16
Q

CDC recommendations for prevention of neonatal meningitis

A
  • universal prenatal screening for vaginal or rectal colonization with group B strep for all pregnant woman at 35-37 weeks gestation
    • routine abx prophylaxis for culture + women
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17
Q

where are streptococcus agalactiae normally found

A
  • colonizes vagina, GI tract and upper respiratory tract of healthy individuals
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18
Q

streptococcus agalactiae

  • gram status
  • presentation on blood agar
A
  • gram positive coccus
  • gray white colonies with B hemolysis
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19
Q

virulence factors of streptococcus agalactiae

A
  • capsular polysaccharid
  • hyaluronidase
  • collagenase
  • hemolysin
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20
Q

early onset neonatal group B streptococcal infection

  • maternal complications?
  • when do symptoms develop?
A
  • maternal obstetric complications are common
  • symptoms develop during first 5 days of life
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21
Q

early onset neonatal group B streptococcal infection has what major clinical manifestations?

A
  • bacteremia
  • pneumonia
  • meningitis
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22
Q

late onset neonatal group B streptococcal infection has what major clinical manifestations?

A
  • bone/joint infections
  • bacteremia
  • concomitant/fulminant meningitis
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23
Q

late onset neonatal group B streptococcal infection

  • maternal complications?
  • when do symptoms develop
A
  • maternal obstetric complications are uncommon
  • symptoms develop from 7 days to 3 months of age
24
Q

How is S. agalactiae diagnosed?

A
  • definitive diagnosis requires isolation from blood, CSF
  • detection of CAMP factor
    • accentuation of hemolysis due to interaction with staph B-lysin
25
Q

E-coli

  • gram status
  • shape
A

gram negative enteric bacillus

26
Q

which strains of E-coli are associated with meningitis

A

encapsulated (K1) strains

27
Q

how do neonates get neonatal meningitis from E-coli

A
  • source is rectal colonization of mother’s vagina
  • **not an endogenous infection
28
Q

what is the most common cause of bacterial meningitis

A

S. pneumoniae

  • all ages are affected,
    • but it is the most common agent in the elderly
29
Q

what is the epidemiology of pneumococcal meningitis

A
  • acute purulent meningitis may follow pneumococcal PNA, infection at another site, or appear with no antecedent infection
30
Q

what are predisposing conditions for pneumococcal meningitis

A
  • multiple myeloma
  • sickle cell disease
  • cardiorespiratory disease
  • congenital defects
31
Q

Haemophilus influenzae

  • gram status
  • motile?
  • shape?
A
  • gram negative
  • non-motile
  • coccobacillus
32
Q

virulence factor of Haemophilus influenzae

A

contains LOS: lipooligosaccharide

33
Q

what is the usual clinical pattern of meningitis caused by Haemophilus influenzae

A
  • prior URI and associated or preceding otitis media
  • several days of mild antecedent infection
  • followed by deterioration, signs and symptoms of meningitis
34
Q

which causative agents of meningitis are more common in winter

A
  • N. meningitidis
  • S. pneumoniae
  • S. agalactiae
  • H. influenzae type B: late winter-early spring
35
Q

which causative agent of meningitis is most common in summer

A

L. monocytogenes

36
Q

meningitis caused by H. influenzae normally affected what patient population

A

infants (7-18 months)

37
Q

meningitis caused by N. meningitidis normally affected what patient population

A
  • 1 month old - 19 y.o
38
Q

meningitis caused by strep pneumoniae normally affects what patient population

A
  • 1 m.o - 4 y.o.
  • adults (especially elderly)
39
Q

meningitis caused by s. agalactiae normally affects what patient population

A
  • neonates < 1 m.o
  • adults
40
Q

meningitis caused by L. monocytogenes normally affects what patient population

A
  • newborns
  • predisposed adults
41
Q

L. monocytogenes

  • gram status
  • shape
  • motile
  • oxygen?
A
  • gram positive
  • motile
  • coccobacillus
  • non-fastidious and grows at temp 0-50 C
42
Q

how does Listeria monocytogenes exist in body

A
  • Facultative intracellular pathogen
    • in epithelial cells
    • in macrophages and monocytes
43
Q

where is Listeria monocytogenes found in environment

A
  • animal and human carriers
  • found in living and nonliving matter
    • vegetables
    • plants
    • soil
    • feces
44
Q

virulence factors of Listeria monocytogenes

A
  • lipopolysaccharide-like surface component
  • listeriolysin O
    • disrupts phagolysosome membrane
    • induces apoptosis
45
Q

how is Listeria monocytogenes infection gotten

A

ingestion of raw, contaminated food

46
Q

what are the two main manifestations of Listeria monocytogenes

A
  • sepsis
  • meningitis
47
Q

how do neonates get Listeria monocytogenes

A
  • acquired from mom’s genital tract -> results in meningitis
48
Q

what is the leading cause of meningitis in CA and renal transplant patients

A

Listeria monocytogenes

49
Q

how is Listeria monocytogenes diagnosed

A
  • culture
    • homogenization is required for tissues
  • “tumbling” motility in hanging drop preparation
50
Q

treatment of Listeria monocytogenes

A

DOC: IV ampicillin

51
Q

what is the causative agent of meningococcal meningitis

A

Neisseria meningitidis

52
Q

Neisseria meningitidis

  • gram status
  • capsule
  • most important serogroups
A
  • gram negative
  • encapsulated
  • A, B, C, Y, W135
53
Q

is there a vaccine for meningococcal meningitis

A
  • (A, C, Y, W135) is used for children, adolescents and person at high risk
  • new vaccine for serogroup B: Trumenba (pfizer)
54
Q

reservoir for meningococcal meningitis

A
  • humans
    • nasopharynx is colonized
55
Q

Clinical presentation

  • skin rash
    • petechiae and pink macules
  • DIC and gram negative shock can occur
A

meningococcal meningitis

56
Q

how is meningococcal meningitis diagnosed

A
  • gram stain of CSF
    • detection of capsular polysaccharide in CSF
  • chocolate agar and thayer-martin agar
    • supplemented with abx: vancomycin, colistin, bactrim
57
Q

how is meningococcal meningitis treated

A

DOC: penicillin G

micro test 3 (7 decks)

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