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Microbio > Bacterial infx CNS > Flashcards

Bacterial infx CNS Flashcards

1
Q

What are the two categories of CNS infections?

A
  1. Those involving the meninges (meningitis)

2. Those which are confined to the brain (encephalitis)

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2
Q

What is the blood-brain barrier? What are the three functions it provides?

A

1 Separates blood and CSF

  1. Provides physical isolation for the CNS
  2. Protects the CNS, but not the PNS
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3
Q

What must microbes be able to do to cause CNS infections?

A

Disrupt the BBB

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4
Q

What is the BBB made of?

A

Tight junctions between endothelial cells and the cerebral microvasculature, cpithelial cells of the chorid plexus, and arachoind cells

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5
Q

What two features of the epithelial cells that comprise the BBB make them a good barrier?

A
  1. Tight junctions

2. Little pinocytosis/channels

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6
Q

How do CNS infections usually start? (3)

A
  1. Bacteremia or spread from a site adjacent/contiguous with the CNS
  2. Direct inoculation (rare)
  3. Neuronal spread
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7
Q

What are the three categories of meningitis? What are the usual causes of each?

A
  1. Acute pyogenic (bacterial)
  2. Aseptic (viral)
  3. Chronic (any class)
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8
Q

Bacterial meningitis is more or less fatal than viral?

A

More

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9
Q

What are the predisposing factors to pneumococcal meningitis? (2)

A

Pneumonia and chronic OM

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10
Q

What are the predisposing factors to meningococcal meningitis? (2)

A
  1. h/o recent URI (viral)

2. Complement deficiencies

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11
Q

Which type of meningitis occurs frequently in complement deficiencies?

A

Meningococcal

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12
Q

Where/when are meningococcal outbreaks (specifically) common?

A

Schools and military barracks

Winter months

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13
Q

What are the two common features of the bacteria that cause meningitis?

A
  1. Capsule

2. Fimbrae/pili

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14
Q

What is the function of the capsule of the meningitis-causing bacteria?

A

Resists immune mechanisms that allows them to travel to the CNS

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15
Q

What is the function of the fimbrae/pilli of the meningitis-causing bacteria?

A

help colonize the CNS cells

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16
Q

What are the two main things that cause the damage with meningitis?

A
  1. Toxins

2. Immune response

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17
Q

What is the significance of the bacterial toxins?

A

Incude the production of cytokines

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18
Q

What is the function of the cytokines released?

A

Cause inflammation and edema in the CNS

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19
Q

What are the four common symptoms of meningitis?

A
  1. Fever
  2. HA
  3. Stiff neck
  4. AMS
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20
Q

How do you diagnose meningitis? (3)

A
  1. Gram stain CSF
  2. Cultures
  3. Latex agglutination
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21
Q

What is the treatment for meningitis? What is this based on?

A

Empiric abx

Examination of CSF, age, preexisting conditions

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22
Q

The majority of cases of bacterial meningitis occur in what population group?

A

infants and children

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23
Q

What is the most (and second most) common pathogen of bacterial meningitis?

A
  1. Strep pneumonia

2. Neisseria meningitidis

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24
Q

What percent of meningitis are caused by Strep agalactiae?

A

5-10%

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25
Q

What percent of meningitis are caused by listeria monocytogenes?

A

5-10%

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26
Q

What percent of meningitis are caused by H/influenzae?

A

5-10%

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27
Q

What percent of meningitis are caused by Strep pneumonia?

A

50%

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28
Q

What percent of meningitis are caused by N.meningitidis?

A

25%

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29
Q

Kids less than 2 month of age (or 2 yo) are have bacterial meningitis caused by what pathogen?

A

Strep agalactiae

30
Q

What are the four major causes of bacterial meningitis in neonates?

A
  1. Strep agalactiae
  2. E.coli
  3. Gram negative enterics
31
Q

What is the gram stain and morph of strep pneumonia? Catalase?

A

Gram positive cocci, catalase negative

32
Q

What is the hemolysis patterns seen in strep penumo? Is it optochin sensitive? bile?

A

alpha

Sensitive to bile and optochin

33
Q

Who are more frequently colonized by strep pneumonia kids or adults?

A

Kiddos

34
Q

What are the three virulence factors that strep pneumo produces to help them spread in the body?

A
  1. IgA protease
  2. Pneumolysin
  3. Capsule
35
Q

How fast is the onset of pneumococcal meningitis?

A

hours

36
Q

How do you diagnose pneumococcal meningitis?

A

Gram stain CSF

Latex agglutination

37
Q

What does the latex agglutination test detect in pneumococcal meningitis?

A

Capsular antigens

38
Q

What is the treatment for meningitis?

A

Initially vanco with a cephalosporin

Later with more targeted

39
Q

How do you prevent pneumococcal meningitis?

A

Vaccination

40
Q

What does the vaccine against pneumococcal meningitis contain?

A

Purified capsular polysaccharide from 23 types of pneumococcus

41
Q

Why is the vaccine for pneumococcal meningitis not effective in children?

A

They have a problem developing antibodies to polysaccharides

42
Q

What are the recommendations for the PPV vaccine?

A

Adults >65 yo

Persons >2 with chronic illness or likely exposure

43
Q

What is PCV13 used in the pneumococcal vaccine?

A

Pneumococcal polysaccharide conjugated to nontoxic diphtheria toxin

44
Q

What is the gram stain and morph of Neisseria meningititidis? (key shape)

A

Gram negative diplococci with coffee bean appearance

45
Q

What are the two virulence factors for N.Meningitidis?

A
  1. LOS

2. Capsule

46
Q

Coffee/kidney bean appearing bacteria = ?

A

N. Meningitidis

47
Q

How do you differentiate between N. Meningitidis vs gonorrhea?

A

Oxidizes both glucose and maltose

48
Q

Is N. Meningitidis oxidase positive? Catalase?

A

Both positive

49
Q

What type of agar is needed for N. Meningitidis?

A

Chocolate agar

50
Q

Do we have vaccines against N. Meningitidis?

A

Four of the five common ones

51
Q

How is N. Meningitidis transmitted?

A

Coughs, secretions etc

52
Q

What are the serotypes of N. meningitidis most often causes disease? (5) Which one do we not have a vaccine against?

A
  1. C
  2. B** no vaccine
  3. Y
  4. W
  5. A
53
Q

What are the significant sequelae of N. Meningitidis infections?

A

Neuro deficits

Limb amputation

54
Q

What are the symptoms of meningococcal disease besides HA, stiff neck? (3)

A

Abrupt fever, hypotension, rash

55
Q

How do you diagnose Meningococcal meningitis?

A
  1. gram stain CSF

2. Antigen detection in CSF

56
Q

What percent of patients with only bacteremia caused by meningococcal have detectable organisms in blood smears?

A

30%

57
Q

What is the treatment for meningococcal meningitis? (initially vs confirmed Meningococcal)

A

Vanco initially,

Penicillin if confirmed Meningococcal disease

58
Q

What are the two types of vaccine against meningococcal disease? Which is actually used?

A

tetravalent polysaccharide only used for immune suppressed

(MCV4) Tetravalent polysaccharide conjugate vaccine = actually used

59
Q

How many doses of the vaccine against meningoccal disease ?

A

one dose in 2-5 years if indicated

60
Q

What is the conjugated polysaccharide that the meningococcal vaccine is conjugated to?

A

Diptheria toxin subunit

61
Q

Which type of meningitis displays decreased glucose levels in the CSF: bacterial or viral?

A

bacterial

62
Q

Which type of meningitis displays increased protein levels in the CSF: bacterial or viral?

A

Bacterial

63
Q

Which type of meningitis displays increased pressure in the CSF: bacterial or viral?

A

Bacterial

64
Q

Which type of meningitis displays increased levels of mom/lymphocytes: bacterial or viral?

A

Viral

65
Q

Which type of meningitis displays increased levels PMNs: bacterial or viral?

A

Bacterial

66
Q

If a pt presents with meningitis, without knowing anything else, what is the most likely cause of it? What is it’s a kid <2 yo (or months

A

Strep Pneumonia

GBS for kiddos

67
Q

What is the gram stain and morphology of listeria?

A

Gram positive rod

68
Q

What is the gram stain and morphology of HiB?

A

Gram negative rod

69
Q

What groups of people is Listeria a major factor for meningitis?

A

Very young and old

70
Q

Bile test is used to differentiate between what pathogens?

A

Strep and enterococcus

71
Q

What bacteria need chocolate agar?

A
  1. Neiserria

2. Heamophilus

72
Q

Does the MCV4 vaccine against N. Meningiditis work well?

A

Yes, IgG and goodness

Microbio (50 decks)

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