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Block 8 Week 2 > Kozel: CNS Infections > Flashcards

Kozel: CNS Infections Flashcards

1
Q

List 5 routine CSF tests

A
  1. WBC with differential
  2. Glucose concentration
  3. Protein concentration
  4. Gram stain
  5. Bacterial culture
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2
Q

What should the [glucose] be in the CSF?

A

60% of plasma levels - 50-80mg/dL

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3
Q

In viral meningitis, what will WBC count be? What type of cell will be infiltrating? What will glucose levels be like? Protein levels?

A

WBC: 50-1000
Cells: mononuclear
Glucose: >45
Protein: <200

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4
Q

In bacterial meningitis, what will WBC count be? What type of cell will be infiltrating? What will glucose levels be like? Protein levels?

A

WBC: 1000-5000
Cells: neutrophilic
Glucose: <40
Protein: 100-500

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5
Q

In tuberculous meningitis, what will WBC count be? What type of cell will be infiltrating? What will glucose levels be like? Protein levels?

A

WBC: 50-300
Cells: mononuclear
Glucose: <45
Protein: 50-300

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6
Q

In crytococcal meningitis, what will WBC count be? What type of cell will be infiltrating? What will glucose levels be like? Protein levels?

A

WBC: 20-500
Cells: mononuclear
Glucose: 45

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7
Q

If the WBC count is elevated in CSF, what does this imply?

A

inflammation and immune response

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8
Q

If glucose is decreased in the CSF, what are three potential causes?

A
  1. increased glycolysis by leukocytes and bacteria
  2. increased metabolic rate of brain and spinal cord
  3. altered glucose transport b/w blood and CSF
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9
Q

If protein is increased in the CSF, what does this imply?

A

disruption of BBB

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10
Q

When is a lumbar puncture contraindicated?

A
  1. papilledema - increased cranial pressure

2. neurological suggestion of intracranial mass

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11
Q

inflammation of protective membranes covering brain and spinal cord – meninges

A

acute meningitis

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12
Q

any meningitis for which a cause is not apparent after routine stains and culture of CSF

A

aseptic meningitis

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13
Q

Symptoms of acute meningitis? Start with the triad of symptoms…

A

headache, neck stiffness + fever
confusion and altered mental status
vomiting
photophobia or phonophobia

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14
Q

What are 3 steps in the initial management of acute meningitis?

A
  1. lumbar puncture + CSF analysis
  2. empiric antimicrobial therapy based on patient age
  3. may use dexamethasone if appropriate
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15
Q

Viruses are the most common cause of meningitis. List 3 viruses that can cause acute meningitis.

A
  1. enteroviruses
  2. mumps virus
  3. herpesvirus
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16
Q

5 bacterial causes of acute meningitis?

A
  1. S. pneumo
  2. N. meningitidis
  3. S. agalactiae
  4. H. influenzae
  5. L. monocytogenes
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17
Q

2 spirochetes that can cause acute meningitis?

A

Treponema pallidum

Borrelia burgdorferii

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18
Q

Mucosal/nasopharyngeal colonization
Local invasion
Intravascular survival
Meningeal invasion – Moxon experiment
Induction of subarachnoid space inflammation
Alterations of blood-brain barrier
Cerebral edema and increased intracranial pressure
Vasogenic – increased BBB permeability
Cytotoxic – swelling of cellular elements of brain
Interstitial – obstruction of normal flow of CSF

A

bacterial meningitis

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19
Q

Bacterial meningitis can induce inflammation of the (blank) and may alter the (blank)

A

subarachnoid space; BBB

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20
Q

At a young age (<1 month - 23 months), what bacteria are most likely to cause meningitis?

A

Strep agalactiae

E. coli

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21
Q

At an “older age” (2-50+ years), what bacteria are most likely to cause meningitis?

A

S. pneumo

N. meningitidis

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22
Q

How do antibiotics penetrate the BBB?

A

inflammation disrupts BBB

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23
Q

What do corticosteroids do in cases of meningitis?

A

reduce inflammation, reduce CNS penetration

**antibiotics less likely to get across BBB

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24
Q

What are features of antibiotics with good BBB penetration in absence of meningeal inflammation?

A 
low molecular weight
low degree of ionization at phys pH
high lipid solubility
low degree of protein binding
absence of active efflux systems
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25
Q

If <1 month, how should you treat bacterial meningitis?

A

ampicillin + cefotaxime (binds PCPs and blocks cell wall synthesis)

or

ampicillin + an aminoglycoside (blocks 30s ribosome)

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26
Q

If 1 month to 50 years old, how should you treat bacterial meningitis?

A

vancomycin + third gen cephalosporin

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27
Q

If 50+, how should you treat bacterial meningitis?

A

vancomycin + ampicillin + third gen cephalosporin

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28
Q

For a patient with meningitis caused by Strep pneumo, prescribe (blank)

A

vancomycin + third gen cephalosporin

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29
Q

For a patient with meningitis caused by Neisseria meningitidis, H. influenzae, or E. coli, prescribe (blank)

A

third gen cephalosporin

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30
Q

For a patient with meningitis caused by Listeria monocytogenes or Step agalactiae, prescribe (blank)

A

ampicillin or penicillin G

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31
Q

How is chronic meningitis different from acute meningitis?

A
  1. onset is more gradual
  2. fever is lower
  3. associated with lethargy and disability
  4. often immunocompromised
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32
Q

What can cause chronic meningitis?

A

mycoses - cyrptococcosis, coccidiomycosis, histoplasmosis, candidiasis

bacteria - M. tuberculosis, T. pallidum, B. burgdorferi

parasites

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33
Q

Inflammatory process of the brain parenchyma

Clinical or lab evidence of neurologic dysfunction

A

encephalitis

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34
Q

Symptoms of encephalitis?

A

fever and headache

**altered mental status

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35
Q

What will the CSF be like in encephalitis?

A 
increased lymphocytes (lymphocytic pleocytosis)
normal glucose (as opposed to increased in bacterial meningitis)
elevated protein
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36
Q

What most commonly causes encephalitis?

A

viruses: herpesvirus, arboviruses, HIV, enteroviruses, rabies virus

37
Q

focal, intracerebral infection that begins as a localized area of cerebritis and develops into collection of pus surrounded by a well-vascularized capsule

A

brain abscess

38
Q

What are 3 sources of brain abscess?

A
  1. contiguous spread - sinusitis, otitis media
  2. hematogenous
  3. trauma
39
Q

Symptoms of brain abscess?

A

headache
nausea
vomiting
focal neuro findings

**varies with site of abscess

40
Q

When bacteria are involved in brain abscesses, it’s usu a mixed infection. Which organisms are involved in most cases of brain abscess?

A
  1. streptococcus spp (70%)

2. S. aureus (10-20%)

41
Q

Which fungi are most commonly involved in a brain abscess?

A 
Aspergillus
Candida
Crypto
Mucorales
Coccidioides
42
Q

T/F: The bacteria involved in brain abscesses vary depending on the predisposing conditions, ex: sinus infection vs penetrating trauma will involve different bacteria.

A

True

43
Q

What three mediums can be used to isolate Neisseriaceae?

A

blood
chocolate agar
Thayer-Martin medium **inhibits normal flora

44
Q

What do Neisseriaceae produce, which can be used for identification?

A

indophenol oxidase

45
Q

Meningitis is predominantly found in this area

A

sub-Saharan Africa

46
Q

What is the classic epidemic strain of N. meningitidis?

A

Group A capsular polysaccharide

47
Q

3 antigenic structures of N. meningitidis?

A

Group specific capsular polysaccharide
Type specific outer membrane protein
Type specific lipooligosaccharide

48
Q

What are 3 meningococcal infections?

A
  1. meningococcemia - may occur with or w/o meningitis
  2. meningitis
  3. petechial lesions
49
Q

4 virulence factors of Neisseria meningitidis?

A
  1. antiphagocytic capsule
  2. lipooligosaccharide
  3. outer membrane proteins
  4. pili
50
Q

Extremely toxic virulence factor of Neisseria meningitidis; produces inflammation; contains lipid A and core oligosaccharide; released from the bacterial surface as membrane blebs

A

lipooligosaccharide

51
Q

Where does N. meningitidis adhere in carriers? How does it adhere? It can remain local, but it can also spread. Where does it spread?

A

to the nasopharynx; adheres via pili; spreads via lymphatics to blood and meninges

52
Q

What does the capsule of N. meningitidis do?

A

prevents phagocytosis and complement mediated lysis

53
Q

What does lipooligosaccharide cause?

A

tissue damage and DIC

54
Q

Multiple attacks of N. meningitidis are associated with deficiencies in (blank)

A

terminal complement proteins - C5-C9

55
Q

What are some ways in which you can identify N. meningitidis in the lab?

A
  1. specimens: blood, CSF, nasopharyngeal secretions
  2. direct examination: gram stain of CSF
  3. isolation: culture, incubate in CO2, grow on blood agar, Thayer Martin, or chocolate agar
56
Q

What are some differential tests that can be used to confirm N. meningitidis infection?

A

gram negative diplococci
oxidase positive
oxidative production of acid from sugars like glucose

57
Q

How is N. meningitidis transmitted?

A

man to man transmission via airborne droplets

58
Q

Who is most susceptible to N. meningitidis infections?

A 
young children (lack antibody)
college students
military recruits (crowding, fatigue)
microbiologists w potential exposure
travelers to endemic regions
people with terminal complement deficiencies
no spleen
59
Q

Meningococcal disease is most likely to occur during months (blank) to (blank) of life as transplacental antibody is wearing off

A

6-12 months

60
Q

What is the major factor that determines if a person is resistant or susceptible to meningococcus infection? How do you get protection to different types of capsular antigen? What explains the risk of childhood infection b/w ages 6-24 months?

A

anticapsular antibody; exposure in our normal flora to something that looks like that polysaccharide antigen; lack of antibody explains the risk of children b/w 6-24 months

61
Q

How is the meningococcal vaccine different now than it was in 1981?

A

it used to be a purified polysaccharide alone, but now it is a polysaccharide-protein conjugate vaccine; also the vaccine is now routinely given at 11-12 years of age with a booster at 16-18 years

62
Q

What type of vaccine is the meningococcus vaccine?

A

multivalent purified capsular polysaccharide - capsular polysaccharide-protein conjugate

63
Q

What is the standard therapy for N. meningitis if it is identified?

A

third generation cephalosporin ex: ceftriaxone/cefotaxime

or

penicillin G or ampicillin

**readily penetrates inflamed meninges

64
Q

What can be used for family contacts of those with meningitis or in epidemic cases?

A

chemoprophylaxis - rifampin (disrupts RNA polymerase)

65
Q

How to treat meningitis if <1 month old?

A

ampicillin + cefotaxime

or

ampicillin + aminoglycoside

66
Q

How to treat meningitis if 1-50 years old?

A

vancomycin + third gen cephalosporin

67
Q

How to treat meningitis if >50 years old?

A

vancomycin + ampicillin + third gen cephalosporin

68
Q

Describe Hemophilus influenzae morphologically

A

very small gram negative rods

69
Q

2 nutritional requirements for H. influenzae?

A

X factor - hematin; found in blood

V factor - NAD

70
Q

What type of agar is good to grow H. influenzae? What must be done to the blood agar? What is another way to grow H. influenzae?

A

chocolate agar; it must be heated to lyse RBCs and release factors X and V; you can also grow it in the presence of S. aureus - this is called satelliting

71
Q

Grows with S. aureus - satelliting - releases X and secretes factor V

A

H. influenzae

72
Q

What is the antigenic structure notable on H. influenzae?

A

capsular polysaccharide - types a-f

**not all strains have a capsule - some are nontypeable

73
Q

This type of H. influenzae polysaccharide causes almost all systemic/invasive disease; polyribitol phosphate

A

type b

74
Q

What does H. influenzae infection cause?

A

nasopharyngitis extending to middle ear, blood and meninges, or joints (usu due to nontypeable strain)
epiglottitis (due to encapsulated strains)
pneumonia (not common)

75
Q

Headache + nuchal rigidity + fever + altered mental status is more indicative of (blank)

A

encephalitis

76
Q

Two virulence factors of H. influenzae?

A

antiphagocytic capsule

endotoxin which induces meningeal inflammation

77
Q

Where to get a specimen for H. influenzae?

A

nasopharyngeal swab
blood
CSF

78
Q

What does culture of H. infleunzae require?

A

X and V factors
chocolate agar
or S. aureus - satellite phenomenon

79
Q

H. influenzae colonizes the (blank), and is usually a (blank) strain

A

upper resp tract; nontypeable

**requires type b to cause invasive disease

80
Q

Why are most of us >3yo resistant to H. influenzae?

A

natural antibody which protects by opsonization and complement mediated lysis;
Maternal antibody protects < 6 months
Exposure to Hib carriers and cross-reactive antigens protects children > 3 yrs

81
Q

What type of vaccine is the H. influenzae vaccine?

A

capsular polysaccharide-protein conjugate

82
Q

How to treat Hib infection?

A

prompt vigorous treatment with a broad spectrum cephalosporin with good CNS penetration (ex: cefotaxime or ceftriaxone)

83
Q

What to give carriers of Hib infection?

A

rifampin

84
Q

What to give susceptible contacts of those with Hib infection?

A

chemoprophylaxis

85
Q

What does H. influenzae biogroup aegyptius cause?

A

Brazilian purpuric fever - acute onset of fever, vomiting, abdominal pain, followed by purpura, vascular collapse and death

86
Q

What does Hemophilus aegyptius cause?

A

acute, purulent conjunctivitis (pink eye)

87
Q

What does Hemophilus ducreyi cause?

A

chancroid (soft chancre) - painful ulcers on genitalia

88
Q

Where is Hemophilus ducreyi commonly seen?

A

in Africa

**probable co-factor in transmission of AIDS

Block 8 Week 2 (10 decks)

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