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Bacterial meningitis Flashcards

1
Q

Why is bacterial meningitis associated with elevated protein levels?

A

BBB breakdown

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2
Q

Causative agents of bacterial meningitis: 0-3 months

A

GBS (S. agalactiae)
Listeria
Gram - enterics (E. coli, Klebsiella, Enterobacter, Salmonella)

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3
Q

Causative agents of bacterial meningitis: 3 months - 2 years

A

H. flu B
N. meningitidis
Strep pneumo

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4
Q

Causative agents of bacterial meningitis: 2-18 years

A

S. pneumo

N. meningitidis

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5
Q

Causative agents of bacterial meningitis: 18+

A 
S. pneumo
N. meningitidis
Listeria
HIB
Gram - enterics
Pseudomonas
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6
Q

Causative agents of bacterial meningitis: immunocompromised patients

A

Staph
Gram - enterics
Pseudomonas

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7
Q

MCC bacterial meningitis 0-3 months

A

GBS

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8
Q

MCC bacterial meningitis 3 months-adulthood

A

S. pneumo

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9
Q

Strep pyogenes has which Lancefield antigen?

A

Rhamnose-acetylglucosamine

GAS

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10
Q

Step agalactiae has which Lancefield antigen?

A

Rhamnose-glucosamine

GBS

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11
Q

What are capsular polysaccharides used for diagnostically?

A

Determining types of strep pneumo

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12
Q

What are streptococci biochemical reactions used for diagnostically?

A

Strep that don’t have Lancefield antigens or specific hemolysis patterns, like strep viridans

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13
Q

What is Lancefield antigen?

A

An antigenic carbohydrate found in cell walls of strep

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14
Q

MCC invasive disease in children, elderly, and immunocompromised?

A

Strep

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15
Q

Place the diseases caused by strep in order of case fatalities

A

Meningitis (30%) > Sepsis (20%) > Pneumonia (5%)

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16
Q

What type of pneumonia does strep cause?

A

Lobar

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17
Q

Where do strep initially adhere?

A

Nasopharyngeal epithelium

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18
Q

How does strep cause middle ear inflammation?

A

Cell wall components cause cytotoxicity of ciliated cochlear cells

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19
Q

List 3 ways in which strep can invade.

A
  1. Alter vascular permeability and get into blood [pneumonia + bacteremia]
  2. Go though endothelial cells transcellularly and get into blood
  3. Bind to cerebral endothelial cells and transmigrate to enter CSF [meningitis]
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20
Q

How does the capsule of strep confer anti-phagocytic properties?

A

Prevents binding of C3b

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21
Q

List the 7 virulence factors of strep

A
  1. Capsule
  2. Pili
  3. Cell wall components
  4. Choline binding protein
  5. Hemolysin
  6. Neuraminidase and IgA protease
  7. H2O2
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22
Q

Which components of strep cell wall are proinflammatory?

A

Techoic and lipotechoic acids containing peptidoglycan and phophorylcholine

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23
Q

Which virulence factor of strep is important in crossing the BBB to cause meningitis?

A

Choline binding protein

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24
Q

What is the function of the choline binding proteins?

A

Adhesion

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25
What is the function of pneumolysin?
Lyse host cells and activate complement
26
What is the function of neuraminidase?
Invasion of host cells
27
What is the function of H2O2?
Bactericidal of competing organisms | Damage to host cells
28
Which strep pneumo vaccine is conjugated? What does this mean?
Prevnar - longer lasting immunity
29
Which type of molecules provide short-lived immunity? Memory?
Carbs | Proteins
30
Which S. pneumo vaccine is indicated for infants?
Prevnar
31
Which S. pneumo vaccine is indicated for asplenic patients?
Pneumovax
32
Which S. pneumo vaccine has an amnestic response?
Prevnar
33
Which S. pneumo vaccine is not effective in infants?
Pneumovax
34
Which S. pneumo vaccine has more capsule types?
Pneumovax (23 vs 13)
35
Morphology Strep vs. Neisseria
Strep = G+ diplococci, divide on a plane, capsule Neisseria = G- diplococci, divide as diplococci, +/- capsule (meningitidis has capsule, gonorrhoeae doesn't)
36
Rates of N. gonorrhoeae vs. N. meningitidis
N. gonorrhoeae = high prevalence, low mortality, not present in absence of disease N. meningitidis = low prevalence, high mortality, 5-30% carriage in persons without disease
37
How are N. meningitidis spp typed?
Based on their capsular polysaccharides into A, B, C, Y, W135
38
___% of patient with meningococcus die despite Abx
10-15%
39
___% of surviving patients with meningococcus have long-term sequela, including:
10% | Lose arms or legs, deaf, mentally retarded, seizures, strokes, nervous system problems
40
An 18 yo college students presents with nuchal rigidity, HA, fever. Which meningococcal serotypes do you expect?
B, C, Y
41
Which meningococcal serotype is associated with meningitis epidemics? Where is this especially prominent?
``` A Subsaharan Africa ("Meningitis Belt") ```
42
Describe the development of fulminant meningococcal meningitis
Abrupt onset neck stiffness, fever, chills, N/V Mental status change within a few hours (apprehension, confusion, delerium, coma) Petechia, purpuric rash Pulmonary insufficiency within a few hours Death
43
What are the early signs of meningococcal meningitis? Late?
Neck/back stiffness, mental changes = early | Rash = late
44
List the 4 virulence factors of N. meningitidis
1. Capsule 2. Pili 3. Endotoxic LOS 4. Phase variation
45
What is the only known reservoir for meningococcus?
Human nasopharynx
46
How is meningococcus spread?
Aspiration
47
Which symptoms are unique to meningococcemia vs meningococcal meningitis?
Meningococcemia = diarrhea, cramps, spots/rash Meningitis = photophobia, severe HA, stiff neck
48
DOC meningococcemia vs. meningitis?
DOC for both is PCN
49
Why do neither meningococcal vaccines cover group B?
It's capsular polysaccharide is a polymer of sialic acid, which is not immunogenic to humans
50
What are the big differences between menomune and menactra?
Menomune is unconjugated so has short-lived immunity; menactra is conjugated so has anamnestic response Menomune is only given to high risk pt's, cochlear transplant patients, and those traveling to subsaharan africa (group A epidemic); menactra is suggested for anyone 11-55 years old
51
Which serogroups are covered by both menomune and menactra?
A, C, Y, W135
52
Describe phase variation
N. meningitidis can turn genes on or off | ex. turning genes off so it can inavde then back on once in bloodstream
53
Describe antigenic variation. Which N. meningitidis system uses this mechanism?
Changes in a gene leads to expression of a different form; pili - move silent loci into expression loci for antigenically different loci
54
Why is Hib infection uncommon prior to 3 months of age?
Maternal antibodies
55
What is the chief virulence factor of Hib? What is unique about it?
Capsule | Polysaccharide antigens are T cell independent so immunity is short-lived
56
Describe the Hib vaccine. Who gets it?
Type b polysaccharide capsule (PRP) conjugated to diphtheria toxin Infants 2-15 months
57
Does the Hib vaccine offer anamnestic response?
Yes - conjugated to diphtheria protein
58
___% of kids with Hib meningitis die. ___% develop severe sequela.
5% die | 15-30% have neurological sequela
59
Morphology of H. flu?
Gram - coccobacillus
60
Morphology of Listeria?
Gram + rod
61
Who gets Listerosis?
Infants, immunocompromised, pregnant women
62
What do immunocompotent patients with Listerosis experience?
Mostly asymptomatic, can experience mild flu-like sx, occasionally diarrhea and abdominal pain
63
What do infants, immunocompromised, pregnant women with Listerosis experience?
Meningitis and bacteremia
64
How do neonates contract Listerosis?
Vaginal canal of mother
65
What are the two human sources of Listeria?
Vagina and intestines
66
Which two animal sources are associated with Listerosis?
Sheep and chickens
67
What food sources are associated with Listerosis?
Raw veggies, dairy (soft cheeses), meat (sheep, chicken)
68
Prognosis of intrauterine Listerosis?
Death
69
What is the problem with decontaminating food suspected of harboring Listeria?
Listeria can be killed by pasteurization but may replicated during refrigeration, amplifying the bacterial load during storage
70
What cell types does Listeria invade?
Macrophages and endothelial cells
71
Describe the invasion scheme of Listeria
1. Internalin binds to E-cadherin on epithelial cells 2. Escapes phagolysosome via Listeriolysin O 3. Polyermization of F-actin propels bug into adjacent cell 4. Replicates 5. Cell death
72
What is the purpose of intracellular spread of Listeria?
Evades host immune system
73
What is necessary to kill Listeria?
Cytokine activation of macrophages
74
"Tumbling motility"
Listeria and trich
75
Trimethoprim-sulfamethoxazole can prevent which two infections in AIDS patients?
Listerosis, pneumocystis

Neuro (5 decks)

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