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Neurology > Bacterial CNS > Flashcards

Bacterial CNS Flashcards

1
Q

4 major causes of bacterial meningitis

A

Strep pneumo, neisseria meningitidis, H Flu, Listeria monocytogenes

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2
Q

CSF in bacterial meningitis usually associated with

A

large numbers of polys
reduced glucose
elevated protein

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3
Q

Streptococci morphology

A

Gram positive spherical bacteria that occur in pairs

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4
Q

strep pneumo

A
  • also known as pneumococcus

- Normal inhabitants of the upper respiratory tract but MOST COMMON cause of bacterial meningitis in US

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5
Q

Strep pyogenes

A

Also known as group A strep, also normal inhabitants of URT

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6
Q

Strep Agalactiae

A

Group B strep

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7
Q

Viridans Streptococci

A

dental pathogen

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8
Q

Lancefield classification

A

An antigenic carbohydrate found in cell walls that determines the Lancefield groups

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9
Q

Capsular polysaccharide is used to classify what?

A

Antigenic specificity of S. Pneumoniae

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10
Q

Strep pneumo disease

A
  • pneumonia (lobar type)
  • bacteremia (invasion of tissues and multiplication in the blood)
  • Otitis media- infectionsof the ear
  • Meningitis: systemic infection which crosses the bbb
    case fatality rate of 30 %
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11
Q

Strep pneumo can alter vascular permeability to allow access to blood stream leading to bacteriemia. Can then directly invade endothelial cells. Cross the blood brain barrier by binding to cerebral capillaries, then transmigrate and enter CSF leading to meningitis

A

ok…KNOW

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12
Q

Strep pneumo virulence factors

A
  • Capsule- interferes with phagocytosis by leukocytes. Interferes with binding of complement to cell surface
  • Pilli: The initial event in invasive pneococcus disease is the attachment of encapsulated pneumococci to epithelial cells in the URT.
  • Cell wall components-
  • Choline binding proteins: major pneumococcal adhesin. Intereacts with carbohydrates on the pulmonary epithelial surface. Important in crossing the blood brain barrier during development of meningitis
  • Hemolysins: cause lysis of host cells and activate complement
  • Hydrogen peroxide
  • Neuraminidase and IgA proteas: Importan tin invasion and destruction of secreted IgA at the mucosal surface.
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13
Q

Two vaccines for strep pneumo

A

1) Pneumovax: MULTIVALENT, NON-CONJUGATED, 23 capsule types, for older patients and high risk groups like: HIV, cardiopulmonary, transplant patients, splenic disorders.
Lasts 5-7 years
not effective in infants and young
Protects against invasive pneumococcal disease

2) Prevnar: Heptavalent, 13 groups, conjugated
safe but expensive. Good for infants

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14
Q

Neisseria morphology

A

gram negative, non-motile that occur in pairs (diplococci)

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15
Q

Many Neisseria are part of normal flora

A
  • Two pathogenic neisseria:
    Neisseria Gonorrhoea- high prevalence, low mortality
    Neisseria Meningitidis: cause of meningococcal meningitis and sepsis. Low prevalence but high mortality
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16
Q

So if someone is talking about meningococcus meningitis they are referring to what bacteria

A

Neisseria meningitidis

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17
Q

N. Meningitidis has a prominent antiphagocytic polysaccharide capsule. This differentiates it from N Gonorrhaea

A

KNOW

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18
Q

What Neisseria meningitidis subgroups cause sporadic (small) outbreaks

A

B,C,Y

N.M is grouped on the basis of their capsular polysaccharide into 12 serogroups. Those associated with disease are
A, B, C, Y W125

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19
Q

Epidemic neisseria meningitidis?

A

Serotype A

20
Q

Meningitis belt

A

sub-saharan africa

  • epidemics occur every 5-12 years, last for 2-3 dry seasons and die out during intervening rainy season
21
Q

Pathogeneisis of fulminant meningitis from neisseria

A

Begins abruptly with sudden high fever, stiff neck, chills, myalgias, weakness, NAUSEA, VOMITTING, and headache. Aprehension, restlessness, delirium. Widespread petechial and skin lesions appear suddenly.

Pulmonanry insufficiency then develops and patients will die

22
Q

Major toxin of N Meningitidis=

A

lipooligosaccharide- endotoxin (elicit strong immune response)

the antiphagocytic capsule is also important

23
Q

Only known reservoir of N meningitidis

A

human nasopharynx…spread via respiratory droplets. Aspiration of the infective particles

24
Q

Meningococci attach to the nonciliated columnar epithelium of the nasopharynx. Attachment is mediated by pili and possibly other outer membrane components. Invasion of the mucosal cells occurs by a mechanism that involves phase variation (turning off capsule genes then turning them back on once they get in the bloodstream.

A

KNOW

25
Q

DOC for meningococcemia

A

Penicillin

26
Q

Menomune

A

N menigitidis vaccine against serogroups A, C, Y, W135

  • Unconjugated so there is no memory cmponent
  • given to high risk and military
  • controls epidemics
27
Q

Menactra

A

Vaccine for serogroups A, C, Y, W135
licensed for use in 11-55 yo
Conjugate so there is memory
Given to all children 11-12 yo

28
Q

Neither vaccine covers what serogroup?

A

B

29
Q

High frequency genetic variation of N meningitidis?

A

Phase variation: changes in expression of a gene leading to on-off control. Remember slip/strand misparing. Many systems employ phase variation

Antigenic Variation: Changes in genes leading to expression of different forms of similar genes. Often involves the pili

30
Q

Review phase variation slide 26

A

ok

31
Q

H influenza

A

major agent of otitis media, resp disease, and meningitis in YOUNG children

32
Q

H influ meningitis cases peak at what age group

A

6 months of age

33
Q

H. Influ isolates classified according to

A

capsule polysaccharides

34
Q

Most important H Influ pathogenic serotype

A

serotype B

35
Q

Chief H flu virulence factor?

A

capsule

36
Q

Chief H flu vaccine

A

Hib- type B capsular polysaccharide conjugated to a carrier protein. Given to kids between 2 and 15 months

37
Q

Look at Listeria

A

ok

38
Q

Bacterial meningitis causes in birth to 3 mths age group

A
  • Group B
  • Gram negative
  • Listeria

So Group B strep and listeria can affect the very young

39
Q

3 months to 2 years

A

strep pneumo
neisseria
H flu

40
Q

2 yrs to 18 yrs

A

Neisseria and Strep pneumo

41
Q

Most common cause of bacterial meningitis in an immunocompromised host?

A

staph
gram negative
pseudomonas

42
Q

Listeria monocytogenes

A

gram positive rod

  • a facultative intracellular parasite
  • causes listeriosis, mostly just a flu like condition
43
Q

Listeria causes meningitis in who

A

immune-comprimised adults, pregnant women and infants

Estimated incidence of listeriosis in aids pts is 300 times the incidence in the general population

44
Q

Intrauterine listeria infection often

A

kills the fetus

45
Q

Human reservoir of listeria monocytogenes

A

intestines

46
Q

food borne transmission associated with dairy products, meat, raw veggies

A

ok

47
Q

L monocytogenes attaches to and invades host cells like epithelial cells and macrophages via:

A

internalin protein

binds E cadherin on the cell surface

Cell to cell spread to avoid humoral immune system

Neurology (38 decks)

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