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BI374 Final > Host-microbiota: pathogenesis > Flashcards

Host-microbiota: pathogenesis Flashcards

1
Q

what do pathogenic microorganisms have to do?

A
  • establish entry, colonization and growth in the host
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2
Q

What must be expressed to cause change in host function (disease)

A
  • virulence
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3
Q

What 2 factors allow entry of a pathogen?

A
  • adhesion factors
  • invasiveness
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4
Q

What are the adhesion factors?

A
  • tissue specificity (ex. ciliated cells - bordetella)
  • host specificity (ex. neisseria gonorrhoea - urogenital tissue)
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5
Q

What less specific cellular components aid in adhesion?

A
  • capsule
  • slime layer
  • pili
  • colonization factor antigens (CFA)
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6
Q

What do pathogens have to attach to?

A
  • mucosal material
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7
Q

What factors contribute to invasiveness?

A
  • penetrate epithelium
  • may possess enzymes that aid in mucosal penetration
  • need to establish certain point of occupancy
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8
Q

What happens once a microorganism is able to multiply at an invasion site?

A
  • colonization and growth occur
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9
Q

What must microorganisms do to grow?

A
  • sequester necessary nutrients and cofactors
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10
Q

What is bacteremia?

A
  • bacteria in bloodstream
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11
Q

What must happen if bacteria is not host-adapted?

A
  • must scavange
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12
Q

What factors contribute to virulence?

A
  • characteristics that aid in establishment and maintenance of disease (enzymes or toxins)
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13
Q

WHat is hyaluronidase?

A
  • breaks down hyaluronic acid (tissue cement) in host
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14
Q

What are proteases? Give an example

A
  • breakdown/depolymerize host proteins (ex. salmonella)
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15
Q

What are nucleases?

A
  • breakdown nucleotides
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16
Q

What is actin filament depolymerization?

A
  • penetration past mucosal barrier
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17
Q

What are lipases?

A
  • breakdown fats, can escape defences and enter other parts of body
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18
Q

What is collagenase? Give an example

A
  • breakdown collagen/connective tissue (ex. clostridium kills tissue)
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19
Q

What are fibrinolytic enzymes?

A
  • break through scabs (ex. streptokinase)
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20
Q

What are the advantageous properties of fibrinolytic enzymes?

A
  • clots/wall/isolate scabs and protect from potential invaders
21
Q

What are coagulases?

A
  • cause clotting
22
Q

What are the advantageous properties of coagulase enzymes for bacteria?

A
  • can wall bacteria off and protect them from immune cells - local infection
23
Q

What are the 2 types of toxins?

A
  • endotoxins
  • exotoxins
24
Q

What is an endotoxin?

A
  • cell-bound and released in large amounts when cell lyses
  • gram neg made of lipopolysaccharide material
25
Q

Give an example of an endotoxin

A
  • nisseria meningitidis
  • grows abnormally, sheds endotoxic material
26
Q

What is an exotoxin?

A
  • protein released extracellularly as organism grows
  • gram pos
  • skips establishment in host, short incubation
27
Q

Give an example of an exotoxin

A
  • clostridia
28
Q

what are the 3 general categories of endotoxins?

A
  • cytolytic toxins
  • A-B toxins
  • superantigen toxins
29
Q

What are cytolytic toxins? Give an example

A
  • enzymatically attack cell constituents and cause disruption (attack enzymes needed to acquire nutrition)
  • ex. phospholipids
30
Q

What are A-B toxins?

A
  • consist of 2 covalently bound subunits :B binds to host receptor, allows translocation of A (active portion) and elicits toxicity
31
Q

What are superantigen toxins?

A
  • stimulate large numbers of immune response cells which result in massive inflammatory reactions (kills own cells)
32
Q

What is diphtheria toxin? what is it produced by?

A
  • A-B toxin
  • iron concentration in environment plays a role in production by corynebacterium diphtheriae
33
Q

What is botulinum toxin?

A
  • A-B toxin
  • clostridium botulinum
34
Q

When is botulinum produced?

A
  • when organism is growing in preserved food product (not human host)
35
Q

What is tetanus?

A
  • A-B toxin
  • C. tetani
36
Q

What does tetanus result from?

A
  • results from deeper penetration of C. tetani where conditions are more anoxic
37
Q

What is death from tetanus a result of?

A
  • severe neurological impairment
38
Q

What is pseudomembranous?

A
  • dense material of bacteria/defence cells that plug airway
39
Q

What are enterotoxins?

A
  • exotoxins that act on GI tract
  • A-B toxin by vibrio cholerae
40
Q

What is pseudomembranous?

A
  • dense material of bacteria/defence cells that plug airway
41
Q

What symptoms do enterotoxins cause?

A
  • fluid in intestinal lumen = diarrhea
42
Q

What happens when there is an osmotic imbalance?

A
  • transmission of electrolytes and water is sent to gain balance on ion dump
43
Q

What enteropathogenic bacteria produce toxins with similar modes of action to cholera toxin?

A
  • salmonella and E. coli
44
Q

What symptoms do endotoxins cause?

A
  • fever from production of endogenous pyrogens by the host
45
Q

What is pyrogen?

A
  • activation of control centre of host
46
Q

General endotoxin toxicity is ____ than exotoxins

A
  • lower
47
Q

What assay is highly sensitive for endotoxins?

A
  • limulus test
48
Q

What are virulence factors?

A
  • structures/substances exported to bacterial cell surface or out of the cell
  • anything that aids infection process/contributes to symptoms of disease
49
Q

State and describe 5 factors/components associated with a bacterial cell that might support or contribute to its virulence

A
  • They contain enterotoxins that act on the GI tract and cause massive secretion of fluid into the intestinal fluid
  • Their flagellum allow for motility, H-antigen allows for adherence
  • O antigens inhibit their demise in a phagocytic cell
  • Their capsule is protective and antigen inhibits complement binding
  • Their siderophores allow for iron uptake and nutrients

BI374 Final (12 decks)

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