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ABS > Micro 3- pathogenesis > Flashcards

Micro 3- pathogenesis Flashcards

1
Q

pathogenicity

A

the ability to cause disease

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2
Q

virulence

A

the degree of pathogenicity

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3
Q

portals of entry

A

-mucous membranes
-skin
-parenteral route- deposited directly into tissues when barriers are penetrated
(most pathogens have a preferred portal of entry)

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4
Q

ID50

A

infectious dose for 50% of a sample population

-measures virulence of a microbe

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5
Q

LD50

A

lethal dose for 50% of a sample population

-measures potency of a toxin

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6
Q

almost all pathogens attach to host tissues in a process called

A

adherence (adhesion)

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7
Q

adhesins (ligands) on the pathogen do what

A

they bind to receptors on the host cells

  • glycocalyx
  • fimbriae
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8
Q

microbes form

A

biofilms

which allows for adherence of one microbe to the next

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9
Q

list of how pathogens penetrate host defenses

A
  • capsules
  • enzymes
  • cell wall components
  • antigenic variation
  • penetration into host cell cytoskeleton
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10
Q

how pathogens penetrate host defenses:

capsules

A
  • glycocalyx around the cell wall
  • impair phagocytosis
    ex: streptococcus pneumoniae- pnemonia, haemophilus influenzae- pneumonia and meningitis, bacillus anthracis-anthrax, yersinia pestis- plague
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11
Q

how pathogens penetrate host defenses:

enzymes -list

A
  • coagulases
  • kinases
  • hyaluronidase
  • collagenase
  • IgA proteases
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12
Q

enzyme:

coagulases

A

coagulate fibrinogen

-form “wall” blood clot, fibrinogen precursors for blood clot

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13
Q

enzyme:

kinases

A

digest fibrin clots

(fibrin -> fibrinogen), from host mechanism

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14
Q

enzyme:

hyaluronidase

A

digest polysaccharides that hold cells together

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15
Q

enzyme:

collagenase

A

breaks down collagen

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16
Q

enzyme:

IgA proteases

A

destroy IgA antibodies

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17
Q

how pathogens penetrate host defenses:
cell wall components:
M protein

A

resists phagocytosis

-streptococcus pyogenes

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18
Q

how pathogens penetrate host defenses:
cell wall components:
Opa

A

protein allows attachment to host cells

-neisseria honorrhoeae

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19
Q

how pathogens penetrate host defenses:
cell wall components:
Waxy lipid

A

(mycelia acid) resists digestion

-mycobacterium tuberculosis

20
Q

how pathogens penetrate host defenses:

antigenic variation

A

pathogens alter their surface antigens (and antibodies are rendered ineffective)

21
Q

how pathogens penetrate host defenses:

penetration into host cell cytoskeleton

A

using invasins or using actin to move from one cell to the next
e.g. shigella and listeria

22
Q

invasins

A

surface proteins produced by bacteria that rearrange tin filamentous of the cytoskeleton (membrane ruffling)

23
Q

how can pathogens damage the host?

A
  • using host’s nutrients (siderophores)
  • direct damage
  • production of toxins
24
Q

damage to host:

using host’s nutrients: siderophores

A
  • iron is required for most pathogenic bacteria

- siderophores are proteins secreted by pathogens that bind iron more tightly than host cells (ex: enterobactin)

25
Q

toxins are

A

poisonous substances produced by microorganisms

-produce fever, cardiovascular problems, diarrhea, and shock

26
Q

toxigenicity is

A

the ability of a microorganism to produce a toxin

27
Q

toxemia

A

presence of toxin in the host’s blood

28
Q

intoxications

A

presence of toxin without microbial growth

29
Q

what are exotoxins?

A

proteins produced and secreted by bacteria

  • soluble in bodily fluids, destroy host cells and inhibit metabolic functions
  • gram positive
30
Q

antitoxins

A

antibodies against specific exotoxins

31
Q

toxoids

A

inactivated exotoxins used in vaccines

32
Q

list of types of exotoxins

A
  • AB toxins
  • membrane disrupting toxins
  • superantigens
33
Q

AB toxins

A

contain an enzyme component (A part) and a binding component (B part)
example: diphtheria toxin

34
Q

what do membrane disrupting toxins do? 3 types?

A

they lyse host cells by disrupting plasma membrane

  1. leukocidins
  2. hemolysins
  3. streptolysins
35
Q

leukocidins

membrane- disrupting toxins

A

kill phagocytic leukocytes

36
Q

hemolysins

membrane-disrupting toxins

A

kill erythrocytes by forming protein channels

37
Q

streptolysins

membrane- disrupting toxins

A

hemolysins produced by streptococci

38
Q

superantigens

A

cause an intense immune response due to the release of cytokines from host cells (T cells)
-cause symptoms of fever, nausea, vomiting, diarrhea, shock, and death

39
Q

what are genotoxins?

A

they are toxins that damage DNA (causing mutations, disrupting cell division, and leading to cancer)

40
Q

what are endotoxins and where do they come from

A

they are the lipid A portion of lipopolysaccharides (LPS) of gram negative bacteria that are released during bacterial multiplication and when gram negative bacteria die

41
Q

how do endotoxins work?

A

they stimulate macrophages to release cytokines and cause disseminated intravascular coagulation -> blood clotting in capillaries formed - decreased blood supply, can cause damage to cells and tissues

42
Q

exotoxins vs. endotoxins:

chemistry

A

exotoxins- proteins (usually with 2 parts- A and B)

endotoxins- lipid protein, lipid A of outer membrane LPS

43
Q

exotoxins vs. endotoxins:

toxicity (ability to cause disease)

A

exotoxins- high

endotoxins- low

44
Q

exotoxins vs. endotoxins:

bacterial source

A

exotoxins- mostly gram +

endotoxins- mostly gram -

45
Q

what is lysogenic conversion

A

changes characteristics of a microbe due to incorporation of a bacteriophage

46
Q

examples of bacteriophage genes:

A

diptheria toxin, botulinum neurotoxin and capsule produced by streptococcal pneumoniae

ABS (31 decks)

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