Microbial Mechanisms of Pathogenicity Flashcards

1
Q

Define pathogens

A

Disease causing microorganism

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2
Q

Define pathogenicity

A

ability to cause disease

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3
Q

Define virulence

A

degree of pathogenicity

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4
Q

Define infection

A

when body is invaded by a harmful microorganism

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5
Q

Define disease

A

when the health of the human body is affected by an infection

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6
Q

What are 3 portals of entry

A

1) mucous membrane
2) skin
3) parenteral route

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7
Q

What us the easiest and most common entry

A

respiratory tract ( mucous membrane)

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8
Q

Define ID50

A

infectious dose for 50% of a sample population

measures virulence of a microbes

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9
Q

Define LD50

A

lethal dose for 50% of a sample population

measures potency of a toxin

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10
Q

What are 2 ways of adherence of microorganisms to Host cells

A

1) Surface molecules on the pathogens

2) bind to complementary surface receptors of host cell

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11
Q

Describe surface molecules on the pathogens

A

adhesins or ligands
located on glycocalyx or fimbraie or pili
glycoproteins or lipoproteins

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12
Q

Define bind to compementary surface receptors of host cell

A

mannose-sugar

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13
Q

What are 4 ways pathogens pentrate host defenses

A

1) capsules
2) cell wall components
3) enzymes
4) antigenic variation

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14
Q

Describe capsules as a way to penetrate host defenses

A

glycocalyx around the cell wall
impair phagocytosis ( streptococcus pneumoniae, haemophilus influenza,bacillus anthracis)
have capsule increased virulence
body can create antibodies against capsules

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15
Q

Describe cell wall components to penetrate host defenses

A

1) M protein resists phagocytosis
2) Opa protein
3) waxy lipid ( mycolic acid) resists digestion

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16
Q

Describe how M protein resists phagocytosis

A

streptococcus pyogenes

produce heat resistence and resistent proteins

17
Q

Describe Opa protein as away to penetrates host defenses

A

Neisseria gohorrhoeae
attach to host cell
use fimbrae and outer membrane protein
inhibit T helper cell

18
Q

Describe waxy lipid as a wayof penetrating host defenses

A

resists digestion
ex: mycobacterium tuberculosis
has ability to divide in microphage

19
Q

What are 5 enzymes used to penetrate host defenses

A

1) Coagulases
2) Kinases
3) Hyaluronidase
4) Collagenase
5) IgA proteases

20
Q

Describe the enzyme coagulases

A

coagulate fibrinogen
helps with formation of clot. so when infection bacteria form a blood clot,form a wall, and prevent bloodflow to infection site so immune system cells can’t get to site
ex. staphylococcus

21
Q

Describe kinases as a way to penetrate host defenses

A

digest fibrin clots
bacteria will destroy the clotthat host body creates to defend itself so that infection can spread
ex. streptococcous

22
Q

Describe hyaluronidase as a way to penetrate host defenses

A

digests polysaccharides that hold cells together
produced by streptococcus
ex.gasgrene

23
Q

Describe collagenase as a enzyme to penetrate host defenses

A

breaks down collagen

24
Q

Describe IgA proteases as a way to penetrate host defenses

A

destroy IgA antibodies

25
Describe antigenic variation as a way of penetrate hoat defenses
pathogens alter their surface antigens evade destruction by host antibodies ex. neisseria,influenza virus
26
Describe invasins as a way to penetrate into host cell cytoskeleton
surface proteins produced by bacteria rearrange actin filaments of the cytoskeleton cause membrane ruffling ex. salmonella typhi use actin to move from 1 cell to the next ( shigella and listeria)
27
What are 3 ways that bacterial pathogens damage host cells
1) by using the host's nutrients 2) direct damage 3) production of toxins
28
How do using host's nutrients a way bacterial pathogens damage host cells ( example of one way is the answer)
siderophores-proteins secreted by pathogens binds iron more tightly than host cells siderophores has higher affinity for iron then hemoglobin
29
Describe 4 direct damage as a bacterial pathogens damage host cell
disrupts host cell function uses host cell nutrients produces waste products multiples in host cells and cause ruptures
30
Define toxins
poisonous substance produced by microorganisms | produce fever,cardiovascular problem,diarrhea,shock
31
Define toxigenicity
ability of a microorganism to produce a toxin
32
Describe toxemia
presence of toxin in the host's blood
33
What are the 2 types of toxins
exotoxins | endotoxins
34
Describe exotoxins
proteins produced and secreted by bacteria soluble in body fluids,destroy host cells and inhibit metabolic functions ex. hemolysins ( released by beta hemolytic streptococci) ex. botulinum toxin ( neurotoxin, release by clostridium botulinum) ex. tetanus toxin ( neurotoxin) released by clostridium tetanu
35
``` Exotoxins Sources? Relation to microbe? Chemistry? Fever? Neutralized by antitoxin? LD50 ```
``` mostly gram + by-products of growing cell protein no yes small ```
36
Describe enterotoxins
exotoxins whose activity affects the small intestine cause are massive secretion of fluid into intestinal lumen and vomiting and diarrhea ex. vibrio enterotoxin and shiga toxin
37
Describe endotoxins bacteria type? 2 examples of bacteria that have this toxin?
Lipid A portion of lipopolysaccharides ( LPS) OF GRAM NEGATIVE BACTERIA released when the bacteria die ex. salmonella typhi and proteus vulgaris
38
``` Endotoxin Source relation to microbes chemistry fever neutralized by antitoxin ld50 ```
``` gram - outer membrane lipid A yes no relatively large ```
39
Describe 5 portals of exit
1) Respiratory tract 2) gastrointestinal tract 3) genitourinary tract 4) skin 5) blood