Bacteria and Disease Flashcards

1
Q

what is the LD50

A

lethal dose 50 = the amount of agent that kills 50% if the animals in a test group

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2
Q

give some examples of virulence factors

A

adherence to host cells, invasiveness, nutrient aquisistion, immune evasion, antibiotic resistance, superantigens

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3
Q

what type of hosts to opportunistic pathogens infect

A

compromised hosts

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4
Q

what proteins make up flagella

A

flagellins

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5
Q

what are adhesins + what are they made of

A

receptors on bacteria which help adhesion. they are made of glycoproteins or lipoproteins

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6
Q

what is a biofilm

A

a community of microbes which are really resistant to the immune system

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7
Q

what is tissue specificity in bacteria

A

the bac is specific to which tissue it binds

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8
Q

what are invasins

A

molecules which mediate the invasion of host cells

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9
Q

what is hyaluronidase

A

an enzyme which breaks down hyaluronic acid which is a key factor in keeping cells together which enables bac to invade deeper into tissues

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10
Q

what is collagenase

A

breaks down collagen that surrounds endothelial cells allowing bac to enter bloodstream

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11
Q

define bacteraemia

A

presence of bacteria in blood stream

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12
Q

define septicaemia

A

bloodborne systemic infection -> may lead to massive inflammation, septic shock and death

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13
Q

explain the function of coagulase in relation to bacteria

A

bacteria can produce the enzyme to accelerate the formation of blood clot, which they can then invade and protect themselves from immune system

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14
Q

how do bac get into host cells

A

phagocytosis or forcing a non phagocyte into engulfing them

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15
Q

how does salmonella force its way into human cells

A

uses needle-like structure to inject proteins into host cell + causes the cell to uptake it where it proliferates inside a vacuole

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16
Q

which nutrient is most needed by bacteria

17
Q

write a quick note on endotoxins

A

in Gram - bac. Lipid A responsible for toxin properties- only pathogenic bacteria have a toxic LPS

18
Q

LPS is a pyrogen what does this mean

A

triggers the immune sys inflammatory response

19
Q

how is testing for endotoxin contamination carried out

A

using limulus amebocyte lysate- amebocytes are found in blood of horseshoe crab. amebocytes lyse in presene of endotoxin to create a clot

20
Q

what are AB toxins comprised

A

Active A domain and binding B domain

21
Q

what does diphtheria exotoxin do

A

blocks protein synthesis by adding an ADP-ribosyl group to EF-TU which prevents translation

22
Q

what does botulinum toxin do

A

it is a neurological exotoxin produced by clostridium botulinum - one of most potent biological toxins known. 4g to kill 8b people. causes flaccid paralysis

23
Q

what does tetanus toxin do

A

neurological exotoxin produced by clostridium tetani. causes involuntary contraction of muscles

24
Q

what does cholera toxin do

A

produced by vibrio cholera. it is an enterotoxin meaning it affects the small intestine. causes secretion of fluid into the intestinal lumen causing vomiting and diarrhea

25
cytolytic toxins
degrade cytoplasmic membrane integrity -> lysis and death.
26
what are haemolysins
toxins that lyse red blood cells
27
what do superantigens do
cause nonspecific overstimulation of imune cells. overproduction of cytokines causing inflammatory response. may lead to high fevers, low bp, organ failure, shock and death
28
what is attenuation
where pathogens lose their virulence
29
what benefit have attenuated viruses got for society
they can be used as vaccines i.,e TB
30