Bacteria and Disease

Question 1

what is the LD50

Answer 1

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

Question 2

give some examples of virulence factors

Answer 2

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

Question 3

what type of hosts to opportunistic pathogens infect

Answer 3

compromised hosts

Question 4

what proteins make up flagella

Answer 4

flagellins

Question 5

what are adhesins + what are they made of

Answer 5

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

Question 6

what is a biofilm

Answer 6

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

Question 7

what is tissue specificity in bacteria

Answer 7

the bac is specific to which tissue it binds

Question 8

what are invasins

Answer 8

molecules which mediate the invasion of host cells

Question 9

what is hyaluronidase

Answer 9

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

Question 10

what is collagenase

Answer 10

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

Question 11

define bacteraemia

Answer 11

presence of bacteria in blood stream

Question 12

define septicaemia

Answer 12

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

Question 13

explain the function of coagulase in relation to bacteria

Answer 13

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

Question 14

how do bac get into host cells

Answer 14

phagocytosis or forcing a non phagocyte into engulfing them

Question 15

how does salmonella force its way into human cells

Answer 15

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

Question 16

which nutrient is most needed by bacteria

Answer 16

iron

Question 17

write a quick note on endotoxins

Answer 17

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

Question 18

LPS is a pyrogen what does this mean

Answer 18

triggers the immune sys inflammatory response

Question 19

how is testing for endotoxin contamination carried out

Answer 19

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

Question 20

what are AB toxins comprised

Answer 20

Active A domain and binding B domain

Question 21

what does diphtheria exotoxin do

Answer 21

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

Question 22

what does botulinum toxin do

Answer 22

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

Question 23

what does tetanus toxin do

Answer 23

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

Question 24

what does cholera toxin do

Answer 24

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

Question 25

cytolytic toxins

Answer 25

degrade cytoplasmic membrane integrity -> lysis and death.

Question 26

what are haemolysins

Answer 26

toxins that lyse red blood cells

Question 27

what do superantigens do

Answer 27

cause nonspecific overstimulation of imune cells. overproduction of cytokines causing inflammatory response. may lead to high fevers, low bp, organ failure, shock and death

Question 28

what is attenuation

Answer 28

where pathogens lose their virulence

Question 29

what benefit have attenuated viruses got for society

Answer 29

they can be used as vaccines i.,e TB