Bacteria and Disease Flashcards
what is the LD50
lethal dose 50 = the amount of agent that kills 50% if the animals in a test group
give some examples of virulence factors
adherence to host cells, invasiveness, nutrient aquisistion, immune evasion, antibiotic resistance, superantigens
what type of hosts to opportunistic pathogens infect
compromised hosts
what proteins make up flagella
flagellins
what are adhesins + what are they made of
receptors on bacteria which help adhesion. they are made of glycoproteins or lipoproteins
what is a biofilm
a community of microbes which are really resistant to the immune system
what is tissue specificity in bacteria
the bac is specific to which tissue it binds
what are invasins
molecules which mediate the invasion of host cells
what is hyaluronidase
an enzyme which breaks down hyaluronic acid which is a key factor in keeping cells together which enables bac to invade deeper into tissues
what is collagenase
breaks down collagen that surrounds endothelial cells allowing bac to enter bloodstream
define bacteraemia
presence of bacteria in blood stream
define septicaemia
bloodborne systemic infection -> may lead to massive inflammation, septic shock and death
explain the function of coagulase in relation to bacteria
bacteria can produce the enzyme to accelerate the formation of blood clot, which they can then invade and protect themselves from immune system
how do bac get into host cells
phagocytosis or forcing a non phagocyte into engulfing them
how does salmonella force its way into human cells
uses needle-like structure to inject proteins into host cell + causes the cell to uptake it where it proliferates inside a vacuole
which nutrient is most needed by bacteria
iron
write a quick note on endotoxins
in Gram - bac. Lipid A responsible for toxin properties- only pathogenic bacteria have a toxic LPS
LPS is a pyrogen what does this mean
triggers the immune sys inflammatory response
how is testing for endotoxin contamination carried out
using limulus amebocyte lysate- amebocytes are found in blood of horseshoe crab. amebocytes lyse in presene of endotoxin to create a clot
what are AB toxins comprised
Active A domain and binding B domain
what does diphtheria exotoxin do
blocks protein synthesis by adding an ADP-ribosyl group to EF-TU which prevents translation
what does botulinum toxin do
it is a neurological exotoxin produced by clostridium botulinum - one of most potent biological toxins known. 4g to kill 8b people. causes flaccid paralysis
what does tetanus toxin do
neurological exotoxin produced by clostridium tetani. causes involuntary contraction of muscles
what does cholera toxin do
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
cytolytic toxins
degrade cytoplasmic membrane integrity -> lysis and death.
what are haemolysins
toxins that lyse red blood cells
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
what is attenuation
where pathogens lose their virulence
what benefit have attenuated viruses got for society
they can be used as vaccines i.,e TB
