Microbiology: Overcome host' defences

Question 1

List the different surface structures which are used to fool or overcome host defence

Accepted Answer

Surface structures used to fool or overcome host defence
-Stealth
hide in a site which does have much contact with the immune system sequestration eg. the eye
hide within an intracellular location
cover oneself with poor ag
mimic surface structure of host cell
-surface ag variation
change their surface proteins or carbs= angelic variation b4 immune-mediated destruction occurs
-subversion of host’s defence
several surface structure are involved in this

Question 2

How do bacteria survive within intracellular environment

Accepted Answer

Bacteria which survive within intracellular environment allow themselves to be phagocytosed but they survive and thrive
they do this by using 1 or more of the following
-don’t activate the macrophage
-inhibiting phagosome- lysosome fusion
-resist destruction in the phagosome via murrain in the outer cell membrane
-escape using porins from phagosome

Question 3

Describe how bacteria spread from their site of invasion to the rest of the body

Accepted Answer

how bacteria spread from their site of invasion to the rest of the bodydirect spread of bacteria-bacteria invading from the outside often spread by extension

Question 4

Lymphogenous spread

Accepted Answer

Lymphogenous spreadlymph nodes trap bacteria closets to some of bacterial entry, if they are not success in trapping the pathogen they will spread along the lymphatics and will go into the heart and then the blood stream.If this is occurring the superficial lymph nodes should be checked to see if they are swollen

Question 5

For Haematgoenous list the 2 ways which bacteria spread through out the blood and which animals this will effect the mostcommon sites of organ localisations

Accepted Answer

Haematgoenous spreadmany bacteria enter the blood stream from any point (respiratory system) causing bacteraemia and their their toxins are present this will cause septicaemia.This usually occurs in younger animals because their immune system isn fully developed yetsome bacteria enters from the lymphatics for a localised site like the skin and then enter the blood stream via the thoracic duct and spread via the bloodstream, these animals are oldercommon sties of organ localisation include the joints (when many are affected), brain, meninges and kidneys

Question 6

List way in which a pathogenic bacteria causes damage to tissues or physiological process with the body

Accepted Answer

how bacteria causes destructiondirect destruction of cellsdestruction of cells or disruption of physiological processesinduce a tissue destructive inflammatory response or immune mediated tissue destruction

Question 7

List the steps of direct destruction of cells

Accepted Answer

direct destruction of cellsspore will be phagocytosed, so the bacteria gets inside-> the acidic environment stimulates the bacteria to become a larger metabolically active reticulate body, so it changes its shape-> using the hosts’ ATP the bacteria will divide and proven the cell (macrophage) from kill itself-> in response to inferon gamma the reticulate bodies go tint a dominant phase-> at the end of the replicative cycle a large no. of bodies (non active) are formed-> cell can be induced to undergo apoptosis-> the cell will either rupture or being dead there will be a release of initial bodies, thus making them infectious.

Question 8

For exotoxin what produces it level of toxicity level of specificity and mode of action level of ag what inactivates it?-location in bacterium composition and structure

Accepted Answer

exotoxin- produced by gram +ve and -ve by either excretion or lysis
usually potent toxins (only need a small amount to kill the host)
specific action mode of action is similar to enzymes
potent ag
heat activated and inactive by formalin to produce toxoids
location in bacterium outer membrane
-composition and structure; protein

Question 9

For Endotoxin state what produces it level of toxicity level of specificity and what does it stimulates?-type of ag -what destroys it -location in bacterium -composition and structure

Accepted Answer

Endotoxinproduced by gram -ve bacteria on bacterial lysis-less toxic than exotoxin (require a larger amount to do damage)-less specific than exotoxin and stimulates excessive inflammatory response @ high conc.-weak ag-heat stable but destroyed by oxidising agentslocation in bacterium withincomposition and structure; lipids and carbons

Question 10

Define septicaemia

Accepted Answer

septicaemia;presence of bacteria and their products (endotoxin or exotoxin) in bloodstream its blood poisoning

Question 11

Define endotoxaemia

Accepted Answer

Endotoxaemiapresence of excessive amounts of bacteria lipopolysaccharides in the blood leading to a hyper-inflammatory disorderits a form of septicaemia but without the bacteria in the blood

Question 12

Explain the functions of the different structures of the endotoxin(the different part of lipopolysaccharides-core sugar-O ag-lipid A )

Accepted Answer

functions of the different structures of the endotoxin
LPS- lipopolysaccharides the components are
-core sugars; barrier to macromolecule
-“O” ag: adhere to cell surfaces, if long it will impedes (stop) destruction of bacteria by serum components and phagocytic cells by antigenic shifts
-lipid A; stimulates immune system resulting in a hyper-inflammatory response

Question 13

List the different sources of endotoxin

Accepted Answer

different sources of endotoxinGIT damage/diseaserespiratory tractperacute gram -ve mastitisother serious gram -ve infections

Term	Definition
List the different surface structures which are used to fool or overcome host defence	Surface structures used to fool or overcome host defence -Stealth hide in a site which does have much contact with the immune system sequestration eg. the eye hide within an intracellular location cover oneself with poor ag mimic surface structure of host cell -surface ag variation change their surface proteins or carbs= angelic variation b4 immune-mediated destruction occurs -subversion of host’s defence several surface structure are involved in this
How do bacteria survive within intracellular environment	Bacteria which survive within intracellular environment allow themselves to be phagocytosed but they survive and thrive they do this by using 1 or more of the following -don’t activate the macrophage -inhibiting phagosome- lysosome fusion -resist destruction in the phagosome via murrain in the outer cell membrane -escape using porins from phagosome
Describe how bacteria spread from their site of invasion to the rest of the body	how bacteria spread from their site of invasion to the rest of the body direct spread of bacteria -bacteria invading from the outside often spread by extension
Lymphogenous spread	Lymphogenous spread lymph nodes trap bacteria closets to some of bacterial entry, if they are not success in trapping the pathogen they will spread along the lymphatics and will go into the heart and then the blood stream. If this is occurring the superficial lymph nodes should be checked to see if they are swollen
For Haematgoenous list the 2 ways which bacteria spread through out the blood and which animals this will effect the most common sites of organ localisations	Haematgoenous spread many bacteria enter the blood stream from any point (respiratory system) causing bacteraemia and their their toxins are present this will cause septicaemia. This usually occurs in younger animals because their immune system isn fully developed yet some bacteria enters from the lymphatics for a localised site like the skin and then enter the blood stream via the thoracic duct and spread via the bloodstream, these animals are older common sties of organ localisation include the joints (when many are affected), brain, meninges and kidneys
List way in which a pathogenic bacteria causes damage to tissues or physiological process with the body	how bacteria causes destruction direct destruction of cells destruction of cells or disruption of physiological processes induce a tissue destructive inflammatory response or immune mediated tissue destruction
List the steps of direct destruction of cells	direct destruction of cells spore will be phagocytosed, so the bacteria gets inside -> the acidic environment stimulates the bacteria to become a larger metabolically active reticulate body, so it changes its shape -> using the hosts’ ATP the bacteria will divide and proven the cell (macrophage) from kill itself -> in response to inferon gamma the reticulate bodies go tint a dominant phase -> at the end of the replicative cycle a large no. of bodies (non active) are formed -> cell can be induced to undergo apoptosis -> the cell will either rupture or being dead there will be a release of initial bodies, thus making them infectious.
For exotoxin what produces it level of toxicity level of specificity and mode of action level of ag what inactivates it? -location in bacterium composition and structure	exotoxin- produced by gram +ve and -ve by either excretion or lysis usually potent toxins (only need a small amount to kill the host) specific action mode of action is similar to enzymes potent ag heat activated and inactive by formalin to produce toxoids location in bacterium outer membrane -composition and structure; protein
For Endotoxin state what produces it level of toxicity level of specificity and what does it stimulates? -type of ag -what destroys it -location in bacterium -composition and structure	Endotoxin produced by gram -ve bacteria on bacterial lysis -less toxic than exotoxin (require a larger amount to do damage) -less specific than exotoxin and stimulates excessive inflammatory response @ high conc. -weak ag -heat stable but destroyed by oxidising agents location in bacterium within composition and structure; lipids and carbons
Define septicaemia	septicaemia; presence of bacteria and their products (endotoxin or exotoxin) in bloodstream its blood poisoning
Define endotoxaemia	Endotoxaemia presence of excessive amounts of bacteria lipopolysaccharides in the blood leading to a hyper-inflammatory disorder its a form of septicaemia but without the bacteria in the blood
Explain the functions of the different structures of the endotoxin (the different part of lipopolysaccharides -core sugar -O ag -lipid A )	functions of the different structures of the endotoxin LPS- lipopolysaccharides the components are -core sugars; barrier to macromolecule -“O” ag: adhere to cell surfaces, if long it will impedes (stop) destruction of bacteria by serum components and phagocytic cells by antigenic shifts -lipid A; stimulates immune system resulting in a hyper-inflammatory response
List the different sources of endotoxin	different sources of endotoxin GIT damage/disease respiratory tract peracute gram -ve mastitis other serious gram -ve infections

Microbiology: Overcome host' defences

List the different surface structures which are used to fool or overcome host defence

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