10. Bacterial colonisation

Question 1

mutualism

Answer 1

both parties benefit

Question 2

mutualism example

Answer 2

gut bacteria breaking down nutrients

Question 3

commensalism

Answer 3

one party benefits the other is neutrally effected

Question 4

commensalism example

Answer 4

skin flora

Question 5

parasitism

Answer 5

one party benefits the other is harmed

Question 6

parasitism example

Answer 6

bacterial pathogens

Question 7

what are the 3 relationships between bacteria and humans?

Answer 7

mutualism, commensalism and parasitism

Question 8

what steps are essential for colonisation?

Answer 8

adhesion
local spread
growth
evasion of host defences
exit from host - transmission
damage to host

Question 9

what are the colonisation steps unique to pathogens?

Answer 9

damage to host

Question 10

how are capsules used for adhesion?

Answer 10

sticky so stick to the host cell

Question 11

how are slime layers used for adhesion?

Answer 11

sticking

Question 12

how are flagella used for adhesion?

Answer 12

to drive deeper into tissues and through mucus layers

Question 13

how are pili/fimbriae used for adhesion?

Answer 13

get through mucus layers
no gram -ve and +ve

Question 14

how are lipoteichoic acids and carbohydrates used for adhesion?

Answer 14

attach to cell host cells

Question 15

how are bacterial outer membrane proteins used for adhesion?

Answer 15

stick to ECM protein like fibronectin and fibrinogen

Question 16

what do bacteria bind to on host cells?

Answer 16

surface receptors
ECM proteins
secreted proteins and carbohydrates
calcified components
implants and prostheses

Question 17

Why are epithelial cells a big target for bacteria?

Answer 17

Because of the massive mucosal epithelium surface area

Question 18

why are fibroblasts targetted by bacteria?

Answer 18

they are in the sub dermal layer and help with wound healing and tissue repair

Question 18

what are the cell types targetted by bacteria?

Answer 18

epithelial cells
fibroblasts
phagocytic cells
Endothelial cells

Question 18

why are phagocytic cells targetted by bacteria?

Answer 18

to disrupt their function to continue disease progression

Question 19

why are endothelial cells targetted by bacteria?

Answer 19

target blood vessels for distribution and sepsis

Question 19

how do humans Initially defend against bacteria?

Answer 19

lysozymes in the saliva
mucus to wash away pathogens
acidic environments like the stomach

Question 20

what causes the most pain in a bacterial infection?

Answer 20

the inflammation response of the immune system

Question 21

where can you get gonorrhoea?

Answer 21

sexual organs
throat
blood stream
skin

Question 22

what can gonorrhoea cause?

Answer 22

Infertility arthritis Proctitis

Question 23

why are cases of gonorrhoea rising?

Answer 23

very drug resistant and super gonorrhoea cannot be treated Development of HIV prophylactic treatment means people are being less careful about other STIs

Question 24

stages of gonococcal infections

Answer 24

1. Initial exposure at the epithelium 2. at the basal surface and interact with macrophages 3. activation of pro-inflammatory cytokines leading to chronic inflammation 4. Tissue damage 5. cell damage - dead and dying epithelium and neutrophilsh

Question 25

what are the pro inflammatory cytokines?

Answer 25

TNFa and IFNy

Question 26

what percentage of gonorrhoea cases can be asymptomatic?

Answer 26

10-30%

Question 27

what virulence factors are involved in gonorrhoea pathogenesis?

Answer 27

Pili binding to integrins and possibly CD46 Opa porins - beta barrels LPS bind to glycoprotein receptors and complement and cause inflammation

Question 28

what is different about enteric bacteria LPS?

Answer 28

no O-antigen repeats but shorter oligosaccharide region

Question 29

what is the toxic part of LPS?

Answer 29

aceylated lipid A

Question 30

how do you get diversity in LPS?

Answer 30

phase variation of LPS upto 14 types of different LPS

Question 31

why do bacteria express lactoneotetraose?

Answer 31

to mimic host cells and avoid the immune system

Question 32

what does siayl transferase do ?

Answer 32

transfers sialic acid from host membranes to the bacteria and add to lactoneotetraose?

Question 33

when is siayl transferase expressed?

Answer 33

when the lactoneotetraose is present in the membrane

Question 34

what are the complement inhibitor points?

Answer 34

C4b binding protein Factor H Vitronectin

Question 35

what is the function of complement inhibitors?

Answer 35

they protect the host by preventing membrane attack complexes binding to host cells

Question 36

how have bacteria like gonorrhoea evolved to use complement inhibitors?

Answer 36

they bind the inhibitors to protect themselves from the complement

Question 37

how does gonorrhoea bind factor H?

Answer 37

can express the galactose needed to bind host sialic acid so the body thinks it is a host cell this means factor H will bind to it and prevent membrane attack complexes forming on the gonorrhoea bacteria

Question 38

what is unstable resistance?

Answer 38

resistance that can be phased on or off depending on the presence of a variable like galactose

Question 39

what porins do gonorrhoea produce?

Answer 39

Por1A and Por1B trimeric outer membrane proteins

Question 40

what is the function of porins in gonorrhoea?

Answer 40

nutrient uptake and invasion

Question 41

how do porins cause apoptosis?

Answer 41

translocation from bacterial membrane to mitochondrial membrane activating the intrinsic apoptosis pathway

Question 42

what is a positive about the porins?

Answer 42

it is a potential target for vaccines

Question 43

how do the porins contribute to host mimicry?

Answer 43

Factor H can bind the porins preventing complement activation and no membrane attack complex formation

Question 44

what is stable resistance?

Answer 44

the resistance is dependant is something that is nearly always expressed

Question 45

what else binds to gonorrhoea porins to prevent classical activation of the complement?

Answer 45

Por1A and Por1B can bind C4 binding protein preventing membrane attack complex formation

Question 46

what is a trade off for this resistance?

Answer 46

sialic acid coats bacteria in negative charge which can repel nutrients and other useful molecules cannot bind Opa

Question 47

what are sialic acid binding lectins?

Answer 47

often on immune cells interactions can subvert neutrophil functions

Question 48

what are the roles of LPS?

Answer 48

target receptors damage to host - lipid A toxin immune evasion - factor H