POM 10 - Activities of a pathogen 2 Flashcards

1
Q

what are the 4 components of virulence factors

A

adherence

invasion

immune evasion

toxins

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2
Q

what are virulence factors

A

the genetic determinants that allow a pathogen to cause disease

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3
Q

explain the virulence factor of adherence

A

ability to interact or bind with humor cell

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4
Q

explain the virulence factor of invasion

A

factors that enable bacteria to find a new niche

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5
Q

explain the virulence factor of immune evasion

A

avoidance of innate immune system

most important factor

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6
Q

explain the virulence factor of toxins

A

bacteria release to damage neighboring cells

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7
Q

what is the most important virulence factor

A

immuen evasion

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8
Q

what is virulence

A

the ability to cause disease in hosts with intact defences

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9
Q

what does virulence require

A

some breech of host defences

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10
Q

what is pyrogenic infection - what are the 3 parts to it

A

tissue invasion, multiplication, and immune response in sterile site

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11
Q

what is granulomatous/chronic infection - what part of the immune system does it evade and what cells are activated to respond to this infection

A

evade innate immune system

activated macrophages fuse and surround the antigen

incomplete host response = granuloma

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12
Q

what is bacterial intoxication

A

change in host physiology and tissue destruction

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13
Q

how does cholera cause an infection at a cellular level - 4 steps

A

infection with vibrio cholerae

cholera divides in bowel and releases a toxin which inhibits GTPase enzyme

cGMP builds up inside cell and causes cell membrane pump to pump Cl- ions out of cell

Cl- Na+ and water is lost in bowel = profuse diarrhoea

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14
Q

what happens at the start of appendicitis

A

appendix is obstructed with a faecolith

bacteria propogate

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15
Q

how does the bacteria affect the appendix in appendicitis at the cellular level

A

bacteria interact with cells lining the appendix

bacteria damages cells via toxins/cytolysins

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16
Q

what do the damaged cells release in appendicitis and what is the response to this

A

damaged cells release chemicals/cytokines which trigger inflammation

immune cells (neutrophil) leave blood vessels and travel to infection site - attracted to cytokine via chemotaxis

17
Q

E coli can communicate to other cells - explain what this means in terms of appendicitis

when do they communicate, what happens after communication

A

as resources decrease ecoli bacteria can communicate with other ecoli cells

some ecoli save resources and share DNA with other ecoli

ecoli can then develop into ninja ecoli which can bind to other cells and release toxin that can kill cells

18
Q

what happens in appendicitis when the immune system repsonds

A

neutrophils engulf the bacteria via phagocytosis

toxic granules fuse with the phagosome to form lysosome

bacteria are killed within lysosome

19
Q

how do lysosomes kill bacteria

A

by generating oxygen free radicals

20
Q

where is appendicitis pain felt initially and over time - why is this

A

nerves from appendix enter spinal cord at umbilicus level so initial pain is felt there

over time inflammation spreads to parietal peritoneum which has more precise innervation and pain shifts to right iliac fossa

21
Q

what are the potential outcomes of appendicitis

A

2 pathways it can proceed in:

  1. inflamed appendix is encased by omentum and forms chronic inflammatory appendiceal mass
  2. appendix bursts -> peritonitis -> sepsis -> death
22
Q

what are the 4 methods of management for appendicitis

A

pain relief

fluids

surgery

antibiotics

23
Q

when are antibiotics given for appendicitis if at all

A

antibiotics dont do much for appendicitis

can be given peri-operatively to reduce the risk of surgical wound infection but it only reduces risk by small amount

24
Q

what are the 3 things that streptococcus pyogenes cause

A

pharyngitis

skin infection/cellulitis

rheumatic fever or glomerulonephrosis following infection

25
Q

what are the symptoms of rheumatic fever - 5 things

A

fever

painful joints

connective tissue and heart muscle inflammation

rash

chorea (involuntary random muscle movements)

26
Q

describe how streptococcus pyogenes causes symptoms/diseases on the cellular level - 5 things

A

streptococcus pyogenes surface M proteins binds to pharynx cells

innate immune system activates and streptococcus pyogenes toxins damage pharynx cells

M protein resemble human tissue antibodies that form which can cross react

Can react to own tissues as antibodies formed against bacterial proteins sometimes bind to human tissues

antibody binding to human tissue (eg joints/heart etc) causes local inflammation unrelated to initial infection site

27
Q

bacteria cell wall is made up of what? what is the bacteria cell wall structure

A

repetitive carbohydrate blobs - NAM and NAG - which dont have good 3D structure

5 amino acids (peptide chain) hang off side of NAG - 5th aa is removed when 2 NAG peptide chains link

cross linking between peptide chains gives it structure

28
Q

what is the difference between gram + and gram - bacteria at the cellular level

A

gram + bacteria = thick cell walls made of many carbohydrate chains

gram - bacteria = one layer of carbohydrate making up cell wall

29
Q

what facilitates the cross linking of peptide chains in the bacterial cell wall

A

transpeptidase

30
Q

how does penicillin work in regard to the bacterial cell wall

A

penicillin binds to transpeptidase so that bacterial cell wall cannot maintain its integrity and falls apart