POM 10 - Activities of a pathogen 2

Question 1

what are the 4 components of virulence factors

Answer 1

adherence

invasion

immune evasion

toxins

Question 2

what are virulence factors

Answer 2

the genetic determinants that allow a pathogen to cause disease

Question 3

explain the virulence factor of adherence

Answer 3

ability to interact or bind with humor cell

Question 4

explain the virulence factor of invasion

Answer 4

factors that enable bacteria to find a new niche

Question 5

explain the virulence factor of immune evasion

Answer 5

avoidance of innate immune system

most important factor

Question 6

explain the virulence factor of toxins

Answer 6

bacteria release to damage neighboring cells

Question 7

what is the most important virulence factor

Answer 7

immuen evasion

Question 8

what is virulence

Answer 8

the ability to cause disease in hosts with intact defences

Question 9

what does virulence require

Answer 9

some breech of host defences

Question 10

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

Answer 10

tissue invasion, multiplication, and immune response in sterile site

Question 11

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

Answer 11

evade innate immune system

activated macrophages fuse and surround the antigen

incomplete host response = granuloma

Question 12

what is bacterial intoxication

Answer 12

change in host physiology and tissue destruction

Question 13

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

Answer 13

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

Question 14

what happens at the start of appendicitis

Answer 14

appendix is obstructed with a faecolith

bacteria propogate

Question 15

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

Answer 15

bacteria interact with cells lining the appendix

bacteria damages cells via toxins/cytolysins

Question 16

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

Answer 16

damaged cells release chemicals/cytokines which trigger inflammation

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

Question 17

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

when do they communicate, what happens after communication

Answer 17

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

Question 18

what happens in appendicitis when the immune system repsonds

Answer 18

neutrophils engulf the bacteria via phagocytosis

toxic granules fuse with the phagosome to form lysosome

bacteria are killed within lysosome

Question 19

how do lysosomes kill bacteria

Answer 19

by generating oxygen free radicals

Question 20

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

Answer 20

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

Question 21

what are the potential outcomes of appendicitis

Answer 21

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

Question 22

what are the 4 methods of management for appendicitis

Answer 22

pain relief

fluids

surgery

antibiotics

Question 23

when are antibiotics given for appendicitis if at all

Answer 23

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

Question 24

what are the 3 things that streptococcus pyogenes cause

Answer 24

pharyngitis

skin infection/cellulitis

rheumatic fever or glomerulonephrosis following infection

Question 25

what are the symptoms of rheumatic fever - 5 things

Answer 25

fever

painful joints

connective tissue and heart muscle inflammation

rash

chorea (involuntary random muscle movements)

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

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

Answer 28

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

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

Question 29

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

Answer 29

transpeptidase

Question 30

how does penicillin work in regard to the bacterial cell wall

Answer 30

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