Pathogens of the host

Question 1

What is a commensal

Answer 1

Organism part of normal flora

Question 2

Pathogenicity

Answer 2

The capacity of a micro-organism to cause an infection

Question 3

Pathogenicity requires

Answer 3

Infectivity -Ability to become established

Virulence - Ability to cause harmful effects once established

Question 4

The ability to become established within a host dependant on

Answer 4

Pathogens attachment

pathogens acid resistance (e.g. high acidic level in the stomach)

Question 5

Pathogen

Answer 5

organism that causes a disease

Question 6

What is virulence

Answer 6

ability to cause harmful effects once established

Question 7

What are the three virulence factors

Answer 7

Invasivness
Toxin production
evasion of immune system

Question 8

What is virulence specific to

Answer 8

strains not species

Question 9

What is invasiveness

Answer 9

Multiplies and spreads around the body

Question 10

what is toxin production

Answer 10

release toxins extracellular

Question 11

Streptococcus pyogenes is an invasive bacteria causes what disorders

Answer 11

Necrotising fasciitis
Cellulitis
Connective tissue breakdown
Fibrinolysis - the enzymatic breakdown of the fibrin in blood clots

Question 12

What is released extracellularly by the micrograms

Answer 12

exotoxins

Question 13

what are enterotoxins

Answer 13

more specific exotoxins which act on the GI tract

Question 14

what is endotoxin

Answer 14

structurally part of the Gram negative cell wall that is release when disintegrates

Question 15

What bacteria causes tetnus and what does it produce

Answer 15

clostridium tetani

an exotoxin

Question 16

When and what does tetanus do

How is death caused?

Answer 16

Happens through contaminated wounds
toxin production binds to nerve synapse and inhibits release of inhibitory neurotransmitters.
death = respiratory paralysis

Question 17

How is tetanus treated

Answer 17

debridement (removal of damaged tissue), antibiotics and antitoxin

Question 18

What bacteria is cholera and what does it produce

Answer 18

Vibrio cholerae, enterotoxin

Question 19

What does cholera enterotoxin do

Answer 19

Increases cAMP levels which inhibits uptake of Na and Cl ions causes outflow of water into GI tract resulting in dehydration due to watery diarrhoea

Question 20

What are the two example of bacteria which produce superantigens

Answer 20

Strep pyogenes and Staph aureus

Question 21

What are two examples of the commensal flora in the gut and nose

Answer 21

E. Coli - Gut

Staph. aureus - Nose

Question 22

What do super antigens do

Answer 22

able to stimulate t cells proliferation therefore increasing cytosine resulting in toxic shock

Question 23

What part of the gram negative bacterial cell wall is the endotoxin

Answer 23

Lipid A

Question 24

What are the seven things that characterise infection

Answer 24

Inflammation 
Pain
Pyrexia (fever)
Tachycardia 
Rigors (sustained shaking)
Increased white cell count 
Increased C reactive protein (markers of infection)

Question 25

What does it mean if someone is asymptomatic

Answer 25

Shows no symptoms