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Medicine Term One > Pathogens of the host > Flashcards

Flashcards in Pathogens of the host Deck (25):
1

What is a commensal

Organism part of normal flora

2

Pathogenicity

The capacity of a micro-organism to cause an infection

3

Pathogenicity requires

Infectivity -Ability to become established
Virulence - Ability to cause harmful effects once established

4

The ability to become established within a host dependant on

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

5

Pathogen

organism that causes a disease

6

What is virulence

ability to cause harmful effects once established

7

What are the three virulence factors

Invasivness
Toxin production
evasion of immune system

8

What is virulence specific to

strains not species

9

What is invasiveness

Multiplies and spreads around the body

10

what is toxin production

release toxins extracellular

11

Streptococcus pyogenes is an invasive bacteria causes what disorders

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

12

What is released extracellularly by the micrograms

exotoxins

13

what are enterotoxins

more specific exotoxins which act on the GI tract

14

what is endotoxin

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

15

What bacteria causes tetnus and what does it produce

clostridium tetani
an exotoxin

16

When and what does tetanus do
How is death caused?

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


17

How is tetanus treated

debridement (removal of damaged tissue), antibiotics and antitoxin

18

What bacteria is cholera and what does it produce

Vibrio cholerae, enterotoxin

19

What does cholera enterotoxin do

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

20

What are the two example of bacteria which produce superantigens

Strep pyogenes and Staph aureus

21

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

E. Coli - Gut
Staph. aureus - Nose

22

What do super antigens do

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

23

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

Lipid A

24

What are the seven things that characterise infection

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

25

What does it mean if someone is asymptomatic

Shows no symptoms