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Flashcards in Pathogens of the host Deck (25)
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1
Q
What is a commensal
A
Organism part of normal flora
2
Q
Pathogenicity
A
The capacity of a micro-organism to cause an infection
3
Q
Pathogenicity requires
A
Infectivity -Ability to become established
Virulence - Ability to cause harmful effects once established
4
Q
The ability to become established within a host dependant on
A
Pathogens attachment
pathogens acid resistance (e.g. high acidic level in the stomach)

5
Q
Pathogen
A
organism that causes a disease
6
Q
What is virulence
A
ability to cause harmful effects once established
7
Q
What are the three virulence factors
A
Invasivness
Toxin production
evasion of immune system
8
Q
What is virulence specific to
A
strains not species
9
Q
What is invasiveness
A
Multiplies and spreads around the body
10
Q
what is toxin production
A
release toxins extracellular
11
Q
Streptococcus pyogenes is an invasive bacteria causes what disorders
A
Necrotising fasciitis
Cellulitis
Connective tissue breakdown
Fibrinolysis - the enzymatic breakdown of the fibrin in blood clots
12
Q
What is released extracellularly by the micrograms
A
exotoxins
13
Q
what are enterotoxins
A
more specific exotoxins which act on the GI tract
14
Q
what is endotoxin
A
structurally part of the Gram negative cell wall that is release when disintegrates
15
Q
What bacteria causes tetnus and what does it produce
A
clostridium tetani
an exotoxin
16
Q
When and what does tetanus do
How is death caused?
A
Happens through contaminated wounds
toxin production binds to nerve synapse and inhibits release of inhibitory neurotransmitters.
death = respiratory paralysis


17
Q
How is tetanus treated
A
debridement (removal of damaged tissue), antibiotics and antitoxin
18
Q
What bacteria is cholera and what does it produce
A
Vibrio cholerae, enterotoxin
19
Q
What does cholera enterotoxin do
A
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
Q
What are the two example of bacteria which produce superantigens
A
Strep pyogenes and Staph aureus
21
Q
What are two examples of the commensal flora in the gut and nose
A
E. Coli - Gut
Staph. aureus - Nose
22
Q
What do super antigens do
A
able to stimulate t cells proliferation therefore increasing cytosine resulting in toxic shock
23
Q
What part of the gram negative bacterial cell wall is the endotoxin
A
Lipid A
24
Q
What are the seven things that characterise infection
A
Inflammation
Pain
Pyrexia (fever)
Tachycardia
Rigors (sustained shaking)
Increased white cell count
Increased C reactive protein (markers of infection)
25
Q
What does it mean if someone is asymptomatic
A
Shows no symptoms

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