Pathogens and Hosts

Question 1

In what 7 ways can clinical infections be characterised?

Answer 1

Inflammation
Pain
Pyrexia
Tachycardia
Rigors
Increased white cell count
Increased C Reactive Protein

Question 2

What are the 2 types of clinical infection?

Answer 2

Latent

Sub-clinical

Question 3

Define a pathogen.

Answer 3

Organism which can cause disease.

Question 4

Define commenal.

Answer 4

Organism which is part of the normal flora.

Question 5

What are Koch’s postulates?

Answer 5

Four criteria that were established by Robert Koch to identify the causative agent of a particular disease.

Question 6

What are the 4 Koch’s postulates?

Answer 6

Organism must be found in all cases of the disease
Be cultured outside the body
Reproudce the disease on inoculation

Question 7

Define pathogenicity.

Answer 7

Capacity of a micro-organism to cause an infection.

Question 8

Define infectivity.

Answer 8

Ability to become established.

Question 9

Define virulence.

Answer 9

Ability to cause harmful effects once established.

Question 10

Name the pathogen which would attach for infectivity.

Answer 10

E.Coli

Question 11

Name the pathogen which would be acid resistant for infectivity.

Answer 11

Helicobacter pylori

Question 12

What is virulence conferred by?

Answer 12

Virulence factors.

Question 13

How do streptococcus pyogenes invade?

Answer 13

Necrotising fasciitis
Cellulitis
Connective tissue breakdown
Fibrinolysis

Question 14

Define exotoxins.

Answer 14

Released extracellularly by the microorganism.

Question 15

Define enterotoxins.

Answer 15

Exotoxins which act on the GI tract.

Question 16

Define endotoxin.

Answer 16

Structurally part of the gram negative cell wall.

Question 17

Name an exotoxin disease.

Answer 17

Clostridium Tetani

Question 18

How does clostridium tetani cause death?

Answer 18

Respiratory paralysis.

Question 19

How is clostridium tetani treated?

Answer 19

Debridement
Antibiotics
Antitoxin

Question 20

Name an enterotoxin disease.

Answer 20

Cholera

Question 21

How does cholera cause death?

Answer 21

Dehydration.

Question 22

How is cholera treated?

Answer 22

Rehydration.

Question 23

What are superantigens?

Answer 23

Certain exotoxins of strep pyogenes and staph aureus.

Question 24

What do superantigens do?

Answer 24

Stimulate division of T cells in the absence of specific antigen, causing toxic shock from overwhelming cytokine production.

Question 25

What part of the lipopolysaccharide is an endotoxin?

Answer 25

Lipid A

Question 26

Name two types of endotoxin.

Answer 26

E.Coli

Neisseria meningitidis

Question 27

What host responses are induced by endotoxins?

Answer 27

Cytokine production
Fever
Rigors
Hypotension
Tachycardia
Collapse