ID 2

Question 1

WHat is a pathogen?

Answer 1

A microbe that causes disease

Question 2

What is a pathogen that does not cause disease/harm?

Answer 2

Commensal

Question 3

What is a saprophyte?

Answer 3

An organism that feeds on and decomposes dead organic matter

Question 4

What is bacteraemia?

Answer 4

A pathogen in the blood stream

Question 5

What is septicaemia?

Answer 5

Blood poisoning

Question 6

What is infection

Answer 6

Pathogens entering and colonising in host tissues

Question 7

What is an infectious disease?

Answer 7

A disease caused by a pathogen entering and colonising in host tissues

Question 8

Host pathogen relationships are dynamic. What does this mean?

Answer 8

They can modify each other’s activities

Question 9

What are pathogen determinants? Give examples

Answer 9

Any genetic/biochemical/structure that enables it to produce disease in a host
Virulence, entry route, host immune response, environment stability, infective dose

Question 10

What are host determinants? Give examples

Answer 10

A variable that can affect the frequency of disease within a population
Age, gender, species, immune strength (opportunistic), genes

Question 11

Pathogenesis is the mechanism that leads to disease. Describe this process

Answer 11

Host is exposed to pathogen
Pathogen adheres to skin or mucosa
Pathogen enters invades through the epithelium
Pathogen forms colony, produces virulence factors and grows
Further growth at new sites
Cause tissue damage and disease

Question 12

WHat are the 2 ways that virulence factors cause pathogenesis?

Answer 12

Promote damage

Promote colonisation

Question 13

What is a virulence factor

Answer 13

A molecule that increases the ability of a pathogen to cause infection

Question 14

What are exo and endotoxins?

Answer 14

Exotoxins produced by bacteria and released outside of cell

Endotoxins produced by bacteria and released inside cell

Question 15

What are the 3 types of exotoxins

Answer 15

Neurotoxins (brain)
Enterotoxins (GI)
Cytotoxins (all tissues)

Question 16

What are Koch’s postulates? No need to list them

Answer 16

4 criteria which establish a microbe as being the cause of a diseasee

Question 17

List Koch’s postulates

Answer 17

Microbe must be found in all sites and cases of disease
Microbe must be isolated from individual and placed in pure culture
Microbe must cause disease symptoms when inoculated into a new person
Microbe must be reisolated from intentionally infected host

Question 18

Virulence factors are identified by Falkow’s adaptation of Koch’s postulates. What are these:

Answer 18

Phenotype under investigation must be associated with pathogen
Inactivation of gene associated with pathogen should decrease virulence and pathogenicity
Reactivation of gene associated with pathogen should restore virulence and pathogenicity

Question 19

What are vaccinations?

Answer 19

Treatment given to produce immunity by stimulating the production of antibodies
Protect individuals, reduce transmission and infection

Question 20

What are the advantages disadvantages of live vaccinations?

Answer 20

Returning to virulence
Not allowed during pregnancy
Long lasting
Oral/nasal/parental
Cheap

Question 21

What are the advantages and disadvantages of killed/attenuated vaccines?

Answer 21

Expensive
Injected/parenteral routs
Ok for pregnancy
Need multiple doses
Short lasting

Question 22

What is a recombinant vaccine?

Answer 22

Treatment to stimulate immune response, made by inserting DNA that codes for an antigen into another’s DNA molecule

Question 23

What is a subunit vaccine?

Answer 23

Vaccine constructed from antigenic components of a pathogen e.g. proteins

Question 24

What is an antitoxin vaccine?

Answer 24

Vaccine against a toxin a pathogen produces, rather than the pathogen itself

Question 25

WHat is sterile immunity?

Answer 25

Complete prevention of an infection

Question 26

What is the immunological method used by vaccines?

Answer 26

Antigens recognised and phagocytosed
presenting of antigens on surface to T cells
T cells produce clones - T cells, helper, killer
T cells activate B cells which divide to plasma cells

Question 27

What is the difference between cell mediated response and humoral response? In immunity

Answer 27

Cells themselves destroy pathogen e.g. cytotoxic T cells, phagocytes
Humoral - produce antibodies to destroy the pathogen