Principles of Infection III

Question 1

What are the 4 main stages of infection?

Answer 1

Transmission
Infection
Pathogenicity
Virulence

Question 2

What is the transmission stage of infection?

Answer 2

The host has to acquire the organism.

Question 3

What is the infection stage of infection?

Answer 3

The organism has to reproduce inside the host.

Question 4

What is the pathogenicity stage of infection?

Answer 4

Interacting the host in a way that causes disease.

Question 5

What is the virulence stage of infection?

Answer 5

This is the severity of the disease stage.

Question 6

What are the main virulence factors?

Answer 6

Adhere to and invade host tissues.
Evade host defences.
Proliferate in the host.
Cause damage = produce toxins // host - pathogens interactions.

Question 7

What does virulence factors allow to take place?

Answer 7

Enables the host to replicate and spread within a host.

Question 8

How is it possible to ‘evade host defences’?

Answer 8

Achieved by entering the bloodstream.

Question 9

What is the name given for the production of toxins?

Answer 9

Toxigenicity.

Question 10

What is the effect of the production of toxins?

Answer 10

This can cause tissue damage = which leads to LOW BLOOD PRESSURE.

Question 11

How does virulence factors arise?

Answer 11

These factors are often encoded and translated for genes in chromosomal DNA.

Question 12

What are pili adhesions ?

Answer 12

This is when the pili attaches a bacterial cell to a SPECIFIC surface // other cells.
This can aid in attachment between the bacterial cells.

Question 13

What process is pili adhesions attached to?

Answer 13

Adherence.

Question 14

What are the two types of invasions?

Answer 14

Intracellular.

Extracellular.

Question 15

What is intracellular invasion?

Answer 15

This when the microbe actually penetrates the cells of a HOST TISSUE and SURVIVES.

Question 16

What is extracellular invasion?

Answer 16

This is when a microbe breaks down the barriers of a tissue to spread in the host while remaining OUTSIDE of the host cells.

Question 17

Which enzymes aid extracellular invasion?

Answer 17

Staphylokinase
Hyaluronidase
Streptokinase

Question 18

What are the 3 main evade host defences for bacteria?

Answer 18

Capsule
Cell Wall
Toxins

Question 19

Explain more about the capsule host defence.

Answer 19

Protects the bacteria from phagocytosis.

DOES NOT allow opsonising antibodies to be recognised by phagocytic host defence cells.

Question 20

What are the host defence cells?

Answer 20

Macrophages

Neutrophils

Question 21

Explain more about the cell wall host defence.

Answer 21

These contain endotoxins and thus, activate a pathway of events which WEAKEN THE HOST.
The host deteriorates.

Question 22

What is the weakening of the host known as?

Answer 22

Septic Shock.

Question 23

Explain more about the toxins host defence.

Answer 23

These molecules are secreted by bacteria to destroy and damage host tissues.

Question 24

What are the 2 main evade host defences for viruses?

Answer 24

Antigenic Drift

Antigenic Shift

Question 25

Explain more about the Antigenic Drift.

Answer 25

BRINGS ABOUT MINOR CHANGE. | This is the accumulation of mutations within the genes which codes for antibody - binding sites.

Question 26

Explain more about the Antigenic Shift.

Answer 26

BRINGS ABOUT MAJOR CHANGE. 2 / more different strains of viruses combine. Forms a new subtype = This has a mixture of surface antigens of the 2 / more ORIGINAL strains.

Question 27

What is the horizontal gene transfer?

Answer 27

This enables bacteria to respond and adapt to their environment RAPIDLY by acquiring large DNA sequences from another bacterium in a single transfer.

Question 28

How are virulence factors determined?

Answer 28

These factors are genetically determined.

Question 29

What is the donor bacterium?

Answer 29

This carries the DNA sequence called the ' Fertility Factor.'

Question 30

What is a pilus?

Answer 30

This is a thin tube - like structure which is used as a cell adhesion mechanism.

Question 31

What is the 'F - Factor'?

Answer 31

Donor produces a PILUS. | They contact the recipient and thus, the donor bacterium transfers the genetic material to recipient bacterium.