Bacteria And Viruses

Question 1

What does a pathogen do in the progression from asymptomatic to symptomatic infection?

Answer 1

It spreads, multiplies and causes damage.

Question 2

If a pathogen enters a persons normal microbiota what can be said about that person?

Answer 2

They are a carrier of that pathogen.

Question 3

What is often the reservoir in an infection?

Answer 3

Another animal species.

Question 4

How can we reduce hospital infections?

Answer 4

Remove stages 1 or 2
1 - reservoir
2 - immediate source.
This includes HCWs washing hands thoroughly and isolation of infectious patients.

Question 5

What is R0 and what does it tell us?

Answer 5

R0 is the rate at which infection causes colonisation in uninfected individuals. If R0>1 then infection propagates. If R0

Question 6

What name do we give to a microorganism which is incapable of producing disease and lives in the body naturally?

Answer 6

Non-pathogen

Question 7

Define pathogen.

Answer 7

A microorganism such as virus, bacteria, yeast or fungi which parasitises an animal or human producing disease.

Question 8

What is antibiotic resistance?

Answer 8

This is where a person may not complete a course of antibiotics and so all the weak bacteria have been killed and the stronger ones remain, maybe one with a resistant gene. These multiply and then a new strain of the bacteria form which all have the resistant gene. This gene can be passed by conjugation and horizontal gender transmission to the bacteria strains.

Question 9

What is the difference between an infection and an infectious disease?

Answer 9

Infection is the invasion and multiplication of bacteria/viruses in the body. Infectious disease is where this causes a disorder.

Question 10

What is the normal microbiota?

Answer 10

Aggregation of microorganisms found on the surface/ deep skin.

Question 11

What is a commensal infection?

Answer 11

This is when one organism benefits from another, without the other being affected.

Question 12

What does gram staining tell us about the properties of bacteria?

Answer 12

It tells us how thick the peptidoglycan cell wall is. The thick wall does not allow extraction of the crystal violet and so this is gram positive.

Question 13

Name two internal features which bacteria can posses.

Answer 13

Spores

Granule

Question 14

What is a fimbriae which can be found on bacteria?

Answer 14

It is a tail on the cell/pilli where exchange of DNA can take place.

Question 15

Give two reasons why bacterial cell walls are clinically important

Answer 15

They allow detection and diagnosis via acid fast and gram stains.
They are the target for antibiotics.

Question 16

What is a bacterial biofilm?

Answer 16

This is where bacterial agent infect intravascular devices such as cannulas.

Question 17

What is required for bacterial growth?

Answer 17

An energy source, building blocks and an appropriate atmosphere.

Question 18

What is a virus?

Answer 18

A virus is a microorganism but is much smaller than bacteria. It has to use the mechanisms of the host cell in order to survive.

Question 19

What molecule do enveloped viruses contain?

Answer 19

Lipids. These are more susceptible to disinfectants compared to non-enveloped viruses.

Question 20

Comment on the difference in growth rate between bacteria and viruses.

Answer 20

Bacteria show exponential growth, whilst viruses show incredibly rapid growth. When a cell bursts, many viruses are released.

Question 21

What is the difference between +RNA and -RNA in viruses?

Answer 21

+RNA can act as mRNA and can therefore produce proteins.

Question 22

A Virion is an entire virus particle. What two components is it made up from?

Answer 22

Inner nucleic acid core.
Outer protein shell which is called the capsid. This protects the inner nucleic acid core and can be involved in attachment to host cells.

Question 23

What is syncytia formation which can occur in viral infections?

Answer 23

This is where multi nucleated cells form by fusion of plasma membranes.

Question 24

Explain how retroviruses can cause cancer.

Answer 24

Retroviruses turn on the cells oncogenes causing it to replicate uncontrollably.

Question 25

Explain how DNA viruses can cause cancer.

Answer 25

These viruses deactivate tumour suppressor proteins meanings cells continuously go through the cell cycle and start proliferating.

Question 26

Why do we get symptoms when we have an infection?

Answer 26

We get symptoms because the body overreacts to microorganisms.

Question 27

What is a latent infection?

Answer 27

This is where there is microorganism presence but it is not sufficient to cause symptoms.

Question 28

Why do recurrent infections occur?

Answer 28

There are always microorganisms present in the body, and their numbers reduce sufficiently that there are no symptoms but then they multiply and it becomes a symptomatic infection once again.

Question 29

Give an example of a gram negative cocci bacterium.

Answer 29

Neisseria

Question 30

How can staphylococcus and streptococcus both be classified? (How do they respond to gram staining?)

Answer 30

Gram positive cocci

Question 31

Classify the bacterium: Clostridium

Answer 31

Bacilli, gram negative.

Question 32

Give examples of gram positive bacilli bacteria

Answer 32

Salmonella, pseudomonas, legionella, helicobater, escherichia.

Question 33

Classify papilloma viruses.

Answer 33

They are non enveloped DNA viruses.

Question 34

Give three examples of an enveloped DNA virus

Answer 34

Hepatitis B, herpes, small pox

Question 35

Give examples of an enveloped RNA virus

Answer 35

Rubella, HIV, rotavirus, corona virus.

Question 36

What is an endogenous infection?

Answer 36

Where infection occurs by a pathogen which is found in a persons normal microbiota.