Entry and Spread

Question 1

Name 3 parts of the body that is sterile

Answer 1

1. Blood
2. Pleural fluid
3. Joint fluid

Question 2

Name 3 parts of the body that is non-sterile

Answer 2

1. Respiratory tract
2. Skin
3. Gastrointestinal tract

Question 3

Name 3 things that transmission depends on

Answer 3

1. number of organisms shed
2. how stable the organism is in the environment
3. the infectious dose

Question 4

Name 6 types of transmission and give an example for each

Answer 4

1. respiratory and salivary spread, e.g. coughing
2. faecal-oral spread, e.g.
3. venereal spread, e.g. sex
4. vector, e.g. malaria
5. vertebrate reservoir (harbour microorganisms), e.g. rabies
6. vector-vertebrate, e.g. plague

Question 5

What are the 4 main routes of transmission?

Answer 5

1. Inhalation
2. Absorption
3. Ingestion
4. Injection

Question 6

Describe the transmission from respiratory tract and pharynx

Answer 6

Droplets expelled when sneezing and coughing, droplets can be inhaled
pharyngeal - exchange of saliva

Question 7

Describe the transmission from gastrointestinal tract and the F-Diagram

Answer 7

faeces has potential aerosol, particles in air, pathogens ingested
faeces –> fluids, flies, fingers, fields –> food and new host

Question 8

Describe the transmission from urinary and genital tract

Answer 8

Urinary tract infection - usually endogenous causes (E. coli)
Genital tract infection - physical contact between individuals, absorption, perinatal during birth

Question 9

Other modes of transmission

Answer 9

skin, milk, blood

Question 10

What is the level of risk to humans of a hazard group 1 agent?

Disease? Spread? Treatment?

Answer 10

Unlikely to cause human disease

Question 11

What is the level of risk to humans of a hazard group 2 agent?

Disease? Spread? Treatment?

Answer 11

Can cause disease, unlikely to spread to community, usually effective treatment available

Question 12

What is the level of risk to humans of a hazard group 3 agent?

Disease? Spread? Treatment?

Answer 12

Can cause severe human disease, may spread to community, usually effective treatment available

Question 13

What is the level of risk to humans of a hazard group 4 agent?

Disease? Spread? Treatment?

Answer 13

Causes severe human disease, likely to spread to community, usually no effective treatment

Question 14

What are the practices and equipment used in a containment level 1 lab?

Answer 14

Good microbiology technique (GMT),

just open bench

Question 15

What are the practices and equipment used in a containment level 2 lab?

Answer 15

GMT, protective clothing (PPE), bio-hazard sign,

bio-safety cabinet for aerosols

Question 16

What are the practices and equipment used in a containment level 3 lab?

Answer 16

Level 2 + special clothes, controlled access, directional airflow,

BSC, primary devices for all activities

Question 17

What are the practices and equipment used in a containment level 4 lab?

Answer 17

Level 3 + airlock entry, shower

Class 3 BSC, positive pressure suits

Question 18

Name 5 control measure in labs

Answer 18

Personal protective clothing (PPE)
- gloves, lab coat, goggles, hair tied back
Sharps bin
Virkon (disinfectant)

Question 19

Give the four main virulence categories of virulence factors.

Answer 19

1. adhesins
2. evasins and impedins
3. invasins
4. toxins