9. Environmental Transmission

Question 1

Risk from equipment and the environment (4)

Answer 1

High risk (critical)
Medium risk (semi-critical)
Low risk (non-critical)
Minimal risk

Question 2

Definition of high risk equipment

Answer 2

Items in contact with normally sterile body sites

Question 3

Definition of medium risk equipment

Answer 3

Items in contact with intact mucous membranes

Question 4

Definition of low risk equipment (2)

Answer 4

Items in contact with intact skin

Cleaned/chemically disinfected

Question 5

Definition of minimal risk equipment (2)

Answer 5

Items not normally in contact with intact skin

Cleaned (chemically disinfected in risk assessed circumstances)

Question 6

Types of non-critical environmental surfaces (2)

Answer 6

Housekeeping surfaces

Clinical contact surfaces

Question 7

Features of housekeeping surfaces (2)

Answer 7

Not directly touched during dental treatment

Carry the lowest risk of disease transmission

Question 8

Features of clinical contact surfaces (2)

Answer 8

Contaminated from patient materials either by direct spray or spatter generated during dental procedures
Contaminated by contact with gloved hand of dental healthcare professional

Question 9

Influenza surface survival time (2)

Answer 9

Steel/plastic - 24-48hrs

Cloth, paper tissue - 8-12hrs

Question 10

Influenza transmission (3)

Answer 10

Steel to hands over 24hrs
Paper tissue to hands for 15mins
Viruses survives 5mins on hands

Question 11

Breaking the chain of infection from surfaces - reservoir

Answer 11

Surface design, surface material, cleaning, preventing recontamination, disinfectant/detergent

Question 12

Breaking the chain of infection from surfaces - portal of exit

Answer 12

Aerosol control

Question 13

Breaking the chain of infection from surfaces - mode of transmission

Answer 13

Hands, fomites

Question 14

Breaking the chain of infection from surfaces - portal of entry

Answer 14

PPE

Question 15

Breaking the chain of infection from surfaces - susceptible host

Answer 15

Vaccinations

Question 16

Common issues with surface cleaning (3)

Answer 16

Body fluid forms surface films (facilitates pathogen attachment)
Visual assessment of cleanliness (poor measure of invisible soiling)
Cleaning process - potential to re-contaminate surfaces

Question 17

Definition of detergent (2)

Answer 17

Group of synthetic organic water-soluble agents

Have wetting agent, emulsifying and soil holding properties

Question 18

Definition of disinfection

Answer 18

Process for the removal or destruction of microbes not usually including bacterial spores

Question 19

Features of high-level disinfectants

Answer 19

Kill all microbes (including mycobacteria) but not large numbers of bacterial spores
Usually require long contact time (hrs)

Question 20

Features of low-level disinfectants

Answer 20

Kill most vegetative bacteria, some fungi and some viruses

Practical period of time (<10mins)

Question 21

Portal of exit - aerosol control (2)

Answer 21

High volume aspiration

Rubber dam

Question 22

Portal of entry

Answer 22

PPE

Question 23

Definition of cleaning

Answer 23

Physical removal of contamination