M: Sterilization 2 - Week 8

Question 1

Name and describe 2 new techniques used for chemical based sterilisation?

What makes these techniques better than previous ones?

Answer 1

Sterrad process: uses hydrogen peroxide as the sterilizing agent that breaks down to h2o and O2

Sterris process: uses peracetic acid as the sterilizing agent. However you need to rinse the article with sterile water after it’s been sterilised with paracetic water

— these techniques are far less toxic and are still effective

Question 2

Explain process monitoring

Answer 2

Check that the sterilisation process has been effective by measuring and assessing many parameters

Question 3

Name 3 parameters assessed in process monitoring

Answer 3

1. Physical indicators (temp, time, pressure)
2. Chemical indicators (sterilisation strip that changes colour, autoclave tape)
3. Biological indicators (spore strips)

Question 4

What is the best way to make the sterilisation process more effective?

Answer 4

Prevent problems in the first place by checking the critical points in the process. Then you are less likely to have unsterilised loads coming out of the autoclave

Question 5

What does HACCP stand for?

Answer 5

Hazard Analysis Critical Control Points

Question 6

When is disinfection often used and what does this achieve?

Answer 6

Before sterilisation. It reduces the initial load of organisms originally in the article and therefore reduces the time it takes to reach the sterility assurance level desired

Question 7

Name 3 methods of disinfection

Answer 7

• simple washing and cleaning
• hot water or steam for shorter times
• chemical disinfectants

Question 8

Name 3 purposes of hand washing.

Answer 8

• remove transient bacteria and debris
• reduce resident flora
• inhibit rapid rebound of bacteria growth

Question 9

True or false: hand washing can completely remove resident flora

Answer 9

False. It can only reduce it

Question 10

Describe the features of an ideal hand wash:

Answer 10

• affects broad spectrum of microbes
• non irritant and non allergenic
• has rapid and residual action

Question 11

Which disinfectants work best?

Answer 11

Aldehydes and halogens because they have a broad spectrum and biocidal action

Question 12

How good of a disinfectant is chlorine? Explain

Answer 12

Poor. Chloride does not work at cold temperatures and it needs low organic activity

Question 13

Which disinfectant can cause contact dermatitis?

Answer 13

Iodophors, which is a halogen disinfectant

Question 14

For the following chemical disinfectants, state the dilation used to disinfect tonometers and gonioscopy prisms:
A) Chlorine
B) Hydrogen Peroxide
C) Alcohols

Answer 14

A: Chlorine - 0.4-0.5% solution
B: Hydrogen Peroxide - 3% solution
C: Alcohols - 70% solution

Question 15

What disinfectants should be made fresh when you use them? Why?

Answer 15

Halogens and Hydrogen peroxide. Because they are not stable and solutions will only last a short time (around a day or so)

Question 16

What affects the disinfectant action of chlorine? List 3 influencing factors

Answer 16

• temperature
• pH
• organic material

Question 17

Out of the following disinfectants, which are active against spores, cysts and enveloped viruses?
- Halogens
- Alcohols
- Phenols
- Chlorhexidine (biguanide)

Answer 17

Halogens

The rest are all not active against spores. Alcohols are not active against cysts too while phenols and chlorhexadine are both not active against non-enveloped viruses

Question 18

What factors affect the efficiency of a disinfectant? List 5 factors

Answer 18

1. concentration
2. contact time
3. temperature
4. pH
5. presence of organic material

Question 19

What affects your choice of disinfectant? List 4 factors

Answer 19

1. type and state of microorganisms
2. contact time available
3. physical nature of surface or article
4. allowable concentration

Question 20

How essential is pre-cleaning prior to disinfection?

Answer 20

Very

Question 21

When are strong oxidising agents like hydrogen peroxide, chlorine dioxide and peracetic acid considered “sporicidal”?

Answer 21

When they are at a high concentration

Question 22

What are halogens active against? (4)

Answer 22

Active against:
- most bacteria and viruses, including HIV and HIB
- spores and cysts

Question 23

When would you use iodophor as an alternative to chlorhexidine?

Answer 23

When broader spectrum of bactericidal and soricidal action needed

Question 24

How would you describe the spectrum of action for strong oxidizing agents like hydrogen peroxide, chlorine dioxide and peracetic acid?

Answer 24

Reasonably broad spectrum of action

Question 25

What can affect the activity of chlorhexadine?

Answer 25

anions and soap

Question 26

What are QACs? What does QAC stand for?

Answer 26

Quaternary Ammonium Compounds (e.g. cetrimide)
- are cationic surface-active disinfectants

Question 27

What are QACs useful for?

Answer 27

Useful for gram positive bacteria and non-enveloped viruses, otherwise limited or no activity

Question 28

Is 0.9% saline a disinfectant?

Answer 28

NO!

Question 29

When cleaning contact lenses, what does rubbing them accomplish?

Answer 29

Rubbing removes biofilms. Biofilms are much more resistant to disinfectants compared to individual bacteria