Chapter 11 Sterilization

Question 1

Define sterilization

Answer 1

Process of destroying all microorganisms on or in an object

Question 2

What does the Safety Assurance Level ‘mean?

Answer 2

Probability of a single viable microorganism occurring on a product after sterilization

Question 3

What is the difference between high, intermediate and low level disinfectants?

Answer 3

High: Kill any microorganism present (large quantity of spores = only exception)

Intermediate: Don’t kill bacterial spores

Low: Kill most vegetative bacteria and some fungi/spores

Question 4

What is cavitation?

Answer 4

Ultrasonic waves are used to create minute gas bubbles, which then implode, creating minute vacuum –> particle removal

Question 5

List 5 properties of ideal wrapping material

Answer 5

1. Prevent microbial penetration
2. Permeable to sterilizing agent
3. Resistant to physical damage and moisture penetration
4. Minimal memory
5. Long shelf life
6. (if using steam, resistant to heat)
7. (if using ethylene oxide, allow for aeration)

Question 6

what does cold sterilization refer to?

List 3 examples of cold sterilization agents

Answer 6

Soaking instruments in disinfectant

1. Glutaraldehyde
2. Hydrogen peroxide
3. Peracetic acid

Question 7

List typical cycle in displacement autoclave

Answer 7

121°C for 30 mins

OR

132°C for 15 mins

Question 8

What is the n=preferred term for flash sterilization?

Answer 8

Immediate use steam sterilization (IUSS)

NOt recommended excpt in emergency, not for implants.

Question 9

Aside from steam (and cold sterilization) list 5 methods of sterilization

Answer 9

1. Ethylene oxide
2. Ozone (4 hour cycle)
3. Plasma (Sterrad): electromagnetic energy to create plasma phase from am vapour of hydrogen peroxide, oxygen or peracetic acid –> reactive free radicals that deactivate cellular process. Relatively short cycle time, no toxic residues, able to sterilize wide range of equipment.
4. Vaporized hydrogen peroxide
5. Radiation (cobalt 60 gamma rays)

Question 10

what are the three types of monitors for sterilization?

Answer 10

Physical (print out) chemical (eg reactive strips) or biological (micro-organisms )

Question 11

How many classes of chemical indicators are there? give an example of class 1

Answer 11

6 classes

Class 1: Placed on outside, indicates has been exposed to a sterlization process. E.g. sterilization tape

Class 6: Placed internally and reacts to all critical parameters of sterilization cycle

Question 12

Which microorganism is used as a bilogical indicator for steam, plasma and ozone sterilizers?

And for ethylene oxide?

Answer 12

• Geobacillus stearothermophilus*
• Bacillus atrophaeus*

Question 13

For storage of sterilized items, what are the temperature, humidity and air exchange recommendations?

Answer 13

<24ºC

<70% humidity

At least 4 air exchanges/hour

Question 14

How long can an autoclaved pack be kept for?

And ethylene oxide?

Answer 14

96 weeks

1 year for heat sealed plastic (less if paper etc wrapping)