Sterilisation

Question 1

What is the definition of Sterilise?

Answer 1

To destroy all living organisms

Question 2

What is the definition of Disinfect?

Answer 2

To make free from infection by destoying all organisms in the vegetative state (spores not included)

Question 3

What is the definition of Antisepsis?

Answer 3

Destruction or inhibition of organisms on living tissues

- limiting or preventing the harmful results of infection

Question 4

What is the definition of Sanitise?

Answer 4

To reduce the total bioburden

- Reference to utensils and equipment

Question 5

What is the definition of Steriliser?

Answer 5

A piece of equipment by which sterilisation may be achieved

Question 6

What is the definition of Autoclave?

Answer 6

A piece of equipment by which sterilisation may be achieved using steam under pressure
- Simple, inexpensive, safe and reliable

Question 7

What is the definition of Sterile supply?

Answer 7

The location where sterile items and equipment are dispensed
- In a small clinic this is usually a bench area with laundry

• In a large clinic it is usually a dedicated room

Should be arranged to separate dirty from the clean

Question 8

What are the required conditions for steam sterilisation?

Answer 8

1. Sufficient moisture to allow full penetration
2. Complete contact
3. Correct temperature to kill organisms
4. Correct contact time

Question 9

What are the different types of autoclave?

Answer 9

1. Single shelled autoclaves - no drying cycle

2. Double shell autoclaves - preferable

Question 10

What are the main components of the sterilisation process?

Answer 10

1. Cleaning
2. Packing
3. Appropriate items
4. Loading/ unloading
5. Times and pressures
6. Sterilisation indicators
7. Storage

Question 11

How do you clean instruments for sterilisation?

Answer 11

Sterilisation often ineffective if any organic material present

• Rinse in cold water
• Wash in tepid water with enzymatic cleaner
• Rinse and dry
• Ultrasonic cleaners

Question 12

How do you pack instruments for sterilisation?

Answer 12

Cloth wraps, kimguard or paper backed plastic pouches

• Trays: wrapped
• Single instruments: packed
• Multiple instruments not in tray: double bagged
• Larger items : wrapped then pouched

Question 13

What is of most importance of packing material for sterilisation?

Answer 13

What and how you wrap has an effect on whether or not the objects achieve sterility

Question 14

How do you know what items are appropriate for autoclaving?

Answer 14

• Generally autoclaves can’t process delicate instruments
• Follow item instructions or note maximum temperature
• • Many plastics will melt at 134C but survive 121C

Question 15

How do you Load/ Unload instruments for sterilisation?

Answer 15

• Allow free circulation and penetration of steam
• Enhance air elimination
• Prevent entrapment of air and water
• Leave untouched with autoclave door open for 30 mins before unloading

Question 16

What is important to remember about warm autoclave packages?

Answer 16

If they are placed on a cold surface they will become damp from condensation and become unsterile

Question 17

What are the times and pressures for autoclave sterilisation?

Answer 17

15psi @ 121C for 15 minutes

30psi @134C for 3-4 minutes

Question 18

What different things can be used as sterility indicators?

Answer 18

• Indicator tape
• Indicator strips
• Browne tubes
• Biologic indicators
• Batch controllers

only indicate that cerain conditions have been met

Question 19

What do browne tubes do?

Answer 19

Test air removal

- Determines time, steam and temperature

Question 20

What is important about biological indicators?

Answer 20

They are the only way of determining that thermophilic bacteria cannot have survived

Question 21

What are recommended storage times for items?

Answer 21

• Double wrapped Kimguard: 6 months
• Single paper pouches : 6 months
• Double paper pouches: 6 months
• Drapes/linen/Kim guard : 1 month
• Paper pouches : 6 months

Question 22

What are the best conditions for equipment storage?

Answer 22

• Correct temperature and humidity
• Low traffic area
• Minimal handling

Question 23

What are the advantages of autoclaves?

Answer 23

• Steam is readily available
• Cheap
• Quick
• Reliable
• Sterilises most things
• Equipment can be stored afterwards

Question 24

What are the disadvantages of autoclaves?

Answer 24

• Requires special equipment
• Requires careful monitoring
• Cannot sterilise delicate or sharp instruments

Question 25

What are some other methods of sterilisation?

Answer 25

- Dry heat - Chemical gas sterilisation - Chemical cold sterilisation - Ionising gamma radiation - Plasma sterilisation

Question 26

What is dry heat sterilisation?

Answer 26

- Oxidative denaturation of proteins - Bacterial spores show greater resistance - Longer exposure times are thus needed

Question 27

What are the advantages of dry heat sterilisation?

Answer 27

- Simplicity - Sealed containers can be used - Doesn't dull instruments - Fairly cheap - No moisture - Non-corrosive - Sterilised oils and powders

Question 28

What are the disadvantages of dry heat sterilisation?

Answer 28

- Long exposure times - Careful loading technique required to ensure all parts of the load are sterilised - Requires careful monitoring - Unsuitable for heat sensitive materials; paper, cloth, plastics etc

Question 29

Describe chemical gas sterilisation...

Answer 29

- Ethylene oxide ETO - Flammable, explosive gas which becomes an effective steriliser when mixed with CO2 - Kills by alkylation of DNA - Was used for equipment that couldn't be autoclaved - Items have longer shelf life - Slow - Expensive - Toxic to people

Question 30

Describe chemical cold sterilisation...

Answer 30

- Must be non-corrosive - Used for delicate items - Immersion time is critical - Normally 15 mins - No longer than 60 mins

Question 31

Describe ionising radiation sterilisation...

Answer 31

- Gamma radiation (cobalt 60) - Most manufactured equipment which is pre-packaged is sterilised this way e.g. sutures - Less readily available to vets

Question 32

Describe plasma sterilisation...

Answer 32

- Low temperature technique - Not available in vets - Vapour phase hydrogen peroxide sterilises by active ions, electrons and neutral atomic particles to kill bacteria