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3rd yr- IWB- Microbiology > Destruction of micro organism: sterilisation and disinfection > Flashcards

Destruction of micro organism: sterilisation and disinfection Flashcards

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Biology 101 flashcards
1
Q

Define decontamination

A

Decontamination is a combination of processes that removes or destroys contamination so that infectious agents or other contaminants cannot reach a susceptible site in sufficient quantities to initiate infection or other harmful response

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2
Q

Define sterilisation

A

Complete killing or removal of all types of micro organism (including spores)

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3
Q

Give examples of micro organism

A
  1. Eukaryotes
  2. Prokaryotes
  3. Viruses
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4
Q

Define anti sepsis

A

Disinfection applied to damage skin or living tissues

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5
Q

Define sanitisation

A

Removal of microbes that pose a threat to public health

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6
Q

Give examples of sterilisation methods

A
  1. Heat
  2. Chemicals
  3. Irradiation
  4. Filtration
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7
Q

How can we use heat to sterilise something

A
  1. Moist heat

2. Dry heat

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8
Q

What is the moist heat method of sterilisation

A
  1. Boiling,
  2. Autoclaving
  3. Exposure to super heated steam at controlled press and temperature cycle
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9
Q

Which is more effective autoclaving or boiling? Why?

A

Autoclaving as you can set the temperature and how long you want to sterilise something for eg 115 degrees at 30 mins or 134 degrees for 3 mins

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10
Q

How do autoclaves work

A

The air displacement method

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11
Q

Name the two sub types of the air displacement method

A
  1. Passive (type N) for unwrapped instruments

2. Vacuum (type B) for wrapped instruments

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12
Q

After sterilisation what is it important that we do?

A

Quality control to make sure the equipment has been sterilised properly

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13
Q

Name some different methods we can evaluate the efficacy of an autoclave machine

A
  1. The Bowie- Dick Test
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14
Q

Name some problems that can occur in an autoclave and what they can cause

A

Air leakage
Unwanted condensation
These can result in cold spots which will mean the equipment isn’t properly sterilised

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15
Q

Which of the 2:
dry heat exposure or autoclave saturated steam
Need a longer time to effectively sterilisation material

A

Dry heat needs longer
It runs t higher temperatures for a longer time Rame in comparison to autoclaves
Eg 160-170 degrees for 2 hours

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16
Q

When is it better to use dry heat over moist heat to sterilise something?

A
  1. When using metal as dry heat is not corrosive to metal

2. Some glass ware may get damaged in steam so better to use a dry heat method

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17
Q

Give examples of gas chemicals we can use for sterilisation

A

Ethylene oxide

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18
Q

Give examples of liquid chemicals we can use for sterilisation

A

Glutaraldehyde

formaldehyde

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19
Q

Name the irradiation we use to sterilise equipment

A
  1. Ultraviolet

2. Gamma radiation

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20
Q

Describe Ethylene oxide and how we use it for sterilisation

A

It is a highly flammable gas
We usually mix it with 90% CO2 to prevent it from igniting
useful in killing spores and bulky items that can’t fit into an autoclave

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21
Q

What is the main problem with Ethylene oxide?

A

It is highly flammable

Takes a long time to dissolve from surfaces so stays on the sterilised surface for some time after sterilisation

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22
Q

Give some disadvantage of using Glutaraldehyde

A

It can become inactivated in the presence of organic matter

It is very toxic so not commonly used

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23
Q

How is formaldehyde used?

A

Can be used in solution or as a vapour

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24
Q

When is formaldehyde used?

A

When a large area has been contaminated or when contaminated equipment like extractor fans are hard to reach

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25
Q

How does radiation get rid of microorganisms

A

It affects and breaks down their DNA leading to micro organism cell death

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26
Q

When is ultra violet used as a sterilisation method

A

To sterilise surfaces or air

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27
Q

What does ultraviolet not go through?

A

Glass due to its wavelength

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28
Q

What is gamma irradiation sometimes referred to as?

A

Cold sterilisation

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29
Q

What are gamma irradiations used to sterilise

A

Pharmaceuticals and medical and dental supplies

Equipment that can’t be sterilised by other methods

30
Q

What is filtration

A

Removal of micro organisms from liquids that are destroyed by heat
It does not destroy micro organisms but physically removes them

31
Q

What are membrane filters usually made out of

A

Nitro cellulose

32
Q

What is filtration usually used to sterilise

A

Liquids containing enzymes that could be denatured if they were heated (eg vaccines)

33
Q

If autoclaving is not useful what can we use?

A

Thermal washer disinfection

34
Q

What is thermal washer disinfection used to sterilise

A

Small dental equipments

35
Q

Is sub merging equipment into boiling water a good method for sterilisation?

A

NO it is not recommended by public health England

36
Q

Give examples of chemical disinfectants

A
  1. Alcohol based
  2. Chorine
  3. Iodine
37
Q

Give examples of alcohols that can be used as disinfectants

A
  1. Methanol
  2. Ethanol
  3. Isopropanol
    all
38
Q

Give examples of chlorine disinfectants

A

Sodium hypochlorite (bleach)

39
Q

Give examples of iodine disinfectants

A

Providone iodine

40
Q

Why is alcohol a good disinfectant?

A

As they dehydrate cells cause membrane disruption and cause co agulation of proteins

41
Q

Why is chlorine used as a disinfectant

A

As it prevents microbial growth in water supplies

42
Q

What is chlorine usually used to disinfect

A

Bodies of water like swimming pools

Used as bleach to clean up bodily fluids on surfaces

43
Q

When using chemical disinfectants what do we need to be cautious of?

A
  1. Clean the object first
  2. Make the chemical disinfectant fresh
  3. Use the correct concentrations of disinfectant
  4. Don’t mix disinfectant with other chemical
  5. Check the microbial spectrum
  6. Check what effect the chemical disinfectant has on spored
  7. May be corrosive and Double check fort hazards
44
Q

How are disposable items sterilised and what must they be labeled as?

A

Before use disposable items must be sterilised usually by gamma radiation
They should then be labelled clearly as single use unless otherwise approved by the infection control team

45
Q

How do we determine if something needs to be sterilised, disinfected, washed or disposed of?

A

We create a risk assessment based on the planned usage and likely spectrum of micro organisms you wish to eliminate

46
Q

Describe the application of an equipment that would have a low risk assessment

A

It is in contact with healthy skin or not in contact with patients

47
Q

What is the recommended decontamination method for a low risk equipment?

A

Cleaning

48
Q

Describe the application of an equipment that would have a medium risk assessment

A

Equipment is:

  1. In contact with mucous membrane or body fluids or
  2. Contaminated by virulent or readily transmitted organisms or
  3. For use on immunocompromised patients
49
Q

What is the recommended decontamination method for a medium risk equipment?

A

Sterilisation or high level disinfection

50
Q

Describe the application of an equipment that would have a high risk assessment

A

Equipment is inclose contact with a break in skin or mucous membrane
OR
Is needed for introduction into sterile body sites

51
Q

What is the recommended decontamination method for a high risk equipment?

A

Sterilisation

52
Q

How do we choose which method we should use to sterilise equipment?

A

Depends on the physical properties of the item itself and the properties of the packaging material

53
Q

What is chemical disinfection largely limited to?

A
  1. Environmental decontamination or surfaces or spills
    2, Antisepsis
  2. Heat sensitive items
54
Q

Which of the methods of sterilisation is the least hazardous?

A

Heat is the least hazardous so should be used wherever possible

55
Q

As future clinicians what diseases should we be aware of and give examples

A

We should be aware of transmissible spongiform encephalopathies like Creutzfeld-jakob disease

56
Q

What are transmissible spongiform encephalopathies?

A

Neurological disease

57
Q

What is Creutzfeld-jakob disease caused by?

A

Prions that are highly resistant to decontamination

58
Q

What is another name for Creutzfeld-jakob disease

A

Mad cow disease

59
Q

How does Creutzfeld-jakob disease spread?

A

Through tissues or infected meat or unsterilised surgical instruments

60
Q

What risk group do dental scalers fall under?

A

High risk as they are used on patients

61
Q

How do we decontaminate dental scalers:

Sterilise, disinfect, wash or single use?

A

Washing and sterilisation

62
Q

How do we sterilise dental scalers?

A

Moist heat using an autoclave

63
Q

What risk group do dental drill holders (not the hand-piece) fall under?

A

Low risk as they don’t touch the patient

64
Q

How do we decontaminate dental drill holders (not the hand-piece) :
Sterilise, disinfect, wash or single use?

A

Washing and disinfection

65
Q

How do we wash and disinfect dental drill holders (not the hand-piece)?

A

Chemically using an azowipe (70% isopropyl alcohol)

66
Q

What risk group do hand-pieces fall under?

A

High risk

67
Q

How do we decontaminate hand-pieces

Sterilise, disinfect, wash or single use?

A

Washing and sterilisation

68
Q

How do we sterilise hand-pieces?

A

Moist heat using an autoclave

69
Q

What risk group do dental burs fall under?

A

High risk

70
Q

How do we decontaminate dental burs

Sterilise, disinfect, wash or single use?

A

Single use

71
Q

What risk group do Endodontics reamers and files fall under?

A

High risk with special risk for Creutzfeld-jakob disease

72
Q

How do we decontaminate Endodontics reamers and files

Sterilise, disinfect, wash or single use?

A

Single use

3rd yr- IWB- Microbiology (12 decks)

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