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Stage 2, Cycle 2 - Sterility and Asepsis > Sterilisation > Flashcards

Sterilisation Flashcards

(61 cards)

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1
Q

Define Sterility according to the OED

A

(When something is) Free from living microorganisms

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2
Q

Define Sterility according to Winfield and Richards

A

The total absence of viable microorganisms and an absolute state

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3
Q

Define Sterility according to Hugo and Russell

A

A product that doesn’t contain viable bacteria, yeasts or fungi nor other microorganisms such as protozoa, viruses etc

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4
Q

Define Achievable Sterility

A

The probability of microorganisms surviving should be low enough to ensure patient safety

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5
Q

What is the Sterility Assurance Level (SAL)

A

10 to the power -6. (One in a million chance)

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6
Q

Define D value (Decimal reduction time) in terms of heat sterilisation

A

Time taken at a fixed temperature to reduce the number of viable organisms by 90%

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7
Q

Define D value in terms of radiation

A

The radiation dose required to reduce the number of viable organisms by 90%

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8
Q

Z value applies to both heat sterilisation ad radiation. TRUE or FALSE

A

FALSE. Z value only applies to heat sterilisation

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9
Q

Z value assesses the influence of heat changes on ….?

A

Thermal resistance

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10
Q

What is Bioburden

A

The concentration of microorganisms in a material

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11
Q

To assure sterility, the bioburden must be as small as possible at the start of the process. TRUE or FALSE

A

TRUE

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12
Q

What is meant by Inactivation factor (IF) ?

A

The number of D values needed to achieve sterility assurance level

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13
Q

State the IF equation

A

10 to the power t/D

t = contact time or dose

D = D value

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14
Q

Heat sterilisation is the most reliable and most widely used method. TRUE or FALSE

A

TRUE

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15
Q

State one advantage of heat sterilisation

A

Destroys all enzymes and other essential cell components

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16
Q

State one ‘disadvantage’ of heat sterilisation

A

Can only be used with products that can handle the heat i.e: thermostable products

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17
Q

State the 2 types of heat used in heat sterilisation

A

1) Dry heat (for moisture sensitive products i.e: dressings)

2) Moist heat such as STEAM (for moisture resistant products)

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18
Q

Name the 3 stages involved in heat sterilisation

A

1) Heating stage
2) Holding stage
3) Cooling stage

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19
Q

What is the most commonly used method of terminal sterilisation

A

Moist heat sterilisation

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20
Q

State 6 products sterilised using moist heat sterilisation

A

1) Some dressings
2) Clothing
3) Equipment
4) Aqueous injections
5) Irrigation fluids
6) Opthalmic preparations

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21
Q

What equipment is commonly used for moist heat sterilisation ?

A

Autoclave

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22
Q

What is temperature range of an autoclave and how long for ?

A

121 - 134 degrees celcius

121 - 15 minutes
or
134 - 3 minutes

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23
Q

Shorter time in the autoclave causes less product damage and higher IF value. TRUE or FALSE

A

TRUE

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24
Q

Moist heat sterilisation causes ….. and …. of essential proteins?

A

Denaturation and Coagulation

therefore stop cells from replicating etc

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25
Describe the F value
The mathematical method of converting time in the heating and cooling stage to time spent at 121 degree Celsius.
26
What is the F value useful for ?
Products where holding time at 15 mins isn't possible
27
Dry heat sterilisation isn't as commonly used as moist heat. Why ?
Higher temperature and longer exposure time; is needed for this process
28
Dry heat sterilisation is mostly used in hospitals o surgical equipment. TRUE or FALSE
TRUE
29
DHS is useful for sterilisation of glassware. How ?
DHS ensures depyrogenation as pyrogens stick to glassware
30
Name a product sterilised using dry heat
Thermostable powders
31
Non-aqueous thermostable liquids such as Alcohol is used in DHS. TRUE or FALSE
TRUE
32
What equipment and temp range is used for DHS ?
Hot air oven. 160 - 180 degrees for up to 2 hrs
33
What temperature and how long for is required for depyrogenation of glassware ?
250 degree Celsius, 45 minutes
34
DHS has lethal effects due to oxidative processes. TRUE or FALSE
TRUE
35
Name 2 types of gas used in Gaseous sterilisation
1) Ethylene oxide | 2) Formaldehyde (not commonly used due to smell and risk)
36
Gaseous sterilisation is generally used for temp sensitive items. TRUE or FALSE. Give examples of these items
TRUE; - Medical, diagnostic and electrical equipment used in operating theatres (microscopes, tubing etc) -
37
Formaldehyde and Ethylene oxide can be mutagenic and carcenogenic. TRUE or FALSE
TRUE
38
Ethylene oxide can be detected by smell whilst Formaldehyde cannot. TRUE or FALSE
FALSE, it's the other way round
39
Gaseous sterilisation gases cause alkylation on what groups on proteins ?
- Carboxyl, Hydroxyl, Amino and Sylphydryl | basically denaturation of protein
40
Gaseous sterilisation gases cause alkylation on what groups on nucleic acids ?
Imino group
41
What does Ethylene oxide have to be mixed with in order to be used?
Carbon dioxide (10%) OR HFC 124 (8.6%)
42
Ethylene oxide mixed with more than 3.6% v/v of air will explode. TRUE or FALSE
TRUE
43
Gases are good at penetrating materials. TRUE or FALSE
TRUE. e.g: raw powders
44
800-1200mg/L at 45-6oC is the essential range for gases used for gaseous sterilisation. TRUE or FALSE
TRUE. Gas is left under this temp for around 4hrs
45
Gas is let back out into the environment at the end of the sterilisation process. TRUE or FALSE
TRUE
46
After gaseous sterilisation (using both ethylene oxide and Formaldehyde), products must be left for at least 24hrs to desorb toxins/toxic gas. TRUE or FALSE
TRUE
47
Formaldehyde is a liquid. What is it mixed with to turn it into a gas ?
Water and heat with steam to 70-75oC; for around 4hrs
48
Formalin contains what %w/v of formaldehyde
37% w/v
49
State 3 methods of Radiation sterilisation and highlight the most effective
1) Accelerated electrons (Particulate radiation) 2) Gamma-ray (Electromagnetic radiation) - Most effective/least dangerous 3) UV light (Electromagnetic radiation) - least effective
50
Gamma ray is usually performed on Industrial scale manufacture. TRUE or FALSE
TRUE
51
State one 'disadvantage' of Gamma ray radiation sterilisation
Can damage aqueous solutions and certain types of packaging
52
Gamma ray radiation sterilisation can be used on dry products such as ?
1) Surgical equipments 2) Plastic syringes 3) Dry powders 4) Dressings
53
The D value of GRRS is connected to ...... of radiation not the time ?
Dose
54
What source is used for GRRS ?
Cobalt 60
55
What is the half life of cobalt 60 ? What is the standard dose of cobalt 60, i kGy ?
5.25 years 25kGy
56
Define Disinfection
The process of removing microorganisms from the surface of inanimate objects
57
State 6 types of Chemical agents used for disinfection
1) Alcohol (Most safe/least toxic) - Aldehydes - Halogens - Peroxygens - Phenolics - Quaternary ammonium compounds
58
State 2 types of biological indicators
1) Standardised bacterial spore preparations 2) Suspensions or Spores dried onto paper, plastic or Aluminium - Placed in with each load for sterilisation - Cultured after cycle has ended
59
State the BI organism used in Moist heat sterilisation. State its D value and Log IF also
B. Stearothermophilus D value - 1.5 mins Log IF - 10
60
State the BI organism used in Dry heat sterilisation. State its D value and Log IF also
B. subtilis var. niger D value - 10 mins max Log IF - Min. 12
61
State the BI organism used in Irradiation sterilisation. State its D value and Log IF also
B. pumilus D value - 3kGy Log IF - 8.3

Stage 2, Cycle 2 - Sterility and Asepsis (4 decks)

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