Sterilisation Flashcards Preview

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

Flashcards in Sterilisation Deck (61):
1

Define Sterility according to the OED

(When something is) Free from living microorganisms

2

Define Sterility according to Winfield and Richards

The total absence of viable microorganisms and an absolute state

3

Define Sterility according to Hugo and Russell

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

4

Define Achievable Sterility

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

5

What is the Sterility Assurance Level (SAL)

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

6

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

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

7

Define D value in terms of radiation

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

8

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

FALSE. Z value only applies to heat sterilisation

9

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

Thermal resistance

10

What is Bioburden

The concentration of microorganisms in a material

11

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

TRUE

12

What is meant by Inactivation factor (IF) ?

The number of D values needed to achieve sterility assurance level

13

State the IF equation

10 to the power t/D

t = contact time or dose

D = D value

14

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

TRUE

15

State one advantage of heat sterilisation

Destroys all enzymes and other essential cell components

16

State one 'disadvantage' of heat sterilisation

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

17

State the 2 types of heat used in heat sterilisation

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

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

18

Name the 3 stages involved in heat sterilisation

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

19

What is the most commonly used method of terminal sterilisation

Moist heat sterilisation

20

State 6 products sterilised using moist heat sterilisation

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

21

What equipment is commonly used for moist heat sterilisation ?

Autoclave

22

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

121 - 134 degrees celcius

121 - 15 minutes
or
134 - 3 minutes

23

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

TRUE

24

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

Denaturation and Coagulation


(therefore stop cells from replicating etc)

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