Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

The Medicine - Y3 > Sterilisation > Flashcards

Sterilisation Flashcards

(69 cards)

Start Studying
1
Q

What are the two approaches to achieving a sterile product?

A

1) Produce under ‘clean’ conditions and terminally sterilise in final container
2) Aseptic technique - produce under conditions free of microorganisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the potential sources of microbial contamination within a manufacturing environment?

A

Raw material - synthetic and natural
Water - essential for microbial growth so if used to wash/cool products will increase growth
Manufacturing environment - air/equipment/personnel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the sources of resident microorganisms?

A

Water
Soil
Plants
Animals and humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the sources of transient microorganisms?

A

Water and air is a vector for these microorganisms and they are harder to control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the definition of sterile?

A

Free of viable microorganisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the definition of sterilisation?

A

The killing or removal of viable microorganisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the sterilisation techniques that kill microorganisms?

A

Heat - dry/moist
Chemical - ethylene oxide
Radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the sterilisation process that removes microorganisms?

A

Filtration sterilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How would an antibiotic contained in a vial with a stopper be sterilised?

A

Antibiotic sterilised using filtration technique
Vial - Steam sterilisation as can’t pass through filter
Stopper - EtO
Antibiotic then filled in vial aspetically and sealed aseptically before it is packaged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are sterilisation standards used for?

A

Control number of microorganisms
Validate the sterilising agent
Validate the sterilisation process
Monitor the sterilisation process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is meant by an asymptote curve?

A

Each time it decreases by the same proportion but never reaches zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What order of kinetics is demonstrated by inactivation kinetics kill curve?

A

First order

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is a kill curve produced?

A

Culture of cells taken and exposed to sterilant for increasing number of time
At different time points, remove a sample and perform a viable count
Plot the number of survivors against time to produce an asymptote curve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How can a kill curve be plotted to allow the calculation of a thermal death rate i.e. y and x axis?

A

Plot log of number of survivors against time to give a semi-logarithmic graph
Will give you a straight line so you can calculate the gradient and this is the thermal death rate (thermal if temp used)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

An asymptote curve can be used to compare results when organism exposed to different temps and when different organisms exposed to the same temp. True or false?

A

False - use a semi-logarithmic graph for this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the four key points about inactivation kinetics?

A

Infinite probability of survival
First order kinetics
Organism specific
Affected by concentration of sterilant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define D value

A

The time taken (at fixed temp/conc/radiation) to reduce the population of microorganisms by 90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

A 90% reduction in population of microorganisms is how many log cycles?

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the units of D expressed as?

A

minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Z value is only for which type of sterilisation?

A

Heat sterilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Define Z value and interpret its meaning

A

The temp change required to reduce D-value by 90% i.e. temp change required to reduce the time taken to reduce pop by 90% by 90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the units of Z-value?

A

Degrees C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How can thermal resistance be measured?

A

Z value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What can be used to make sense of data produced by Z-value?

A

Biological indicator used as a standard

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Which BI is used in moist heat sterilisation?
Bacillus stearothermophilus - Z =10
26
Which BI is used for dry heat sterilisation?
Bacillus subtilus - Z = 20
27
What is used as an indicator of sterility?
SAL = 10-6
28
What is the length of your sterilisation process determined by?
Resistance of microorganism Type of microorganism Number of microorganisms present
29
What are the 5 things that influence D-value?
``` Bacterial species Vegetative vs spore Treatment dose Production method Nutrient environment ```
30
What is the definition of bioburden estimation and what is its importance?
The population of viable microorganisms in or on a product/package Important in specifying sterilisation parameters and inactivation kinetics
31
What are the steps in bioburden estimation?
``` Sample selection Collect items for test Transfer to test lab Treat (if required) Transfer to culture medium Incubation Eumeration and characterisation Interpretation of data ```
32
During the bioburden estimation process, the sample may need to be treated by removal of cells. What determines the technique used for removal?
``` Ability to remove microbial contaminants The effect of removal on viability Types and location of microorganisms Nature of product Culture conditions ```
33
What are the different stages of process validation?
Installation qualification - checking steriliser works Performance - checking it sterilises Physical - checking levels of radiation/heat etc Microbiological - confirms physical and for EtO as physical not poss
34
What is a biological indicator and what is its use?
An innoculated carrier in a primary pack that provides definite resistance to a specified sterilisation process It is used as a direct assessment of microbial lethality of a sterilisation process
35
Which BI is used for filtration sterilisation?
Brevundimonas deminuta
36
Which BI is used for radiation sterilisation?
Bacillus pumilus
37
Which BI is used for EtO?
Bacillus subtilus
38
What are BIs characterised by?
``` D value Z value CFU per test piece Expiry date Recommended storage conditions ```
39
What 4 factors govern choice of BI?
Non-pathogenic Recoverability Resistance Stability
40
What is the specific guidance given for the selection of a sterilisation technique?
Agent needs to be in contact with all parts of the product No toxicity Not harmful/hazardous to operators of environment Process variables are controlled and monitored
41
Explain filtration sterilisation
Fluid passes across a filter removing any contaminating particles. Particles that don't pass: - irregular shape - simultaneous arrival of two particles - large particle blocking the pore - interaction between the particle and matrix of filter
42
What are the two types of filters for sterilisation and outline key differences between them
Depth and screen Depth filters have a non-uniform pore size, they have high voidage. They are cheap and robust and they don't achieve sterility. Particles sediment by inertial impaction Screen filters have uniform particle sizes, the pores are easily blocked. They are fragile and expensive but achieve sterility when the pore size is less than 0.22um. Particles sediment by direct interception
43
What are the two methods of filter validation?
Bubble point pressure test - filter with water on top and apply pressure from bottom until bubbles form Challenge filter with BI - brevundimonas diminuta and aim to achieve removal of 10^7 cells/cm^2
44
How are microorganisms killed by moist heat sterilisation?
Hydrolysis and protein coagulation
45
How are microorganisms killed by dry heat sterilisation?
Oxidative processes
46
What technology is used for dry heat sterilisation and what are the mechanisms of heat transfer?
Technology: dry heat ovens and sterilising tunnels | Heat transfer: convection (most common), radiation, conduction
47
What are the critical aspects of dry heat sterilisation?
Air circulation, loading pattern and particle size
48
What are the 4 stages of a dry heat cycle?
Drying Heating Exposure Cooling
49
Why is moist heat sterilisation faster than dry heat sterilisation and which one is used more commonly?
Moist heat is faster as microorganisms are killed faster by oxidative processes than hydrolysis. Moist heat is more common
50
What technology is used in moist heat sterilisation and what is the mechanism of heat transfer?
Autoclave | Latent heat of vaporisation
51
What are the critical aspects of moist heat sterilisation?
Saturated steam Air removal Steam under pressure
52
What are the critical lethal parameters of moist heat sterilisation?
Dry saturated steam not wet Temperature +/- 5K of limit Time of contact - sufficient to give SAL 10^-6 Bioburden level
53
What are the 5 stages of autoclave operation for moist heat sterilisation?
``` Air removal Heat Sterilise Cool Dry ```
54
What are the 3 autoclave cycle types for moist heat sterilisation?
Porous load - fabrics Fluid cycle - glassware Air ballasted cycle - plastic
55
What are the validation methods used for moist heat sterilisation
Master temperature record - thermocouples - min 12 | Temperature record chart - drain probe temp
56
What is moist heat sterilisation used for?
Aqueous products medical devices dressings
57
What is dry heat sterilisation used for?
Dry powders Oil preparations Glasswear
58
What is radiation sterilisation used for?
Single use medical devices | Containers
59
How does radiation sterilisation kill microorganisms?
Radiation induces chemical change in the vital components of the microbial cell by ejection of orbital electrons from the atom or molecule -> death
60
What is the minimum sterilisation dose for radiation sterilisation?
25kGy
61
What is the ionising source for radiation sterilisation?
Cobalt 60
62
What is EtO sterilisation used for?
Disposable items
63
How does EtO sterilisation work?
Alkylation of sulfhydryl, amino and carboxyl groups on proteins and nucleic acids
64
All sterilisation methods provide the same levels of sterility. True or false?
False - EtO doesn't provide same levels
65
Which sterilisation method can leave toxic residues post sterilisation?
EtO
66
What are the critical lethal parameters for EtO?
``` Time - 1-24hrs Temp - 25-65 degrees Relative humidity - 40-85% EtO concentration - 250-1200mg/L BI: bacillus subtilus ```
67
What equipment is used in EtO sterilisation?
Pre-conditioning Sterilising Aeration
68
Name some new and emerging technologies for sterilisation and identify some of the problems they raise
X-ray Microwaves Pulsed light They have unknown lethal effects and no established regulatory requirements
69
What are the 7 steps in the EtO sterilisation cycle?
``` Evacuation Vacuum hold Conditioning Sterilant injection Exposure Sterilant removal Flushing ```

The Medicine - Y3 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions