Sterility and Aseptic Techniques

Question 1

What does ‘HEPA’ stand for?

Answer 1

High Efficiency Particulate Air

Question 2

What is the smallest size of particle that a standard HEPA filter will block?

Answer 2

0.5 micrometers

Question 3

What is meant by the term ‘turbulent Flow’?

Answer 3

Swirling airflow

Question 4

What the problems associated with ‘turbulent Flow’?

Answer 4

Turbulent flow air picks up particles which can be deposited on surfaces and containers

Question 5

What is meant by the term ‘laminar flow’?

Answer 5

Parallel streams of unidirectional air

Question 6

Why is it necessary to have located a LFA cabinet in a room which is itself a dedicated clean room if used for preparing injections?

Answer 6

Background air is loaded with particles and micro-organisms which provide an extra challenge to the LFA cabinet

Question 7

What does a ‘pre-filter’ do?

Answer 7

Pre-filter removes larger particles and helps protect the HEPA filter
Also extends the life of a HEPA filter

Question 8

How would you prepare a cabinet before you prepared an injection?

Answer 8

Wipe clean all internal surfaces of the cabinet with a non-residue antimicrobial solution such as industrial methylated spirits (IMS) 70% and wait adequate time for solution to work.

Question 9

In which part of the cabinet would you expect to optimise the conditions for asepsis?

Answer 9

It is necessary to work up stream of any sources of contamination such as equipment and the consumables used when preparing injections etc.

Question 10

What is likely to disturb the laminar flow conditions?

Answer 10

Sudden movements, equipment, and heat sources such as Bunsen burners

Question 11

How would you minimise turbulence?

Answer 11

By making slow and deliberate movements and having the minimum of equipment etc. to upset the laminar flow air

Question 12

What is the purpose of testing the inside of the cabinet for particulates?

Answer 12

To show that HEPA filter is achieving the standard for freedom of particles

Question 13

What is the purpose of testing the inside of the cabinet for airborne microorganisms?

Answer 13

To show the environment is sterile

Question 14

What is the purpose of testing the inside of the cabinet for filter integrity?

Answer 14

To show that the HEPA filter doesn’t have any leaks or there isn’t a faulty seal

Question 15

What is the purpose of testing the inside of the cabinet for air velocity?

Answer 15

To show that the air velocity complies with a standard and can prevent egress of dirty air

Question 16

How often can microorganisms double?

Answer 16

Every 20 mins

Question 17

What tests would you use to ensure an aseptic unit was working to the standards of the orange guide?

Answer 17

a) Environmental tests
Settle plates for micro-organisms
Active air sampling for airborne micro-organisms
b) Equipment test
Filter integrity testing
Air velocity inside a LFA cabinet
c) Operator tests
Finger dabs for micro-organisms

Question 18

Explain the differences between terminal sterilisation and aseptic manufacture:

Answer 18

Terminal sterilisation: the product is made completely, packed into its final container, and then sterilized.
Aseptic manufacture: the various ingredients of the product may be individually sterilized (usually by passing solutions through bacteriaproof filters) and then mixed together using sterile equipment under conditions that do not allow the entry of microorganisms.

Question 19

Describe disinfection:

Answer 19

The process of removing microorganisms, including potentially pathogenic ones, from the surfaces of inanimate objects

Question 20

Describe antisepsis:

Answer 20

Destruction or inhibition of microorganisms on living tissues having the effect of limiting or preventing the harmful effects of infection

Question 21

Describe antiseptic:

Answer 21

A word used to describe a procedure that is intended to avoid the unwanted transfer of microorganisms from one object or location to another
The process of removing microorganisms, including potentially pathogenic ones, from the surfaces of inanimate objects

Question 22

What are the three types of disinfectants and describe:

Answer 22

High level- destruction of all, some spores
Intermediate level- Excluding some virus and fungi and spores
Low level- Most vegetative bacteria

Question 23

Name the different class HEPA filters and describe:

Answer 23

1- airborne drawn in
2- protects user- keeps air out
3- aseptic, air locks

Question 24

Describe alcohols as a disinfectant:

Answer 24

Ethanol and isopropanol
Not 100% needs water around 65-95
Poor penetration to organic material
Doesn’t kill spores

Question 25

Describe phenols as a disinfectant:

Answer 25

Not sporicidal
Very toxic
Poor penetration to organic matter

Question 26

Describe aldehydes as a disinfectant:

Answer 26

Formaldehyde
Not affected by organic matter
Sporicidal activity
Toxic and irritant so used in closed system, e.g not in pharmacy

Question 27

Describe biguanides as a disinfectant:

Answer 27

Chlorhexadine
Non toxic to skin
Not effective against sporicidal or mycobacteria

Question 28

Name and describe the graded clean areas:

Answer 28

C+ D= clean area for less critical stages
B= background environment for grade A zone
A= sterile, high risk operations

Question 29

Give advantages and disadvantages of moist heat sterilisation:

Answer 29

Advantages:
*Terminal sterilisation process for aqueous solutions or suspensions
* Wide safety margin
* Kills bacteria and viruses
Disadvantages:
* Only useful for thermostable products
* Can not be used for products with oily bases
* Water is essential

Question 30

Give advantages and disatvantages of dry heat sterilisation:

Answer 30

Advantages:
* Used for substances affected by moisture
* Suitable for assembled apparatus e.g., glass syringes
* Less damaging to glass and metal equipment than moist heat
Disadvantages:
* Drastic conditions are not tolerated by certain packaging material e.g., plastics/rubber
* Not suitable for surgical dressings
* Does not penetrate as well as moist heat
* Natural moisture in fibres vaporises and causes deterioration

Question 31

Give advantages and disadvantages of chemical sterilisation:

Answer 31

Advantages:
* Few materials damaged
* Minimal heat, minimal moisture
* Good penetration in porous loads
* Will penetrate rubber & plastics
* Effective against all micro-organisms * Bacteria, viruses, moulds
* Effective at relatively low humidity and temperature
Disadvantages:
* Costs higher than dry/moist heat
* Gas is toxic and flammable

Question 32

Give advantages and disadvantages of radiation sterilisation:

Answer 32

Advantages:
* Effective against a large number of bacteria, yeasts, moulds and some viruses
* Terminal technique
* Used for surgical instruments,
* Dry pharmaceutical products (powders)
* Highly efficient
* Can be used for thermo-labile products
Disadvantages:
* Not effective against some viruses * Cost
* Large installation, training, disposal * Dangerous
* Perceived side effects

Question 33

Give advantages and disadvantages of filtration sterilisation:

Answer 33

Advantages:
* Used for thermolabile products
* Removes bacterial dead bodies
Disadvantages:
* Can not be used for suspensions
* Not a terminal process
* Sterility tests required so 7-14 day delay
* Viruses and mycoplasms not removed

Question 34

Name 7 antimicrobial preservatives:

Answer 34

Parabens
Phenolics
Alcohols
Quaternary Ammonium Compounds
Chlorhexidine
Chloroform
Benzoic/Sorbic Acid

Question 35

Which don’t ointments need an antimicrobial preservative?

Answer 35

No aqueous phase

Question 36

Describe the test used to measure the AMP efficacy and explain its procedure:

Answer 36

The test consists of challenging the preparation, preferably in its final container, with a prescribed innoculum of suitable microorganisms , storing it at a prescribed temperature, and withdrawing samples at specified times