Sterility and Aseptic Techniques Flashcards
What does ‘HEPA’ stand for?
High Efficiency Particulate Air
What is the smallest size of particle that a standard HEPA filter will block?
0.5 micrometers
What is meant by the term ‘turbulent Flow’?
Swirling airflow
What the problems associated with ‘turbulent Flow’?
Turbulent flow air picks up particles which can be deposited on surfaces and containers
What is meant by the term ‘laminar flow’?
Parallel streams of unidirectional air
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?
Background air is loaded with particles and micro-organisms which provide an extra challenge to the LFA cabinet
What does a ‘pre-filter’ do?
Pre-filter removes larger particles and helps protect the HEPA filter
Also extends the life of a HEPA filter
How would you prepare a cabinet before you prepared an injection?
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.
In which part of the cabinet would you expect to optimise the conditions for asepsis?
It is necessary to work up stream of any sources of contamination such as equipment and the consumables used when preparing injections etc.
What is likely to disturb the laminar flow conditions?
Sudden movements, equipment, and heat sources such as Bunsen burners
How would you minimise turbulence?
By making slow and deliberate movements and having the minimum of equipment etc. to upset the laminar flow air
What is the purpose of testing the inside of the cabinet for particulates?
To show that HEPA filter is achieving the standard for freedom of particles
What is the purpose of testing the inside of the cabinet for airborne microorganisms?
To show the environment is sterile
What is the purpose of testing the inside of the cabinet for filter integrity?
To show that the HEPA filter doesn’t have any leaks or there isn’t a faulty seal
What is the purpose of testing the inside of the cabinet for air velocity?
To show that the air velocity complies with a standard and can prevent egress of dirty air
How often can microorganisms double?
Every 20 mins
What tests would you use to ensure an aseptic unit was working to the standards of the orange guide?
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
Explain the differences between terminal sterilisation and aseptic manufacture:
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.
Describe disinfection:
The process of removing microorganisms, including potentially pathogenic ones, from the surfaces of inanimate objects
Describe antisepsis:
Destruction or inhibition of microorganisms on living tissues having the effect of limiting or preventing the harmful effects of infection
Describe antiseptic:
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
What are the three types of disinfectants and describe:
High level- destruction of all, some spores
Intermediate level- Excluding some virus and fungi and spores
Low level- Most vegetative bacteria
Name the different class HEPA filters and describe:
1- airborne drawn in
2- protects user- keeps air out
3- aseptic, air locks
Describe alcohols as a disinfectant:
Ethanol and isopropanol
Not 100% needs water around 65-95
Poor penetration to organic material
Doesn’t kill spores
Describe phenols as a disinfectant:
Not sporicidal
Very toxic
Poor penetration to organic matter
Describe aldehydes as a disinfectant:
Formaldehyde
Not affected by organic matter
Sporicidal activity
Toxic and irritant so used in closed system, e.g not in pharmacy
Describe biguanides as a disinfectant:
Chlorhexadine
Non toxic to skin
Not effective against sporicidal or mycobacteria
Name and describe the graded clean areas:
C+ D= clean area for less critical stages
B= background environment for grade A zone
A= sterile, high risk operations
Give advantages and disadvantages of moist heat sterilisation:
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
Give advantages and disatvantages of dry heat sterilisation:
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
Give advantages and disadvantages of chemical sterilisation:
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
Give advantages and disadvantages of radiation sterilisation:
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
Give advantages and disadvantages of filtration sterilisation:
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
Name 7 antimicrobial preservatives:
Parabens
Phenolics
Alcohols
Quaternary Ammonium Compounds
Chlorhexidine
Chloroform
Benzoic/Sorbic Acid
Which don’t ointments need an antimicrobial preservative?
No aqueous phase
Describe the test used to measure the AMP efficacy and explain its procedure:
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
