Aseptic techniques Flashcards
What is sterility assurance level
The probablity of micro-organisms surviving after exposure to sterilisation
What is terminal sterilisation
Sterilisation of the fully assembled product as a last step
What is aseptic processing
Sterilisation of the raw materials separately and the subsequent assembly of the mateirals following aseptic techniques.
What are the two approaches to the production of sterile products
- Aseptic processing
- Terminal sterilisation
List the physical sterilisation methods
- Filtration
- Radiation
- Heat sterilisation (steam/dry heat)
What is an autoclave
A machine used for steam sterilisation
What are the application of steam sterilisation
- Porous loads (e.g. Theatre gowns & dressing packs)
- Flexible and semi-rigid containers (e.g. Infusion solutions, bags, bottles)
What is a common issue with sterilisation of flexible&semi-rigid containers and how does the autoclave resolve this
- Bursting of the container
- Due to build up of pressure in the air space inside the bags/bottles.
‘Air ballasting’ which maintaints a proportion of air within the chamber to prevent package breakage
What are the limitations of steam sterilisation
- Cannot be used on oily-base products
- Only applicable to thermostable and moisture-stable products
What are the applications of dry heat sterilisation
- Thermostable dry powder
- Oily injections
- Glassware
- Metal instruments
- Depyrogenation of glass (250c for 45mins)
What are the advantages/ disadvantages of dry heat sterilisation
Advantages:
* Good alternative for moisture sensetive materials
* Suitable for assembled apparatus (terminal sterilisation)
* Can be used for depyrogenation
Disadvantages:
* Not suitable for plastics and rubber
* Not suitable for surgical dressings - Natural moisture in fibres vaporises causing detoriation
Steam sterilisation mode of action
- Protein denaturation
- Hydrolysis of bacterial enzymes
Radiation sterilisation advantages
Advantages:
* It is a terminal technique
* Highly efficient
* Can be used for thermo-labile (sensetive) products
Radiation sterilisation application
- Surgical instruments
- Sutures
- Prostheses
- Dry powders
Disadvantages of radiation sterilisation
- Not effetive against some viruses
- High cost: Large installation, training, disposal
- Dangerous
Filtration sterilisation application
Only used for liquids
Filtration sterilisation advantages
- Good for thermo-labile products
- Removes bacterial dead bodies
Filtration sterilisation disadvantages
- Cannot be used for suspensions
- Product requires equires sterility test post-sterilisation
- Filter requires frequent monitoring and checking
- Filtration does not remove viruses, mycoplasms
What are the two types of gas sterilisations
- Alkylating agents (Ethylene oxide)
- Oxidising agents (Hydrogen peroxide)
What are the advantages of gas sterilisation
Advantages:
* Good penetration in porous materials
* Effective against all micro-organisms
* Effective at relatively low humidity and temperature (less likely to damage material)
What are the disadvantages of gas sterilisation
Disadvantages:
* Can take up to 10 days
* More expesive than dry/steam
* Gas is toxic and flammable (dangerous)
* Some plastics and nylon wraps need to be left opened and then sealed aseptically after sterilisation
Radiation sterilisation mode of action
Microbial DNA damage via the formation of highly reactice radicals
What is dry heat sterilisation mode of action
Mainly an oxidative process
What is the best sterilisation technique for the depyrogenation of glass
Dry heat
Good sterilisation technique for dressing packs
Steam sterilisation
Good sterilisation technique for surgical tools
Radiation
High level disinfectant
Destruction of all microorganisms but not necessarily bacterial spores
Intermediate level disinfectant
Destruction of ALL vegatative bacteria but excluding some viruses and fungi
Low level disinfectant
Can destroy MOST vegatative bacteria, some fungi and viruses
What are alcohol disinfectants & their application
- Bactericidal against vegatative bacteria and mycobacteria (Ethanol, isopropanol)
- Require some water for effectiveness (Alcohol conc. 60-95%)
- High concs. are virucidal & fungicidal (e.g. 90%)
- Used to disinfect surfaces and skin
- They are not sporicidal
What are phenol disinfectants & their application
- Bactericidal - Vegetative bacteria
- Not sporicidal
- More active at acidic pH
- Caustic effect on skin (BAD)
- Diluted phenols are used as preservatives and antiseptics
Concentrations for phenols
Concentrations
✓0.1%-1% → Bacteriostatic.
✓1%-2% → Bactericidal and fungicidal
Aldehydes disinfecants adn give examples
- Highly effective biocides that disrupt the cell membrane
- They are partial sporicides
- Formalin, Glutaraldehyde
What is Formaldehyde and what is it used for
An aldehyde disinfectant with maxinum activity above 20c that is used for safety cabiners and isolators.
* It is irritant to skin
* Its vapours are carcinogenic
What is Glutaraldehyde and its application
An aldehyde disinfectant that is broad spectrum against bacteria, fungi, viruses and spores. Used for instruments and closed systems but not for open surfaces.
What are pyroxygen disinfectants
Highly active disinfectants that can act as sporicidal at high concentration and temperature. Otherwise the act as surface disinfectants.
* Hydrogen peroxide - Open woulnds
* Peracetic acid - Used in enclosed systems.
What is the aim of Aseptic processing
To maintain the sterility of a product throughout each step of its component assembly
What are aseptic techniques
A set of precautions and conditions that need to be followed during manufacturing process
Explain the differences between terminal sterilisation and aseptic techniques
Terminal sterilisation involves the product being sterilised in their final form and container AFTER they have been manufactured and packaged whereas aseptic manufacture involves…
* Maintaining a sterile environement for the storage of products and manufacturing processes.
* Personel training and use of PPE regulations
* Routine cleaning and monitoring of the environment and finished product via microbiological monitoring
What are microbiological monitoring techniques
Processes involved in quality assurance. These assess levels of contamination and cleanliness in a sterile environment.
* Finger dabs
* Air sampling
* Surface sampling
What does the finger dab technique achieve
Assesses the level of sterile manipulation and following of aseptic techniques of the individual. It is conducted in each session to assess individuals competence towards tho.
What does air sampling achieve
An important way of monitoring microbiological contamination of the environment in which the aseptic techniques and manufacture process is carried out in
What are two methods of sampling air contamination in a lab
- Settle plates - Leave an agar plate exposed and opened for a few hours then incubate
- Active air sampling - The use of a microbial air sampler which aspirates air into the machine and impacts it onto the agar plat.. incubate
Explain surface sampling
An important aspect of quality insurance by measuring the level of contamination of surfaces in a room via…
* Contact plates - Surface agar is gently pressed onto the surface for 2-4 secs
* Surface swabs - Used to get samples from corners and curved surfaces
Explain the design features of a laminar flow cabinet
- Inward airflow through sash opening - Protects the user
- HEPA filtered downflow of air onto work surface - Protects protection from unfiltered incoming air (by pushing it down)
- Exhaust air is filtered by HEPA - Environmental protection
What class of biosafety is a Laminar flow hood
Class II
What are the application of grade A areas
High-risk operations such as…
* Handling sterile materials
* Aseptic connections
* Product filling
What are the applications of grade B areas
A clean environment used for…
* Aseptic preparation
* Filling
* Compounding processes
What are the applications of grade C rooms
A space used for less critical stages of sterile product manufacturing such as…
* Preparatiuon of solution to be sterilised
* Handling components
What can disturb laminar flow conditions in a LFA
- Sudden movements
- Excess equipment in hood -> obstruction
- Heat sources (e.g. bunsen burners)
What is the purpose of testing the inside of the cabinet for Filter integrity
To determine if HEPA filter consists of any leaks or faulty seals
What is the purpose of testing the inside of the cabinet for Air velocity
To determine if the air velocity complies with the standard and prevent ingress of dirty air
What can Antimicrobial preservatives be used for
- Oral liquid preparations
- Creams and lotions
- Eyedrops
- Injectables
- Nose & ear drops
What is AMP not used for
antimicrobial preservatives are not used for…
* Dry powders
* Tablets
* Capsules
* Ointments
