Sterilisation & Disinfection Flashcards
What is sterilisation?
The killing of ALL forms of microorganisms, including spores.
Sterilisation is distinct from disinfection, which does not eliminate spores.
What is disinfection?
Elimination or reduction of vegetative microorganisms, excluding spores.
Disinfection is often used in contexts where complete sterilisation is not necessary.
What are the routes through which infection can be introduced into an organism?
- Systemic: medicine, surgery, instruments, dressings, injectables
- Oral: consumption of foodstuffs or medicines
- Local: application of products such as droplets, inhalers, or suppositories
What is the importance of maintaining integrity during sterilisation or disinfection?
To prevent infection and preserve the characteristics of the item being sterilised or disinfected.
This is crucial in medical and laboratory settings.
What are the performance considerations for autoclaves?
- Wrapping of items
- Load pre-infection
- Packing of load
- Moisture
- Time
- Temperature
What is the required temperature and time for clean items in an autoclave?
121 degrees C for 15 minutes.
This is for clean items or media; waste requires higher temperatures.
What is the required temperature and time for waste in an autoclave?
134 degrees C for 30 minutes.
Why is moisture important in the autoclave process?
Dry air prevents sterilisation at autoclave temperatures.
What biological indicator is used for autoclave performance?
Use of spore-forming microorganisms such as bacillus subtilis (requires culture).
What physical parameters are monitored in autoclave performance?
Time, temperature, and pressure.
What chemical measures are used to check autoclave performance?
Autoclave tape
Browne tape
What type of indicator is used for hot oven performance?
Indicator tape specific for dry heat ovens.
What are the physical parameters monitored in hot oven performance?
Time, temperature, and pressure.
Fill in the blank: The host _______ refers to the microorganisms living in or on a host organism.
microbiome
True or False: Sterilisation eliminates all forms of microorganisms, while disinfection only reduces vegetative microorganisms.
True
What is the boiling point used in the boiling method for decontamination?
100°C
Does boiling kill endospores?
No
What are the two types of pasteurisation?
- Slow - 63-66°C x 30 minutes
- Rapid - 73°C x 15 seconds
Who is pasteurisation named after?
Louis Pasteur
What is membrane filtration?
Polymer films/membranes with microscopic pores
Viruses so small they can fit through filter though
What is the pore size range for membrane filtration?
- 0.1 μm
- 0.22 μm
- 0.45 μm
What pore size is required to filter yeast?
0.45 - 1.2 μm
What pore size is required to filter bacteria?
0.2 μm
What pore size is required to filter viruses and mycoplasmas?
0.01 - 0.1 μm
What are some applications of membrane filters?
- Heat sensitive products
- Laboratory and industrial purposes (e.g. filtered milk)
What are some disadvantages of membrane filtration?
- Saturation (clogging)
- Product retention
What is depth filtration used for?
- Clarifying bulk products
- Reducing bio-burden
- Filtering viruses (nanofiltration)
- Reducing endotoxin
What is a key consideration for filtration in sterilisation?
Filtration alone is not sufficient when sterilisation by other means in the final container is possible
What is the recommended pore size for filters when sterilising solutions?
0.22 micron or less
What should be done if it is not possible to use heat for terminal sterilisation?
Use a second titration
What is ethylene oxide gas (ETO) used for?
Chemical sterilisation for items that cannot be sterilised by irradiation or moist heat
What percentage of medical devices in the USA are sterilised with ETO?
Approximately 50%
What are some hazards associated with ETO?
- Carcinogenic
- Teratogenic
- Mutagenic
- Can induce spontaneous abortion
- Volatile and Explosive
How does ETO work in sterilisation?
By alkylation of protein and DNA
What does disinfection involve?
Cleansing a wound or a room (surface/object), removing dirt and potentially infectiour organisms from an area/ object.
What are antiseptics required to do?
- Clean dirt
- Kill microorganisms
- Be non-toxic to tissues
What are key considerations in sterilisation and disinfectant procedures?
Dose and contact time
Fill in the blank: The amount and time of the agent/method applied to ensure microorganisms are inactivated or killed is known as _______.
[dose and contact time]
