Types of Sterilisation Flashcards
What is “sterile”?
Free from bacteria or other living micro-organisms and their spores.
What are 5 physical methods of sterilisation via heat?
Hot air oven
Red heat
Autoclave
Incineration
Boiling
What is a hot air oven effective against? What can it sterilise?
Effective against bacteria, viruses, moulds, and heat-resistant materials.
Can sterilise glassware, powders and metals.
What is red heat? What equipment can it be used on?
Sterilising via holding an instrument in a Bunsen’s flame until it becomes red-hot.
Can be used on incubation loops, wires, forceps, scissors and scalpels.
How does autoclaving kill microorganisms?
Coagulating their proteins, denaturing enzymes.
Which heat is more effective for sterilisation: moist or dry? Why?
Moist heat.
Sterilisation with moist heat requires temperatures above boiling.
What is an autoclave? What temperature does it reach?
A chamber which is filled with hot steam under pressure.
Reaches 121C at twice atmospheric pressure.
What is incineration? What is it used for?
Reducing materials to ashes via burning.
Used for disposable items and biological waste.
What is boiling? What can it be used to kill? What equipment can it be used on?
Heating water to 100C for 10-30 minutes
Kills most pathogenic organisms, viruses, bacteria, waterborne diseases. Will NOT kill spores.
Can be used on selective media and for home sterilising.
What are two other method of physical sterilising?
Mechanical: Microfiltration
Radiation: Ultraviolet, Gamma
What is microfiltration? What can it be used on?
Passing liquid through a microfiltration system, which separates micro-organisms and particles from liquid.
Can be used on liquid toxins, serums, sugars, and antibiotic solutions.
What is ultraviolet radiationg used to sterilise? How does it work?
Used to sterilise surfaces/rooms, air, water/wastewater, and food & beverage.
Breaks down certain chemical bonds and scrambles the structures of DNA, RNA, and other proteins.
How does Gamma radiation sterilise? What can it be used on?
Breaks down DNA and inhibits cell division. Can pass through equipment and deactivate any microorganisms present.
Medical devices, plastic, tissue allografts. Used for radiation therapy.
What are 4 gaseous chemical methods of sterilisation?
1) Ethylene oxide
2) Formaldehyde
3) Glutaraldehyde
4) Nitrogen Dioxide
What are 3 liquid chemical methods of sterilisation?
1) Hydrogen peroxide
2) Glutaraldehyde
3) Hypochlorite
