Podcast
Questions and Answers
What is sterilization defined as?
What is sterilization defined as?
- The elimination of only vegetative forms of microorganisms
- The removal of visible soil from surfaces
- The process of removing germs from living tissue
- The complete elimination of microbial life including spores (correct)
Antisepsis involves the disinfection of inanimate objects.
Antisepsis involves the disinfection of inanimate objects.
False (B)
Name a physical method of sterilization.
Name a physical method of sterilization.
Thermal methods, Radiation methods, or Filtration methods
____________ is defined as the removal of pathogenic microorganisms from objects to make them safe to handle.
____________ is defined as the removal of pathogenic microorganisms from objects to make them safe to handle.
Which of the following is a purpose of sterilization in food processing?
Which of the following is a purpose of sterilization in food processing?
Match the terms with their definitions:
Match the terms with their definitions:
Cleaning is the same as sterilization.
Cleaning is the same as sterilization.
What does the term 'germicide' refer to?
What does the term 'germicide' refer to?
What temperature and duration is typically used during the heat treatment for sterilization over three days?
What temperature and duration is typically used during the heat treatment for sterilization over three days?
Endospores are destroyed during the heat treatments on the first day.
Endospores are destroyed during the heat treatments on the first day.
What is placed inside the autoclave to indicate the success of the sterilization process?
What is placed inside the autoclave to indicate the success of the sterilization process?
To achieve sterilization, a typical pressurised temperature of _____ °C is required.
To achieve sterilization, a typical pressurised temperature of _____ °C is required.
Match the following sterilization methods with their characteristics:
Match the following sterilization methods with their characteristics:
What is the purpose of placing materials in an incubator at 37 °C during the sterilization method described?
What is the purpose of placing materials in an incubator at 37 °C during the sterilization method described?
The sterilization process can take less than 10 minutes at 121 °C.
The sterilization process can take less than 10 minutes at 121 °C.
What can occur if the autoclave is opened before it has cooled down to safe temperatures?
What can occur if the autoclave is opened before it has cooled down to safe temperatures?
What is the primary mechanism for dry heat sterilization?
What is the primary mechanism for dry heat sterilization?
Dry heat sterilization is more effective than moist heat sterilization at removing water content.
Dry heat sterilization is more effective than moist heat sterilization at removing water content.
What temperature and duration are required for effective dry heat sterilization of glass equipment?
What temperature and duration are required for effective dry heat sterilization of glass equipment?
The process known as __________ uses boiling water to sterilize, but does not effectively kill heat resistant bacteria.
The process known as __________ uses boiling water to sterilize, but does not effectively kill heat resistant bacteria.
Which sterilization method effectively uses steam at a temperature higher than 100°C?
Which sterilization method effectively uses steam at a temperature higher than 100°C?
Match the sterilization method with its description:
Match the sterilization method with its description:
Flame sterilization is suitable for sterilizing surgical instruments.
Flame sterilization is suitable for sterilizing surgical instruments.
List two items that can be sterilized using dry heat methods.
List two items that can be sterilized using dry heat methods.
What is the primary purpose of an autoclave in microbiological practice?
What is the primary purpose of an autoclave in microbiological practice?
Autoclaves can effectively kill spores at temperatures above 100 C.
Autoclaves can effectively kill spores at temperatures above 100 C.
Name one method used to monitor the efficacy of autoclaves.
Name one method used to monitor the efficacy of autoclaves.
The main cause of cell death from UV radiation is the formation of ______ in nucleic acids.
The main cause of cell death from UV radiation is the formation of ______ in nucleic acids.
Match the sterilization methods with their characteristics:
Match the sterilization methods with their characteristics:
What is a disadvantage of UV radiation in sterilization?
What is a disadvantage of UV radiation in sterilization?
What change occurs to heat-sensitive chemicals used in autoclaves to indicate proper sterilization?
What change occurs to heat-sensitive chemicals used in autoclaves to indicate proper sterilization?
Gamma rays are not suitable for deep penetration in sterilization processes.
Gamma rays are not suitable for deep penetration in sterilization processes.
What is a disadvantage of the sterilisation of disposable needles and syringes?
What is a disadvantage of the sterilisation of disposable needles and syringes?
Filtration can be used for both solids and liquids.
Filtration can be used for both solids and liquids.
What is the ideal pore size for a filter to retain bacteria?
What is the ideal pore size for a filter to retain bacteria?
A 50-70% aqueous solution of ______ has excellent antiseptic properties.
A 50-70% aqueous solution of ______ has excellent antiseptic properties.
Match the following types of filters with their characteristics:
Match the following types of filters with their characteristics:
Which of the following is NOT an advantage of filtration?
Which of the following is NOT an advantage of filtration?
Autoclaving is generally more expensive than filtration for sterilisation.
Autoclaving is generally more expensive than filtration for sterilisation.
Name one chemical method of sterilisation.
Name one chemical method of sterilisation.
Study Notes
Sterilization Definition
- Complete elimination of all forms of microbial life including vegetative and spore forms.
Disinfection vs. Sterilization
- Disinfection: Eliminates vegetative forms of microorganisms, except bacterial spores, from inanimate objects.
- Sterilization: Eliminates all forms of microbial life, including spores, rendering a material sterile.
Antisepsis vs. Decontamination
- Antisepsis: Removal of germs from living tissue or skin (e.g., patient's skin or healthcare worker's hands) to reduce the number of transient microbes.
- Decontamination: Removal of pathogenic microorganisms from objects to make them safe to handle.
Germicide vs. Cleaning
- Germicide: Agent that destroys germs, including antiseptics and disinfectants. This term is often categorized by the specific type of microorganism it targets (e.g., virucide, fungicide, bactericide, sporicide, tuberculocide).
- Cleaning: Removal of visible soil (organic and inorganic materials) from surfaces and objects to achieve a minimum reduction of at least 1 log CFU (colony-forming unit) of microorganisms.
Sterilization Uses
- Food processing: Destroying harmful microbes that cause food spoilage.
- Medical uses: Sterilizing surgical instruments to prevent infections.
- Microbiology: Isolating, purifying, and growing microorganisms.
Physical Methods of Sterilization
- Thermal Methods (Heat):
- Dry Heat Sterilization:
- Hot Air Oven: 160°C for 1 hour or 180°C for 30 minutes. Used for glassware, cotton-plugged glassware, heat-resistant chemicals, inoculation needles, glass slides, tube mouths, and surgical instruments.
- Flaming: Used to sterilize inoculation needles, glass slides, and tube mouths.
- Moist Heat Sterilization:
- Boiling: Simplest and oldest method using moist heat, but does not sterilize because endospore-forming bacteria can survive in boiling water (100°C).
- Tyndallisation (Intermittent Sterilization): Involves heating at 100°C for 20 minutes for three consecutive days with incubation periods in between. This method targets vegetative forms on the first day, allowing endospores to germinate during incubation. The second and third days of heating destroy the germinated endospores. Used for protein media, skim milk agar, and polysaccharides.
- Autoclaving: The most effective moist heat sterilization method. Uses dry saturated steam at 121°C under 1.1 kg/cm2 pressure for 15-20 minutes. This combination of heat and pressure quickly destroys most microbes and is the preferred method for sterilizing most materials used in laboratory and medical settings.
- Radiation Methods:
- UV (Ultraviolet) Irradiation: Very strong germicidal effect around 265 nm wavelength, damaging DNA by forming pyrimidine dimers. Used in hospitals and labs for surface and air decontamination, but penetration is limited by glass, dirt films, water, and other substances.
- Gamma Ray Sterilizer: Uses gamma rays (high-energy ionizing radiation) from radioactive nuclides (e.g., 60Co) to sterilize items like disposable needles, syringes, bandages, medicines, and certain food (e.g., spices). Penetrates well, but requires special precautions due to its scattering properties.
- Dry Heat Sterilization:
- Filtration Methods: For liquids and gases that cannot be heated. Involves passing a fluid through a filter with a pore size that traps microbes.
Types of Filters
- Membrane Filters: Thin, made of cellulose.
- Seitz Filters: Made of asbestos.
- Sintered Glass Filters: Alternative to Seitz filters, made of glass.
- Candle Filters: Made of clay-like mud.
Advantages of Filtration
- Relatively inexpensive (except for small pore sizes).
- Filters do not clog easily.
- Suitable for heat-sensitive liquids.
- Can filter large volumes quickly.
Disadvantages of Filtration
- Only works on liquids and gases.
- Autoclaving is usually cheaper than replacing filters.
- Glass filters are brittle.
- Membrane filters rupture easily.
- Sietz filters can absorb the solution.
- Clogging can occur.
- Long process.
Chemical Methods of Sterilization
- Alcoholic: 50-70% aqueous solutions are excellent antiseptics.
- Halogens:
- Hydrogen Peroxide:
- Phenol:
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Description
Explore the concepts of sterilization, disinfection, and antisepsis through our quiz. Test your knowledge of the differences between these essential microbial control practices and their applications in healthcare settings. Learn how contamination is managed to ensure safety.
