Sterilization Techniques and Methods

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Questions and Answers

What is the primary mechanism by which ultrasonic waves contribute to sterilization?

  • Introducing a biocide into the solution
  • Creating a chemical reaction that destroys microorganisms
  • Directly heating the solution to kill microbes
  • Producing alternating compressive and tensile forces that form and collapse cavities, removing microorganisms (correct)

Fractional sterilization is effective in killing all spores, including those of thermophiles and anaerobes.

False (B)

Which of the following is NOT a gaseous chemical agent used for sterilization?

  • Ethylene oxide
  • Formaldehyde
  • Nitrogen dioxide
  • Hydrogen Peroxide (correct)

What is the limitation of filtration as a method of sterilization?

<p>It is ineffective for small viruses.</p> Signup and view all the answers

Liquid sterilization is more effective than gaseous sterilization.

<p>False (B)</p> Signup and view all the answers

In chemical sterilization, objects are exposed to gas in a closed, heated and ______ chamber.

<p>pressurized</p> Signup and view all the answers

What is the primary goal of sterilization?

<p>To completely remove all forms of microorganisms from a surface (C)</p> Signup and view all the answers

Match the sterilization techniques with their primary advantage:

<p>Heat Sterilization = Efficient and reliable for most materials Filtration = Ideal for heat-sensitive liquids and gases Radiation = Effective for disposable medical tools and surfaces Sound Wave Vibration = Non-invasive; useful for cleaning delicate instruments</p> Signup and view all the answers

Name two common liquid chemical agents used for sterilization.

<p>hydrogen peroxide, glutaraldehyde</p> Signup and view all the answers

Why is heat sterilization not suitable for all materials?

<p>It may cause degradation of heat-sensitive materials. (A)</p> Signup and view all the answers

Sterilization using _____ is effective for heat- and moisture-sensitive materials.

<p>gas</p> Signup and view all the answers

Disinfection and sterilization have the exact same meaning and outcome.

<p>False (B)</p> Signup and view all the answers

Match the sterilization technique with its description:

<p>Heat Sterilization = Uses an autoclave to sterilize materials Filtration = Removes bacteria and particulates from heat-sensitive liquids Radiation = Uses gamma radiation to sterilize disposable items Vibration = Uses ultrasonic cleaners to clean delicate instruments Fractional Sterilization = Sterilizes heat sensitive material over several days Gas Sterilization = Uses ethylene oxide gas to sterilize plastic items</p> Signup and view all the answers

What is the main principle behind how an autoclave works?

<p>producing steam under pressure</p> Signup and view all the answers

Radiation sterilization is ideal for heat-sensitive materials.

<p>True (A)</p> Signup and view all the answers

Which sterilization method is most appropriate for plastic catheters?

<p>Gas Sterilization (C)</p> Signup and view all the answers

Moist heat sterilization is also known as _________ sterilization.

<p>steam</p> Signup and view all the answers

What is the main difference between gaseous and liquid chemical sterilization?

<p>The physical state of the chemical sterilizing agent.</p> Signup and view all the answers

Which of the following is a method of physical sterilization?

<p>Autoclaving (C)</p> Signup and view all the answers

Residual chemicals are a potential disadvantage of gas sterilization.

<p>False (B)</p> Signup and view all the answers

Match the sterilization method with its description:

<p>Autoclaving = Uses steam under pressure Filtration = Removes microorganisms by size exclusion Radiation = Uses electromagnetic energy to damage genetic material Chemical Sterilization = Uses agents to eliminate microorganisms</p> Signup and view all the answers

What is one advantage of using liquid sterilization?

<p>useful for heat-sensitive materials</p> Signup and view all the answers

Which of these is NOT a type of physical sterilization?

<p>Cold Sterilization (C)</p> Signup and view all the answers

What is the primary mechanism of microbial death in an autoclave?

<p>Coagulation of proteins (D)</p> Signup and view all the answers

An autoclave typically operates at a temperature of 121-134℃ and a pressure of _______.

<p>15psi</p> Signup and view all the answers

Dry heat sterilization is suitable for objects sensitive to moisture.

<p>True (A)</p> Signup and view all the answers

Name one type of radiation used in sterilization.

<p>Ultraviolet radiation or Gamma rays or X-rays</p> Signup and view all the answers

Which of the following is NOT a step in using an autoclave?

<p>Filtration (A)</p> Signup and view all the answers

In radiation sterilization, ultraviolet light is absorbed by the microbial cell's _________.

<p>nucleic acids</p> Signup and view all the answers

What is the frequency range of sound waves used in sound wave sterilization?

<p>20-40 kHz (D)</p> Signup and view all the answers

Microfiltration uses a membrane with large pores to remove microbes.

<p>False (B)</p> Signup and view all the answers

Match the sterilization method with its mechanism:

<p>Autoclave = Coagulation of proteins Dry Heat Sterilization = Denaturation and Lysis of proteins, oxidative damage Filtration = Mechanical removal of microbes Radiation Sterilization = Formation of pyrimidine dimers or oxidation of cellular components Sound Waves = Sound waves applied across the fluid to be sterilized</p> Signup and view all the answers

Flashcards

Sterilization

The process of eliminating all microorganisms from a surface.

Moist Heat Sterilization

A method using heat to sterilize, typically in an autoclave.

Autoclave

A device that uses pressurized steam for sterilization.

Filtration

A method that uses filters to remove microorganisms from liquids or gases.

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Radiation Sterilization

A method that uses radiation to kill microorganisms.

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Cold Sterilization

Sterilization that doesn't require heat.

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Chemical Sterilization

Sterilization using chemicals to kill microorganisms.

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Gaseous Sterilization

A method that uses gases to sterilize objects.

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Dry Heat Sterilization

Dry heat sterilization is used for objects sensitive to moisture. High temperatures denature and break down microbial proteins, leading to cell death.

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Filtration Sterilization

This method uses filters with tiny pores to trap and remove microorganisms from liquids. The filter acts as a barrier.

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Ultraviolet Radiation Sterilization

Ultraviolet (UV) radiation damages microbial DNA by forming pyrimidine dimers, preventing proper replication and leading to cell death.

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Ionizing Radiation Sterilization

Ionizing radiation, like gamma rays and X-rays, produces reactive oxygen species that damage microbial cells, leading to their death.

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Sonication Sterilization

High-frequency sound waves disrupt cell structures and lead to cell death.

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High-Pressure Processing (HPP)

High-pressure processing (HPP) uses extremely high pressure to destroy microorganisms in food products.

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Autoclave Sterilization

This mechanical sterilization method uses a sealed chamber and steam under pressure to kill microorganisms.

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Ultrasonic Sterilization

A method of sterilization using ultrasonic waves that create cavities (bubbles) in the liquid. The rapid collapse of these cavities generates high energy and pressure, killing microorganisms.

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Fractional Sterilization (Tyndallization)

A repeated heat sterilization method used for heat-sensitive media like gelatin or sugar. It involves multiple exposures to heat, allowing time for spores to germinate and then be killed.

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Heat Sterilization

A sterilization method using high temperatures to kill all forms of microorganisms, including spores. This is effective for heat-resistant materials, but can damage heat-sensitive materials.

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Sound Wave Vibration

A sterilization method using sound waves to vibrate instruments, dislodging dirt and microorganisms. This method is useful for cleaning delicate instruments, though its sterilization capabilities are limited.

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Fractional sterilization

A type of sterilization where materials are exposed to specific heat intervals to kill microorganisms. It's often used for sterilizing heat-sensitive media, requiring multiple cycles.

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Liquid chemical sterilization

A method that uses chemical agents like glutaraldehyde or hydrogen peroxide to sterilize objects. This option is best for materials that cannot withstand heat or radiation sterilization.

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Liquid sterilization

A technique used to sterilize materials by immersing them in a liquid chemical solution that kills all microorganisms, including spores. This method is less effective than gaseous sterilization and ideal for lower levels of contamination.

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Study Notes

Sterilization Techniques

  • Sterilization is the removal of all microorganisms from a surface or object.
  • This differs from disinfection, where only the reduction of microorganisms occurs.
  • By removing all microorganisms, sterilization creates a sterile or aseptic environment.

Types of Sterilization

  • Sterilization can be categorized into physical and chemical methods.

Physical Methods

  • Heat Sterilization: Involves killing microorganisms using heat.

    • Moist Heat Sterilization (Autoclaving): Uses steam under pressure. Water is heated to 121-134°C (at 15 psi pressure), causing proteins in microorganisms to coagulate and be killed. This is one of the most effective sterilization methods for many materials.

      • Steps in using Autoclave include; Preparation, Loading, Setting parameters, Starting the cycle, Cooling and Venting, Unloading and Post sterilization Care.

    • Dry Heat Sterilization: Is used for objects sensitive to moisture (e.g., glass equipment, metal instruments). Dry heat is applied to denature and damage proteins in microorganisms, leading to their death. Dry Heat methods include incineration, hot air ovens and flaming techniques.

  • Filtration: A physical method that uses a filter with small pores to remove microorganisms from liquids or gases. Common in microbiology laboratories. Methods used include sieving, adsorption and trapping.

  • Radiation Sterilization: Includes exposing surfaces or objects to different types of radiation (ultraviolet and ionizing; ionizing includes x-rays and gamma rays). These methods damage the DNA, leading to microbial death.

    • Non-Ionizing Radiation: UV radiation is absorbed by nucleic acids in microorganisms, interfering with their replication and causing cell death.

    • Ionizing Radiation: Damage to DNA results from gamma and X-rays causing reactive oxygen species to oxidize cell components.

  • Sound Wave Vibration: Sonix sound waves with frequencies of 20-40 kHz are applied to a fluid. This creates cavitation (compressive and tensile forces forming cavities) that suddenly collapse, creating microscopic voids that remove the microorganisms from the fluid or container.

  • Fractional Sterilization: Used for products that cannot withstand other sterilization techniques. This method involves exposing the product to a high temperature (e.g., boiling) for a period multiple times over several days, allowing time for microbial spores to germinate to be killed by subsequent heat cycles, resulting in a higher chance of killing all microbial species.

Chemical Methods

  • Gaseous Sterilization: The object is subjected to sterilant gases within a sealed chamber. The agents commonly used in this process include ethylene oxide, formaldehyde, nitrogen dioxide and ozone.

  • Liquid Sterilization: The sterilization process involves immersing materials in a liquid sterilant. Chemical agents used for this method include hydrogen peroxide, glutaraldehyde and hypochlorites solution. Liquid immersion is less effective than gaseous sterilants.

Advantages and Disadvantages of Sterilization Methods

  • Each sterilization method has its own sets of advantages and disadvantages, the choice of sterilization technique depends on the properties of the materials to be sterilized.

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