Sterilization Techniques and Methods
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What is the primary mechanism of action for moist heat sterilization?

  • Coagulating proteins in microorganisms (correct)
  • Disrupting the DNA of pathogens
  • Oxidizing cellular components
  • Destroying the cell membrane of microorganisms

At what temperature is milk typically pasteurized using the Holder method?

  • 72°C for 15-20 seconds
  • 56°C for one hour
  • 100°C for 10 minutes
  • 63°C for 30 minutes (correct)

Which of the following correctly describes the use of boiling in sterilization?

  • It guarantees the destruction of all endospores
  • It can kill vegetative forms of bacterial pathogens (correct)
  • It is effective against all types of viruses reliably
  • It is a preferred method for sterilizing vaccines

What is a key feature of the autoclave designed by Charles Chamberland?

<p>It uses steam under pressure for sterilization (D)</p> Signup and view all the answers

What temperature and duration are generally used for a vaccine preparation in a hot water bath?

<p>60°C for 1 hour (B)</p> Signup and view all the answers

What is the primary action of hydrogen peroxide as an oxidizing agent?

<p>Inhibiting enzymatic activity by attacking sulfhydryl groups (B)</p> Signup and view all the answers

Which of the following is a disadvantage of metallic salts used as disinfectants?

<p>They have limited fungicidal activity. (D)</p> Signup and view all the answers

What types of surfaces can ethylene oxide effectively sterilize?

<p>Glass, metal, paper surfaces, and organics (A)</p> Signup and view all the answers

Which filter types are commonly used for sterilization by filtration?

<p>Candle filters, sintered glass filters, and membrane filters (B)</p> Signup and view all the answers

What type of radiation is considered suitable for rapid mass sterilization?

<p>Non-ionizing radiation such as UV rays (B)</p> Signup and view all the answers

What is the primary method by which dry heat sterilization kills microorganisms?

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

At what temperature is a holding period of 2 hours most effective for dry heat sterilization?

<p>160°C (D)</p> Signup and view all the answers

Which of the following agents is NOT classified as a chemical agent for sterilization?

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

What type of filtration is used for liquids?

<p>Water filtration (D)</p> Signup and view all the answers

Which treatment method is specifically described as ideal for destroying contaminated materials?

<p>Flaming/incineration (D)</p> Signup and view all the answers

Which of the following methods involves using a Bunsen flame?

<p>Incineration (D)</p> Signup and view all the answers

What is the range of temperatures that a dry oven operates within for sterilization?

<p>50°C to 300°C (B)</p> Signup and view all the answers

Which chemical agent is specifically used for inanimate objects?

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

At what temperature and duration is flash sterilization achieved?

<p>132º for 3 minutes (B)</p> Signup and view all the answers

Which of the following chemical agents is NOT effective against spores?

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

Which statement correctly describes the action of hydrogen peroxide?

<p>Limited by the organism's ability to produce catalase (D)</p> Signup and view all the answers

What is the recommended concentration of alcohol for disinfection purposes?

<p>60-90% in water (A)</p> Signup and view all the answers

Which of the following uses formaldehyde?

<p>To preserve anatomical specimens (D)</p> Signup and view all the answers

What is the primary goal of sterilization?

<p>Removing all microorganisms including their spores. (D)</p> Signup and view all the answers

Chlorine compounds are primarily utilized for which purpose?

<p>Disinfecting water supplies (D)</p> Signup and view all the answers

Which method is commonly used for sterilization of surgical instruments that can be damaged by moist heat?

<p>Ethylene oxide gas exposure. (D)</p> Signup and view all the answers

What is a key property of phenolic derivatives in antisepsis?

<p>They possess microbicidal properties (A)</p> Signup and view all the answers

What does disinfection achieve?

<p>It kills many but not all microorganisms, including some bacterial spores. (B)</p> Signup and view all the answers

Iodine solutions are known for what type of action against bacteria?

<p>Moderate action against spores and actively bactericidal (B)</p> Signup and view all the answers

What physical condition is required for autoclaving?

<p>Steam at 121°C under a pressure of 15 lb/in² for 15 minutes. (B)</p> Signup and view all the answers

Which process involves the mechanical removal of microbes from surfaces?

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

What was a significant advancement in the mid-1800s to prevent surgical infections?

<p>Aseptic techniques developed by Lister. (C)</p> Signup and view all the answers

Which of the following is a method of microbial growth control?

<p>Damage to nucleic acids and alteration of membrane permeability. (D)</p> Signup and view all the answers

What does a bacteriostatic agent do?

<p>Inhibits the growth of bacteria (B)</p> Signup and view all the answers

What were the death rates due to nosocomial infections in surgeries prior to modern aseptic techniques?

<p>10%. (D)</p> Signup and view all the answers

Which of the following is NOT considered an antiseptic?

<p>Corrosive phenol-containing disinfectants (D)</p> Signup and view all the answers

What is a characteristic of bacterial spores that makes sterilization challenging?

<p>They are highly resistant to environmental factors. (A)</p> Signup and view all the answers

What is considered the absence of significant contamination?

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

Which process specifically targets the destruction of vegetative pathogens?

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

What term describes an agent that kills spores?

<p>Sporicidal (D)</p> Signup and view all the answers

What is the difference between antiseptics and disinfectants?

<p>Disinfectants can be corrosive, while antiseptics must be safe for skin. (A)</p> Signup and view all the answers

Flashcards

Sterilization

The process of completely eliminating all microorganisms, including highly resistant bacterial spores, from an object or surface.

Disinfection

The killing or removal of most microorganisms, but not necessarily all, including bacterial spores, from an object or surface.

Antisepsis

The process of reducing the number of microbes on living tissue to a safe level.

Alternation of membrane permeability

A type of microbial growth control that damages the cell membrane, allowing cell contents to leak out.

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Damage to proteins

A type of microbial growth control that disrupts the structure and function of proteins, making them unable to perform their roles.

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Damage to nucleic acids

A type of microbial growth control that targets the cell's genetic material, preventing the cell from replicating or functioning correctly.

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Autoclaving

A method of sterilization that uses high temperatures and pressure to kill all microorganisms, including spores. Commonly used for medical instruments.

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Ethylene oxide gas sterilization

A method of sterilization that uses a gas to kill all microorganisms. Primarily used for materials that cannot be sterilized by heat.

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Sanitization

Any cleansing technique that mechanically removes microbes. It doesn't necessarily kill them.

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Degermation

Mechanically removing microbes from a surface, such as skin. This can involve methods like surgical hand scrubbing or wiping with alcohol.

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Sepsis

The presence of harmful bacteria in the blood or tissues.

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Asepsis

The absence of significant contamination by microorganisms.

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Dry Heat Sterilization

A method of sterilization using dry heat in an oven to kill microorganisms. It's typically used for items that can withstand high temperatures, like surgical instruments, glassware, and powders.

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Chemical Sterilization

A method of sterilization using chemicals to kill all microorganisms. This is often used on items that can't be sterilized with heat, like medical devices made of plastic.

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Pasteurization

A method of sterilizing liquids by heating them to a specific temperature for a set amount of time, killing most harmful bacteria. It's often used for milk and other beverages.

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Ionizing Radiation Sterilization

A method of sterilizing using ionizing radiation, like X-rays or gamma rays, to kill all microorganisms. This method is often used for medical supplies and food preservation.

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Ultraviolet (UV) Radiation Sterilization

A method of sterilization using ultraviolet (UV) light to kill microorganisms. It's often used to sterilize surfaces, air, and water.

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Filtration

A physical removal method using filters to separate microbes from liquids or air. This is often used to purify water or sterilize air in hospitals.

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Flaming/Incineration

A method of sterilizing by using heat, like a Bunsen burner or an incinerator, to kill all microorganisms. Used for sterilizing equipment that can withstand high temperatures.

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Autoclave

A moist heat sterilization method that uses steam under pressure to kill all microorganisms, including spores.

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Boiling for sterilization

Kills most vegetative bacteria, but may not kill all spores or resistant viruses. This method uses water boiling at 100 degrees Celsius.

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Steam sterilization at atmospheric pressure

A sterilization method using steam at atmospheric pressure. Less effective than autoclaving, but still useful for killing vegetative bacteria.

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Sterilization below 100 degrees Celsius

A method of sterilization that involves heating materials to temperatures below 100 degrees Celsius, often using an inspissator. Effective against some bacteria, but not highly resistant ones.

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What is sterilization?

The process of killing all microorganisms, including spores, using high pressure and heat.

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What is disinfection?

The process of killing or removing most, but not all, microorganisms from a surface.

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What is antisepsis?

Applying chemical agents to living tissue to kill or inhibit the growth of microorganisms.

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What is the ideal concentration of alcohol for disinfection?

Alcohol's effectiveness in killing microorganisms is highest when it's diluted to a certain concentration.

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Why are aldehydes used as disinfectants?

Aldehydes are effective disinfectants that can kill a wide range of microorganisms, including spores.

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What are halogens used for in disinfection?

Halogens like iodine and chlorine are known for their disinfecting power, especially against bacteria.

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What are phenols used for?

Phenols are potent disinfectants derived from coal tar and are often used in hospitals.

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What limits hydrogen peroxide's disinfecting power?

Hydrogen peroxide's effectiveness as a disinfectant can be limited by an enzyme some organisms produce.

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How does Hydrogen peroxide work?

Hydrogen peroxide is a chemical that breaks down harmful substances like bacteria and viruses by damaging their internal parts. It works by reacting with a molecule called a sulfhydryl group, which is essential for many enzymes that bacteria need to survive. This interference with enzymes effectively stops the bacteria's growth and metabolism.

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What is Ethylene oxide gas used for?

Ethylene oxide gas, a colorless and sweet-smelling gas, is incredibly effective at killing all types of microorganisms, including viruses and resistant spores. It's widely used for sterilizing medical equipment like heart-lung machines, respirators, and surgical instruments, as well as other items like books and clothing.

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How do metallic salts like silver, copper, and mercury work as disinfectants?

Salts of silver, copper, and mercury are used as disinfectants by disrupting the structure of proteins vital for bacterial survival. They are more effective at inhibiting bacterial growth (bacteriostatic) than directly killing them (bactericidal). They also have limited effects on fungi.

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How does filtration sterilize heat-sensitive liquids?

Sterilization by filtration involves removing bacteria from liquids that can't withstand high temperatures, such as blood serum, sugar solutions, and antibiotic solutions. This process utilizes various filters, including candle filters, asbestos filters, sintered glass filters, and membrane filters, which trap the bacteria.

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How does non-ionizing radiation like UV rays sterilize?

Non-ionizing radiation, like UV rays, uses longer wavelengths of light to primarily generate heat. This heat energy can be used to kill microorganisms rapidly, making it ideal for sterilizing prepackaged syringes and catheters. It is considered a hot air sterilization method.

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Study Notes

Sterilization, Disinfection, and Antisepsis

  • Microorganisms cause contamination, infection, and decay
  • Early civilizations used methods like salting, smoking, pickling, and sun exposure to preserve food
  • Aseptic techniques were developed in the mid-1800s to prevent contamination of surgical wounds
  • Nosocomial infections caused significant patient deaths before aseptic techniques
  • Methods of microbial growth control include altering membrane permeability, damaging proteins, and damaging nucleic acids
  • Prions are the most resistant, followed by bacterial spores, mycobacteria, and cysts of protozoa
  • Viruses with lipid envelopes are the least resistant

Definition of Sterilization

  • Sterilization is the process of eliminating all microorganisms, including spores.
  • It is essential for surgical procedures and other medical applications where contamination cannot be tolerated.

Methods of Sterilization

  • Physical Agents:

    • Heat: Dry heat (e.g., incineration, dry oven) and moist heat (e.g., steam under pressure, autoclave). Dry heat sterilization is more powerful than moist heat sterilization.
      • The autoclave works under pressure (121°C or 132°C for various time intervals)
      • Temperature is controlled by a thermostat and double-walled insulation conserves energy.
      • Autoclaves are either vertical or horizontal cylinders with an opening for placing items to be sterilized. A pressure gauge measures the pressure, and a safety valve allows steam to escape
    • Radiation: Ionizing radiation (e.g., X-rays, gamma rays, cosmic rays) and non-ionizing radiation (e.g., UV rays).

  • Chemical Agents:

    • Gases: Ethylene oxide, hydrogen peroxide vapor, and others
    • Liquids: Various chemical solutions
      • Alcohols like ethanol or isopropyl alcohol frequently used as disinfectants, are often used in concentrations between 60%-90%
      • They also effectively disinfect clinical thermometers.
      • They can effectively disinfect the skin prior to venipunctures.
    • Other Methods: Various chemical methods are employed for sterilization
      • Formaldehyde and glutaraldehyde are frequently used as disinfectants.
      • Phenols are employed to disinfect various surfaces and objects in hospitals.

  • Mechanical Removal: Filtration (air and liquids)

    • Candle, Asbestos, and sintered glass filters are used for sterilization.

Methods of Disinfection

  • Disinfectants kill many microorganisms but not all
  • Antiseptics are less toxic chemical solutions
  • Often, disinfectants and antiseptics are used together to ensure proper procedures

Principles of effective disinfection

  • Concentration of disinfectant
  • Organic matter
  • pH
  • Time

Terminology

  • Degermation: Mechanical removal of microbes
  • Sepsis: Bacterial contamination
  • Asepsis: The absence of significant contamination
  • Bactericidal: Kills bacteria
  • Bacteriostatic: Inhibits bacteria growth but doesn't kill
  • Sporicidal: Kills spores
  • Sterilization: Kills all organisms, including spores
  • Disinfection: Kills many organisms (not all), not spores
  • Antiseptic: Disinfectant use directly on exposed body surfaces
  • Sanitization: Mechanical removal of microbes

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Sterilization, Disinfection, and Antisepsis PDF

Description

Test your knowledge on various sterilization techniques, including moist heat sterilization, pasteurization methods, and the use of radiation. This quiz explores key concepts such as the functioning of autoclaves, chemical agents for disinfecting, and filtration methods. Perfect for students in microbiology or healthcare fields.

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