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Pathology 2 - Second Year BHMS

STERILIZATION AND DISINFECTION

STERILIZATION AND DISINFECTION

  1. Sterilization - the process of removing all forms of microbial life.
  2. Disinfection - the process of killing microorganisms on non-living surfaces.
  3. Asepsis - the practice of preventing the introduction of microorganisms into a wound or on a surface.
  4. Decontamination - the process of reducing the number of microorganisms to a safe level.
  5. Bactericidal agents - substances that kill bacteria.
  6. Bacteriostatic agents - substances that inhibit the growth of bacteria.

METHODS OF STERILIZATION

  1. Physical methods: a. Hot air oven b. Autoclave c. Dry heat sterilization d. Ethylene oxide sterilization e. Radiation sterilization f. Filtration sterilization

PHYSICAL METHODS OF STERILIZATION

  1. Hot air oven: a. Temperature: 160-170°C b. Time: 1-2 hours c. Used for heat-stable equipment and supplies
  2. Autoclave: a. Uses high-pressure steam b. Temperature: 120-130°C c. Time: 15-30 minutes d. Used for heat-sensitive equipment and supplies
  3. Dry heat sterilization: a. Temperature: 160-190°C b. Time: 2-4 hours c. Used for heat-stable equipment and supplies
  4. Ethylene oxide sterilization: a. Uses ethylene oxide gas b. Temperature: 30-50°C c. Time: 2-8 hours d. Used for heat-sensitive equipment and supplies

STERILIZATION USING HOT AIR OVEN

  1. Preheat the oven to 160-170°C.
  2. Place the equipment or supplies in a sterilization pouch.
  3. Seal the pouch and place it in the oven.
  4. Sterilize for 1-2 hours.
  5. Remove the pouch from the oven and let it cool.

STERILIZATION USING AUTOCLAVE

  1. Fill the autoclave with water to the recommended level.
  2. Place the equipment or supplies in a sterilization pouch.
  3. Seal the pouch and place it in the autoclave.
  4. Close the lid and set the timer according to the manufacturer's instructions.
  5. Sterilize for 15-30 minutes.
  6. Remove the pouch from the autoclave and let it cool.

PASTEURIZATION

  1. A process of killing microorganisms by heat.
  2. Used for dairy products and other food items.
  3. Temperature: 63-70°C
  4. Time: 30 minutes

CHEMICAL AGENTS OF STERILIZATION

  1. Ethanol
  2. Isopropanol
  3. Bleach
  4. Hydrogen peroxide
  5. Glutaraldehyde

CHARACTERISTICS OF DISINFECTANT

  1. Effective against a wide range of microorganisms.
  2. Should not be toxic or irritating to humans or animals.
  3. Should not be corrosive or damage surfaces.
  4. Should be easy to use and apply.
  5. Should be effective at a low concentration.

Sterilization and Disinfection

  1. Definition of Sterilization:

    • Process of destroying all forms of microbial life, including bacteria, viruses, fungi, and spores.
    • Requires a high degree of certainty that the object or surface is free from microorganisms.

  2. Definition of Disinfection:

    • A chemical process that destroys most microorganisms, but may not necessarily kill all bacteria, viruses, fungi, and spores.
    • Disinfectants are used to reduce the number of microorganisms on a surface.

  3. Definition of Asepsis:

    • State of being free from pathogens.
    • Maintenance of aseptic conditions is essential in medical, surgical, and laboratory procedures.

  4. Definition of Decontamination:

    • Process of removing or destroying pathogens from surfaces, equipment, or objects.
    • Decontamination methods include physical, chemical, and biological methods.

  5. Definition of Bactericidal Agents:

    • Substances that kill bacteria.
    • Bactericidal agents are used to disinfect surfaces and equipment.

  6. Definition of Bacteriostatic Agents:

    • Substances that inhibit the growth and reproduction of bacteria.
    • Bacteriostatic agents are used to prevent the growth of bacteria in certain situations.

Methods of Sterilization

  1. Physical Methods of Sterilization:

    • Hot air oven
    • Autoclaving
    • Dry heat sterilization
    • Ethylene oxide sterilization
    • Gamma radiation

  2. Hot Air Oven Sterilization:

    • Uses dry heat to kill microorganisms.
    • Temperature: 160°C - 170°C
    • Time: 2-4 hours
    • Used for heat-stable materials.

  3. Autoclave Sterilization:

    • Uses high-pressure steam to kill microorganisms.
    • Temperature: 121°C
    • Time: 15-20 minutes
    • Used for heat-stable materials.

  4. Pasteurization:

    • Process of heating liquids to kill microorganisms.
    • Temperature: 63°C - 72°C
    • Time: 30 minutes to several hours
    • Used for liquids, such as milk and juice.

Chemical Agents of Sterilization

  1. Germicides:

    • Substances that kill microorganisms.
    • Examples: phenol, formaldehyde.

  2. Disinfectants:

    • Substances that reduce the number of microorganisms.
    • Examples: bleach, hydrogen peroxide.

  3. Antiseptics:

    • Substances that prevent the growth of microorganisms on living tissues.
    • Examples: iodine, chlorhexidine.

Characteristics of Disinfectants

  1. Action:

    • Must kill or inactivate microorganisms.
    • Must be effective against a wide range of microorganisms.

  2. Stability:

    • Must be stable under various conditions, such as temperature and pH.
    • Must not degrade or break down over time.

  3. Toxicity:

    • Must be non-toxic to humans and animals.
    • Must not cause irritation or allergic reactions.

  4. Persistence:

    • Must remain effective for a reasonable period of time.
    • Must not break down or degrade quickly.

  5. Compatibility:

    • Must be compatible with the surface or material being disinfected.
    • Must not damage or discolor the surface.