Sterilization and Disinfection Quiz
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Questions and Answers

What is the primary characteristic of High Level Disinfection (HLD)?

  • It is effective only against vegetative bacteria.
  • It allows a small number of bacterial endospores to remain. (correct)
  • It kills high numbers of bacterial spores.
  • It destroys all microorganisms without exceptions.

    • What type of device must undergo High Level Disinfection?

  • Semi-critical ultrasound probes. (correct)
  • All disinfectants must undergo HLD.
  • Devices that contact sterile tissue only.
  • Non-critical instruments.

    • Which statement is true regarding the effectiveness of High Level Disinfectants over time?

  • They are effective only on surfaces with no visible blood.
  • They remain effective indefinitely once opened.
  • Their strength diminishes rapidly after being mixed. (correct)
  • They require over 24 hours of contact to disinfect.

    • Which level of disinfection is referred to as 'hospital disinfectants'?

    <p>Low Level Disinfection</p> Signup and view all the answers

    What is the purpose of the Spaulding Classification?

    <p>To stratify the risk of infection transmission.</p> Signup and view all the answers

    What is the primary mechanism by which sunlight inhibits microbial activity?

    <p>Ultraviolet rays</p> Signup and view all the answers

    Which method of sterilization is considered the most reliable for heat-resistant articles?

    <p>Moist heat</p> Signup and view all the answers

    How does the presence of organic material affect the sterilization process?

    <p>Increases the time required for sterilization</p> Signup and view all the answers

    What is the term that describes the minimum time required to kill microorganisms at a specified temperature?

    <p>Thermal death time</p> Signup and view all the answers

    In which scenario is dry heat more effective than moist heat?

    <p>For protein denaturation</p> Signup and view all the answers

    Which of the following factors is NOT considered when determining the effectiveness of heat as a sterilization method?

    <p>Size of the container</p> Signup and view all the answers

    What happens to the required sterilization time as the temperature increases?

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

    Which type of heat requires a higher temperature to kill microorganisms compared to moist heat?

    <p>Dry heat</p> Signup and view all the answers

    What is the main limitation of the red heat sterilization method?

    <p>It is ineffective for articles that cannot withstand high temperatures.</p> Signup and view all the answers

    Which sterilization method is characterized by the complete destruction of contaminated materials?

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

    What is a significant risk associated with the flaming method of sterilization?

    <p>It can crack glassware.</p> Signup and view all the answers

    Which statement about the hot air oven is NOT accurate?

    <p>It sterilizes articles through direct contact with the air.</p> Signup and view all the answers

    Which materials should NOT be incinerated due to potential hazardous emissions?

    <p>Polystyrene materials</p> Signup and view all the answers

    What is essential to ensure the effective operation of a hot air oven?

    <p>Inclusion of a thermostat control and temperature indicator.</p> Signup and view all the answers

    What temperature and duration are typically used in the hot air oven sterilization method?

    <p>160°C for 1 hour</p> Signup and view all the answers

    What type of biological indicator is commonly used for validating hot air oven sterilization?

    <p>106 spores of Bacillus subtilis var niger</p> Signup and view all the answers

    What is the main purpose of inspissation?

    <p>To solidify and disinfect egg and serum containing media</p> Signup and view all the answers

    Why is boiling not considered a proper method of sterilization?

    <p>It cannot kill all bacterial spores</p> Signup and view all the answers

    What is the purpose of adding sodium bicarbonate during boiling?

    <p>To enhance the killing activity against bacterial spores</p> Signup and view all the answers

    What is Tyndallisation primarily used for?

    <p>To periodically kill bacteria over multiple days</p> Signup and view all the answers

    What is the main advantage of using an autoclave for sterilization?

    <p>It rapidly kills microorganisms using pressurized steam</p> Signup and view all the answers

    During autoclaving, why is it important to flush air out of the chamber?

    <p>To ensure efficient heat transfer</p> Signup and view all the answers

    Which of the following statements about the process of boiling is true?

    <p>It can kill most vegetative bacteria and viruses almost immediately</p> Signup and view all the answers

    What is an essential feature of the steamers used in sterilization?

    <p>They must have a closed lid during operation</p> Signup and view all the answers

    What happens if the drain screen in the autoclave is blocked?

    <p>Air may entrap, hindering sterilization.</p> Signup and view all the answers

    At what temperature is sterilization achieved using an autoclave at a pressure of 15 lbs?

    <p>121o C</p> Signup and view all the answers

    Which of the following is NOT an advantage of using steam for sterilization?

    <p>Requires less time than dry heat sterilization.</p> Signup and view all the answers

    What is the recommendation for sterilizing materials associated with spongiform encephalopathies?

    <p>135o C for at least one hour.</p> Signup and view all the answers

    Which component is NOT typically found in a simple autoclave?

    <p>A vacuum pump for creating negative pressure.</p> Signup and view all the answers

    Why should articles in the autoclave not be tightly packed?

    <p>To ensure proper contact with steam.</p> Signup and view all the answers

    What is the correct procedure for starting the autoclave?

    <p>Heat the water with the discharge tap open.</p> Signup and view all the answers

    What occurs when the autoclave is allowed to cool after sterilization?

    <p>Pressure equalizes with atmospheric pressure.</p> Signup and view all the answers

    What classification applies to devices that contact sterile tissue or the bloodstream?

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

    Which level of disinfection allows for a small number of bacterial endospores to remain?

    <p>High level disinfection</p> Signup and view all the answers

    What type of devices must undergo High Level Disinfection (HLD) before use?

    <p>Semi-critical devices</p> Signup and view all the answers

    Which classification of devices poses a low risk of infection transmission?

    <p>Non-critical</p> Signup and view all the answers

    What is the primary purpose of sterilization in medical devices?

    <p>To destroy all microorganisms</p> Signup and view all the answers

    Which statement is true about critical ultrasound probes?

    <p>They must always be sterilized when used.</p> Signup and view all the answers

    What is the appropriate disinfection level for devices that contact mucous membranes or non-intact skin?

    <p>High level disinfection</p> Signup and view all the answers

    Which type of disinfection should be applied to devices that only contact intact skin?

    <p>Intermediate level disinfection</p> Signup and view all the answers

    Study Notes

    Sterilization and Disinfection

    • Sterilization is the process of killing all living microorganisms, including bacterial spores. It can be achieved by physical, chemical, or physiochemical means. Chemicals used for sterilization are called chemisterilants.
    • Sterilization procedures include methods like heat, ethylene oxide gas, hydrogen peroxide gas, plasma, ozone, and radiation.
    • Sterility Assurance Level (SAL) measures the probability of a microorganism surviving treatment. It's less than one in one million.
    • Disinfection is the process of eliminating most pathogenic microorganisms (excluding bacterial spores) from inanimate objects. It can be achieved by physical or chemical methods. Chemicals used in disinfection are called disinfectants.
    • Different disinfectants have varying effectiveness against different microorganisms. Not all disinfectants kill all microorganisms. Some methods, like filtration, separate microorganisms but do not kill them. Disinfection is not synonymous with sterilization.
    • Decontamination is the process of removing contaminating pathogenic microorganisms from items. This is accomplished through sterilization or disinfection. This process uses physical or chemical means to remove, inactivate, or destroy living organisms so they are no longer infectious.
    • Sanitization is a process of chemical or mechanical cleaning, used by the food industry to reduce microbes on eating utensils to safe levels for public health.
    • Asepsis is the use of techniques like gloves, air filters, UV rays to achieve a microbe-free environment.
    • Antisepsis is the use of chemicals (antiseptics) to make skin or mucous membranes free of pathogenic microorganisms.
    • Bacteriostasis is the inhibition of bacterial growth without killing the bacteria.
    • Bactericidal is a chemical that kills bacteria. Bactericidal chemicals have various names based on their target organisms, like virucidal, fungicidal, etc.
    • Antibiotics are substances produced by one microbe that inhibit the growth or kill other microbes. Often the term includes synthetic and semi-synthetic antimicrobial agents.

    Methods of Sterilization

    • Physical Methods:
      • Sunlight: The microbicidal activity is due to ultraviolet rays that kill bacteria. It provides a natural method of disinfection for water bodies.
      • Heat: It's the most reliable sterilization method for heat-resistant articles.
    • Moist heat is more effective than dry heat. Temperature and time for sterilization are inversely proportional.
    • Factors affecting sterilization include the nature of heat, temperature and time, number of microorganisms, nature of microorganism, type of material, and presence of organic material.
    • Different types of dry heat methods include red heat, flaming, incineration, and hot air ovens. Dry heat methods are limited to items that can take high temperatures.
    • Moist heat is also used in various ways, like autoclaves or boiling. Articles that can tolerate high temperatures can be sterilized at lower temperatures by increasing the duration of exposure.
    • Infrared Rays: Sterilization is achieved by high temperatures in a tunnel with infrared radiators. Articles to be sterilized are placed on conveyors. This method is well-suited for certain heat resistant articles.
    • Moist Heat (Pasteurization): A common method in food and dairy industries. Techniques like the holder method (63°C for 30 minutes) and the flash method (72°C for 15 seconds) are used.

    More Sterilization Methods

    • Steam Sterilization (Autoclaving): Uses saturated steam under pressure to kill microorganisms and spores. Recommended for heat-sensitive instruments and other medical materials. Different types of autoclaves are also described (simple pressure cooker, steam jacketed, high pressure).
    • Radiation:
      • Ionizing radiation (gamma rays, electron beams) are used to sterilize items. They are very effective and can penetrate deeply yet have disadvantages like long exposure times and special equipment requirements.
      • Non-ionizing radiation (UV rays) has limited penetration and is best suited for surface disinfection rather than sterilization.

    Chemical Methods for Disinfection

    • Disinfectants are chemical agents that kill pathogenic bacteria from inanimate surfaces. Some examples are:
      • Alcohols (dehydrate cells and cause protein coagulation)
      • Aldehydes (alkylate amino-, carboxyl-, or hydroxyl groups, effective on most microbes including spores)
      • Phenol & Phenolic Compounds (disrupt cell membranes and inactivate enzymes).
      • Halogens (oxidizing agents causing damage by oxidation of essential sulfur compounds in enzymes).
      • Heavy Metals (precipitate proteins and oxidize sulfydryl groups.)
      • Surface-Active Agents (concentrate at interfaces; widely used as disinfectants and antiseptics)
    • Hydrogen Peroxide: An oxidizing agent that produces hydroxyl free radicals (damaging proteins and DNA). Can be used for sterilization of instruments and equipment, as well as for wound deodorization.
    • Ethylene Oxide (EO) method: This is an alkylating agent typically used with a humidity-rich environment and may be used to sterilize several sensitive and heat-labile items including fabrics, plastics, rubber, and complex equipment. It's effective against spores.
    • Beta-Propiolactone: An alkylating agent, often used for sterilizing biological and pharmaceutical products, is efficient and effective but can be toxic for living organisms.

    Spaulding Classification

    • Critical devices require sterilization to eliminate all microorganisms (e.g., surgical instruments that come into contact with sterile tissues or the bloodstream).
    • Semi-critical devices require high-level disinfection (kills all vegetative microbes, inactivates most viruses and some bacterial spores) to prevent the spreading of microbes (e.g., endoscopes, respiratory devices).
    • Non-critical devices require low-level disinfection (kills most vegetative microbes, some fungi, and inactivates some viruses) to reduce microbes on surfaces (e.g., furniture and tabletops).

    Testing Disinfectants

    • Disinfectants need to be tested to measure their effective concentration, necessary time and to monitor their activity. Several methods exist like Koch's method, Rideal Walker method, Chick Martin method, and Capacity use dilution tests. Each of them has advantages and disadvantages. Often, particular tests tend to be best for specific types of disinfectants.

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    Sterilization and Disinfection PDF

    Description

    Test your knowledge on sterilization and disinfection processes. This quiz covers methods, chemical agents, and the differences between sterilization and disinfection. Challenge yourself to see how well you understand these crucial concepts in microbiology.

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