Sterilization and Disinfection Techniques
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Questions and Answers

What is the primary action by which Hydrogen peroxide inhibits enzymatic activity?

  • Binding to active sites of enzymes
  • Altering membrane permeability
  • Attacking sulfhydryl groups (correct)
  • Disrupting DNA synthesis

Which gas is known for its sweet ethereal smell and effectiveness against various microorganisms including spores?

  • Carbon Dioxide
  • Chlorine Gas
  • Ethylene Oxide (correct)
  • Nitrogen Dioxide

Which of the following materials is used in the filtration process to remove bacteria from heat labile liquids?

  • Glass wool
  • Paper filters
  • Activated charcoal
  • Candle filters (correct)

What property of Metallic salts contributes to their function as disinfectants?

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

What type of radiation is considered as 'hot air sterilization' and is commonly used for prepacked syringes?

<p>Non-Ionizing radiation (A)</p> Signup and view all the answers

What is the primary mechanism by which moist heat sterilization kills microorganisms?

<p>Coagulating their proteins (A)</p> Signup and view all the answers

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

<p>63°C for 30 minutes (D)</p> Signup and view all the answers

Which statement accurately describes the effectiveness of boiling as a method of sterilization?

<p>It is not effective against endospores. (D)</p> Signup and view all the answers

What is the purpose of the pressure gauge in an autoclave?

<p>To measure the pressure inside the chamber (D)</p> Signup and view all the answers

What temperature is typically used in a special vaccine bath to inactivate non-sporing bacteria?

<p>56°C for 1 hour (A)</p> Signup and view all the answers

What is the primary method of sterilization employed by a dry heat oven?

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

Which temperature range is typically used for sterilization in a dry heat oven?

<p>50°C to 250/300°C (A)</p> Signup and view all the answers

What is the purpose of a thermostat in a dry heat sterilization process?

<p>To control the temperature (B)</p> Signup and view all the answers

Which method is specifically noted for destroying contaminated materials such as cloth and carcasses?

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

What temperature and duration are typically required for effective sterilization using pressurized steam?

<p>121º for 15 minutes (B)</p> Signup and view all the answers

What type of filtration is classified under mechanical removal methods?

<p>Air and liquid filtration (A)</p> Signup and view all the answers

Which of the following is NOT a chemical agent used in microbial control?

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

Which of the following is NOT a method by which chemical agents can act?

<p>Creating a biofilm (D)</p> Signup and view all the answers

What is the recommended concentration of ethanol for disinfection purposes?

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

At what temperature and duration should articles ideally be held in a dry heat oven for sterilization?

<p>160°C for 2 hours (C)</p> Signup and view all the answers

Which method is utilized for sterilizing instruments like forceps and scalpels?

<p>Dry heat sterilization (A)</p> Signup and view all the answers

Which chemical is known for both bactericidal and sporicidal effects?

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

What is one of the main uses of formaldehyde?

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

How does hydrogen peroxide function as an antiseptic?

<p>By cleaning wounds through oxidation (D)</p> Signup and view all the answers

Which of the following statements about halogens is true?

<p>Halogens are commonly used in skin disinfectants (D)</p> Signup and view all the answers

Why might hydrogen peroxide be less effective against certain organisms?

<p>Because some organisms produce catalase (C)</p> Signup and view all the answers

What is the primary aim of sterilization?

<p>To destroy all viable microorganisms (C)</p> Signup and view all the answers

Which agent is specifically used to inhibit bacterial growth without killing them?

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

What does antisepsis involve?

<p>Using less toxic materials on skin surfaces (C)</p> Signup and view all the answers

Which of the following processes would require a mechanical removal of microbes?

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

What is the definition of sanitization?

<p>Cleansing technique that removes microbes mechanically (A)</p> Signup and view all the answers

What does the term 'asepsis' refer to?

<p>Absence of significant contamination (C)</p> Signup and view all the answers

Which statement accurately describes disinfection?

<p>It removes vegetative microbes but not endospores. (C)</p> Signup and view all the answers

What is the role of a sporicidal agent?

<p>To kill bacterial spores (B)</p> Signup and view all the answers

What is the primary purpose of sterilization?

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

Which method is commonly used for sterilization?

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

What differentiates disinfection from sterilization?

<p>Disinfection does not eliminate all microorganisms. (B)</p> Signup and view all the answers

What historical advance in medicine helped to reduce surgical infections?

<p>Use of antiseptic techniques (B)</p> Signup and view all the answers

What is primarily targeted by sterilization procedures?

<p>All living microorganisms (D)</p> Signup and view all the answers

Which of the following methods can be used for disinfection?

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

Which factor is NOT a method of microbial growth control?

<p>Enhancement of nutrient availability (B)</p> Signup and view all the answers

What was a significant risk associated with surgical procedures before aseptic techniques?

<p>High risk of nosocomial infections (B)</p> Signup and view all the answers

Flashcards

What is sterilization?

The complete removal or destruction of all microorganisms, including highly resistant bacterial spores.

What is disinfection?

A process that eliminates most, but not all, microorganisms. It targets harmful pathogens but may leave some organisms and spores alive.

What are aseptic techniques?

A method used to prevent microbial contamination during surgical procedures.

Describe autoclaving.

A method of sterilization involving exposure to high-pressure steam at a specific temperature for a set time.

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Describe ethylene oxide gas sterilization.

A method of sterilization where objects are exposed to ethylene oxide gas.

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Describe filtration sterilization.

A sterilization method in which microorganisms are removed through a filter.

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What are nosocomial infections?

Infections acquired in a healthcare setting.

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What is the role of sterilization and disinfection in disease control?

The prevention of infection and disease.

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Antiseptics

Chemicals used to kill microorganisms on the surface of skin and mucous membranes.

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Sterilization

A process that destroys all viable microbes, including viruses and endospores.

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Disinfection

A process to destroy vegetative pathogens, but not endospores. This process is used on inanimate objects.

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Sanitization

Any cleansing technique that mechanically removes microbes.

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Microbicidal

Means to kill.

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Microbiostatic

Means inhibition of growth and multiplication.

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Bactericide

An agent that kills bacteria.

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Bacteriostatic

An agent that inhibits the growth of bacteria.

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Sterilization by Dry Heat

A method of sterilization that uses high temperatures to kill microbes by oxidation. This method is commonly used for instruments, powders, and oils. The process involves heating items in a dry oven at temperatures ranging from 160°C to 250°C or 300°C for a specific duration, typically 2 hours.

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Flaming/Incineration

A method of sterilization using a Bunsen burner flame. This process is quick and effective for sterilizing instruments like inoculation loops, forceps, and spatulas by heating them to a red-hot temperature. It's also ideal for incinerating contaminated materials such as cloths, animal carcasses, and medical waste.

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Moist Heat Sterilization

The use of heat in a controlled environment to kill microbes. This method includes boiling water, hot water, and steam under pressure (autoclaving).

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Filtration

A method of physically removing microbes from a substance, such as air or liquids, by passing it through a filter with pores small enough to trap microbes. This method is commonly used for sterilizing solutions, air in hospitals, and laboratory environments.

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Ionizing Radiation

A type of radiation that uses high-energy rays to penetrate and damage the DNA of microbes, leading to their inactivation. This method is effective for sterilizing medical equipment, pharmaceuticals, and other materials. Different types of ionizing radiation include X-rays, cathode rays, and gamma rays.

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Pasteurization

A process used to kill harmful bacteria in milk without making it sterile. It involves either heating milk at 63°C for 30 minutes (Holder method) or rapidly heating it to 72°C for 15-20 seconds followed by quick cooling (Flash process).

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Autoclave

A device that uses steam under pressure to sterilize materials. It consists of a chamber with a lid, a pressure gauge, and a safety valve. The steam pressure raises the temperature inside the chamber, killing bacteria.

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Boiling (100°C)

To kill the vegetative forms of bacteria. This does not kill endospores and may not be effective against certain viruses, like Hepatitis virus which can survive up to 30 minutes.

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Hot Water Bath

A method used to inactivate non-sporing bacteria in vaccines. It involves heating vaccines in a water bath at 60°C for one hour.

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Hydrogen Peroxide

A chemical that causes oxidation, damaging sulfhydryl groups in proteins, preventing enzymatic activity.

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Ethylene Oxide

A colorless, penetrating gas with a sweet smell, highly effective against various microbes, including viruses and spores.

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Metallic Salts (Silver, Copper, Mercury)

Salts of silver, copper, and mercury that act as disinfectants by coagulating proteins. They have bacteriostatic, weak bactericidal, and limited fungicidal action.

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Sterilization by Filtration

A process of removing bacteria by passing a liquid through a filter. It's used for heat-sensitive solutions like sera and antibiotics.

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Non-Ionizing Radiation

Radiation that does not have enough energy to ionize atoms, like UV rays. It is used for rapid, safe heat sterilization of pre-packaged medical items.

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How Chemical Disinfection Works

Chemical agents disrupt the structure and function of microorganisms through various mechanisms.

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Factors Affecting Disinfection

The effectiveness of a disinfectant depends on its concentration, the presence of organic matter, pH, and exposure time.

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Alcohols as Disinfectants

Ethanol and isopropyl alcohol are commonly used disinfectants, effective against most bacteria, but not spores.

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Aldehydes as Disinfectants

Formaldehyde and glutaraldehyde are powerful disinfectants that can kill bacteria, spores, fungi, and viruses.

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Halogens as Disinfectants

Iodine is a widely used skin disinfectant, effective against bacteria and some spores, while chlorine is used for water disinfection.

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Phenols as Disinfectants

Phenols, like Lysol, are powerful disinfectants derived from coal tar.

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Hydrogen Peroxide as Disinfectant

Hydrogen peroxide is used as an antiseptic for wounds and contact lenses, but its effectiveness is limited by bacterial catalase.

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Study Notes

Sterilization, Disinfection, and Antisepsis

  • Students should be able to define sterilization, disinfection, and antisepsis.
  • Understand methods of sterilization and disinfection: physical methods, chemical methods, and mechanical removal methods.
  • Explain the role of sterilization and disinfection in disease control.

Introduction

  • Microorganisms are agents of contamination, infection, and decay.
  • Removing microorganisms is necessary to prevent food spoilage and contamination.
  • Early civilizations employed methods like salting, smoking, pickling, and sunlight exposure to preserve food.

Aseptic Techniques

  • In the mid-1800s, Lister developed aseptic techniques to prevent surgical wound contamination.
  • Prior to this, nosocomial infections caused deaths in 10% of surgeries and up to 25% of mothers delivering in hospitals died from infection.

Methods of Microbial Growth Control

  • Alteration of membrane permeability.
  • Damage to proteins.
  • Damage to nucleic acids.
  • Prions are the most resistant, followed by bacterial spores.
  • Mycobacteria, cysts of protozoa, vegetative protozoa, and gram-negative bacteria are also resistant.
  • Gram-positive bacteria and viruses without lipid envelopes have intermediate resistance.
  • The least resistant are viruses with lipid envelopes.

Definition of Sterilization

  • Sterilization is the process of completely eliminating all microorganisms, including spores.
  • It's vital for surgical procedures and other processes needing a sterile environment.

Methods of Sterilization

  • Physical methods include steam under pressure (autoclaving), filtration, ultraviolet radiation, ionizing radiation, and dry heat.
  • Gas vapor methods include ethylene oxide, hydrogen peroxide vapor, and plasma gas.
  • Chemical methods include peracetic acid, glutaraldehyde, and others.

Disinfection

  • Disinfection kills many microorganisms but not all, critically important in keeping a clean hygienic environment, including bacterial spores.
  • Disinfectants include corrosive phenolic compounds, ethanol, and iodine.
  • Antisepsis involves chemicals used on skin/mucous membranes, less corrosive than disinfectants; it's vital for preventing contamination.

Methods of Disinfection

  • Moist heat sterilization involves using temperatures between 75°C and 100°C for 30 minutes.
  • Liquids use various chemical disinfectants (e.g., glutaraldehyde, hydrogen peroxide, chlorine compounds, phenolics, lodophors).
  • Quaternary ammonium compounds are used in intermediate concentrations.

Terminology

  • Sterilization: A process destroying all microorganisms (including viruses and spores).
  • Disinfection: A process that destroys vegetative pathogens, not spores; applicable to inanimate objects.
  • Antiseptic: Disinfectants applied directly to exposed body surfaces.
  • Sanitization: Any cleansing technique that mechanically removes microbes.
  • Degermation: Mechanical removal of microbes from a surface.
  • Sepsis: Bacterial contamination.
  • Asepsis: Absence of significant contamination.
  • Bactericidal: Kills bacteria.
  • Bacteriostatic: Inhibits bacterial growth without killing them.
  • Sporicidal: Kills spores.

Antiseptic Agents

  • List of various antiseptic agents and concentrations

Mechanical Removal Methods

  • Filtration methods are used for sterilizing liquids (e.g., sera, antibiotics) and gases.

Sterilization by Dry Heat

  • Kills microorganisms through oxidation.
  • Dry heat methods include incineration to sterilize items such as inoculation loops, forceps, and spatulas.
  • Dry oven, used for sterilizing items such as instruments, that can withstand high temperatures.

Sterilization by Moist Heat

  • Kills microorganisms by coagulating their proteins. Methods include boiling, steaming at atmospheric pressure, and autoclaving.

Pasteurization

  • A process that kills pathogens in milk without sterilizing it.
  • Methods include Holder method (63°C for 30mins) and Rapid Flash method (72°C for 15-20 seconds, cooling to 13°C).

Hot Water Bath

  • Used to inactivate bacteria for vaccine preparation.
  • Materials are heated in hot water at 60°C for one hour

Temperature at 100°C (Boiling)

  • Boiling kills vegetative forms of bacterial pathogens but endospores may potentially survive 20 hours.

Steam under Pressure (Autoclave)

  • Works on the principle of steam under pressure; invented by Chamberland (1879).
  • Autoclave consists of a vertical/horizontal cylinder, a perforated shelf, and other components for steam sterilization

Radiation

  • Non-ionizing radiation: Long wavelengths, absorbed as heat, used in rapid mass sterilization of pre-packaged syringes and catheters (e.g., UV rays).
  • Ionizing radiation: High penetrative power, cold sterilization (e.g., X-rays, gamma rays, and cosmic rays), used for sterilizing plastics, syringes, catheters, fabrics, and grease foils.

Ultrasonic and Sonic Vibration

  • Bactericidal but microorganisms vary in their sensitivity, not widely used in sterilization and disinfection.

Physical and Chemical Sterilants Table

  • A detailed table of physical and chemical sterilants including their respective concentration/level and use

Germicidal Properties of Disinfectants and Antiseptic Agents Table

  • Table displaying the effectiveness of various chemical and antiseptic agents against different types of microorganisms (bacteria, mycobacteria, bacterial spores, fungi, and viruses).

References

  • List of various references on microbiology, medical microbiology, review books etc.

Thank You

  • Acknowledgement for any questions.

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Sterilization, Disinfection, and Antisepsis PDF

Description

This quiz covers key concepts of sterilization, disinfection, and antisepsis, including various methods and their roles in disease control. Students will learn about historical techniques and modern practices essential for maintaining aseptic conditions. Test your knowledge on the importance of microbial growth control in healthcare and food safety.

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