Sterilization and Disinfection Techniques

Podcast

Play an AI-generated podcast conversation about this lesson

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?

Coagulating proteins Signup and view all the answers

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

Non-Ionizing radiation Signup and view all the answers

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

Coagulating their proteins Signup and view all the answers

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

63°C for 30 minutes Signup and view all the answers

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

It is not effective against endospores. Signup and view all the answers

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

To measure the pressure inside the chamber Signup and view all the answers

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

56°C for 1 hour Signup and view all the answers

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

Oxidation effects Signup and view all the answers

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

50°C to 250/300°C Signup and view all the answers

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

To control the temperature Signup and view all the answers

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

Incineration Signup and view all the answers

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

121º for 15 minutes Signup and view all the answers

What type of filtration is classified under mechanical removal methods?

Air and liquid filtration Signup and view all the answers

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

Filtration Signup and view all the answers

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

Creating a biofilm Signup and view all the answers

What is the recommended concentration of ethanol for disinfection purposes?

60-90% in water Signup and view all the answers

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

160°C for 2 hours Signup and view all the answers

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

Dry heat sterilization Signup and view all the answers

Which chemical is known for both bactericidal and sporicidal effects?

Glutaraldehyde Signup and view all the answers

What is one of the main uses of formaldehyde?

Preserving anatomical specimens Signup and view all the answers

How does hydrogen peroxide function as an antiseptic?

By cleaning wounds through oxidation Signup and view all the answers

Which of the following statements about halogens is true?

Halogens are commonly used in skin disinfectants Signup and view all the answers

Why might hydrogen peroxide be less effective against certain organisms?

Because some organisms produce catalase Signup and view all the answers

What is the primary aim of sterilization?

To destroy all viable microorganisms Signup and view all the answers

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

Bacteriostatic agent Signup and view all the answers

What does antisepsis involve?

Using less toxic materials on skin surfaces Signup and view all the answers

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

Degermation Signup and view all the answers

What is the definition of sanitization?

Cleansing technique that removes microbes mechanically Signup and view all the answers

What does the term 'asepsis' refer to?

Absence of significant contamination Signup and view all the answers

Which statement accurately describes disinfection?

It removes vegetative microbes but not endospores. Signup and view all the answers

What is the role of a sporicidal agent?

To kill bacterial spores Signup and view all the answers

What is the primary purpose of sterilization?

Removing all microorganisms including spores Signup and view all the answers

Which method is commonly used for sterilization?

Ethylene oxide gas exposure Signup and view all the answers

What differentiates disinfection from sterilization?

Disinfection does not eliminate all microorganisms. Signup and view all the answers

What historical advance in medicine helped to reduce surgical infections?

Use of antiseptic techniques Signup and view all the answers

What is primarily targeted by sterilization procedures?

All living microorganisms Signup and view all the answers

Which of the following methods can be used for disinfection?

Ultraviolet light Signup and view all the answers

Which factor is NOT a method of microbial growth control?

Enhancement of nutrient availability Signup and view all the answers

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

High risk of nosocomial infections Signup and view all the answers

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.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

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.