Podcast
Questions and Answers
What is the primary goal of sterilization?
What is the primary goal of sterilization?
Which method is commonly used for sterilization that involves heat?
Which method is commonly used for sterilization that involves heat?
What differentiates disinfection from sterilization?
What differentiates disinfection from sterilization?
What is a significant historical impact of Lister's development of aseptic techniques?
What is a significant historical impact of Lister's development of aseptic techniques?
Signup and view all the answers
Which chemical is commonly used for disinfection on skin and mucous membranes?
Which chemical is commonly used for disinfection on skin and mucous membranes?
Signup and view all the answers
What is the exposure time and temperature required for sterilization using an autoclave?
What is the exposure time and temperature required for sterilization using an autoclave?
Signup and view all the answers
Which of the following methods uses intermittent sterilization?
Which of the following methods uses intermittent sterilization?
Signup and view all the answers
What is a key characteristic of non-ionising radiation during sterilization?
What is a key characteristic of non-ionising radiation during sterilization?
Signup and view all the answers
What device was invented by Charles Chamberland for sterilization purposes?
What device was invented by Charles Chamberland for sterilization purposes?
Signup and view all the answers
What type of sterilization method is best suited for rapid mass sterilization of prepacked syringes?
What type of sterilization method is best suited for rapid mass sterilization of prepacked syringes?
Signup and view all the answers
Which chemical agent is primarily effective against Tubercle bacilli, fungi, and viruses?
Which chemical agent is primarily effective against Tubercle bacilli, fungi, and viruses?
Signup and view all the answers
What is a key characteristic of alcohols as disinfectants?
What is a key characteristic of alcohols as disinfectants?
Signup and view all the answers
What principle is not mentioned as effective for achieving disinfection?
What principle is not mentioned as effective for achieving disinfection?
Signup and view all the answers
What is a notable limit of using ultrasonic and sonic vibration in sterilization?
What is a notable limit of using ultrasonic and sonic vibration in sterilization?
Signup and view all the answers
Which of the following acts through protein coagulation?
Which of the following acts through protein coagulation?
Signup and view all the answers
What is the primary purpose of incineration as discussed?
What is the primary purpose of incineration as discussed?
Signup and view all the answers
What is the function of moist heat sterilization?
What is the function of moist heat sterilization?
Signup and view all the answers
At what temperature does pasteurization of milk occur using the Holder method?
At what temperature does pasteurization of milk occur using the Holder method?
Signup and view all the answers
Which method is used to sterilize media such as Lowenstein-Jensen?
Which method is used to sterilize media such as Lowenstein-Jensen?
Signup and view all the answers
What is the maximum effectiveness of boiling in eliminating viruses?
What is the maximum effectiveness of boiling in eliminating viruses?
Signup and view all the answers
What characteristic does a steam sterilizer have?
What characteristic does a steam sterilizer have?
Signup and view all the answers
What temperature is used in a special vaccine bath to inactivate non-sporing bacteria?
What temperature is used in a special vaccine bath to inactivate non-sporing bacteria?
Signup and view all the answers
What is necessary for effective steam sterilization at atmospheric pressure?
What is necessary for effective steam sterilization at atmospheric pressure?
Signup and view all the answers
Which filter is specifically known for its high adsorbing tendency but is also carcinogenic?
Which filter is specifically known for its high adsorbing tendency but is also carcinogenic?
Signup and view all the answers
What is the main purpose of beta propiolactone (BPL) at a concentration of 0.2%?
What is the main purpose of beta propiolactone (BPL) at a concentration of 0.2%?
Signup and view all the answers
Which filter type works by fusing powdered glass particles and is known for its brittleness?
Which filter type works by fusing powdered glass particles and is known for its brittleness?
Signup and view all the answers
What type of filters are candle filters categorized into?
What type of filters are candle filters categorized into?
Signup and view all the answers
What are membrane filters primarily made of?
What are membrane filters primarily made of?
Signup and view all the answers
Which types of bacteria are aniline dyes effective against?
Which types of bacteria are aniline dyes effective against?
Signup and view all the answers
What is a key characteristic of acridine dyes?
What is a key characteristic of acridine dyes?
Signup and view all the answers
What is hydrogen peroxide's limitation as an antiseptic?
What is hydrogen peroxide's limitation as an antiseptic?
Signup and view all the answers
Which statement about phenols is true?
Which statement about phenols is true?
Signup and view all the answers
What is the primary use of ethylene oxide?
What is the primary use of ethylene oxide?
Signup and view all the answers
Which of the following is a known property of iodine solutions?
Which of the following is a known property of iodine solutions?
Signup and view all the answers
What is true regarding the use of phenols?
What is true regarding the use of phenols?
Signup and view all the answers
Hydrogen peroxide acts primarily as which type of agent?
Hydrogen peroxide acts primarily as which type of agent?
Signup and view all the answers
Study Notes
Sterilization, Disinfection & Antiseptic
- Microorganisms cause contamination, infection and decay
- Early civilizations used methods like salting, smoking, pickling and sunlight exposure to reduce microorganisms
- In the mid-1800s, Lister developed aseptic techniques to prevent contamination of surgical wounds
- Before this development, nosocomial infections caused death in 10% of surgeries and up to 25% of mothers delivering in hospitals died due to infection
- Methods of microbial growth control include alteration of membrane permeability, damage to proteins and damage to nucleic acids
- Different microorganisms have varying resistance to different methods
Definition of Sterilization
- Sterilization is the process of removing all microorganisms, including spores, from an item
- Sterilization is necessary before surgery
Methods of Sterilization
- Sterilization is usually done by autoclaving, which involves exposing materials to steam at 121°C under a pressure of 15 lb/in² for 15 minutes
- Surgical instruments that are damaged by heat can be sterilized by ethylene oxide gas
- Many intravenous solutions are sterilized by filtration
Definition of Disinfection
- Disinfection kills many, but not all, microorganisms
- Chemicals used to kill microorganisms on skin and mucous membranes are called antiseptics
Terminology
- Sterilization destroys all viable microbes, including viruses and endospores
- Disinfection destroys vegetative pathogens, not endospores (in inanimate objects)
- Antiseptics are disinfectants applied directly to exposed body surfaces
- Sanitization is a cleansing technique that mechanically removes microbes
- Degermation is the mechanical removal of microbes from a surface
- Aseptic refers to the absence of significant contamination
- A bactericidal agent kills bacteria, whilst a bacteriostatic agent inhibits their growth and multiplication
Bacteriostatic Agent and Bactericide
- A bacteriostatic agent inhibits bacterial growth but doesn't necessarily kill them
- A bactericide agent kills bacteria. Most do not kill endospores
Aim of Sterilization
- Asepsis is a practice that minimizes or eliminates contaminants like bacteria, viruses, fungi, and parasites in surgical or medical procedures to prevent infection
- Ideally, a sterile field is free of contaminants but difficult to achieve
- The goal of sterilization is to eliminate infection, not necessarily sterility
Methods of Sterilization
- Methods of sterilization include physical agents (e.g., heat, radiation) and chemical agents (e.g., gases, liquids) as well as mechanical methods of removal
Physical Agents
- Heat methods: incineration, dry oven, autoclaving (steam under pressure) , boiling water, pasteurization
- Radiation methods: ionizing (gamma rays, X-rays), non-ionizing radiation (UV)
Chemical Agents
- Gases: Ethylene oxide, Formaldehyde
- Liquids: Chemotherapy agents , Antiseptics
Mechanical Removal Methods
- Filtration (air, liquids)
Physical Methods of Sterilization (Examples)
- Hot Air Oven: Sterilizes items using oxidation, operated between 160°C and 250/300°C, with a holding period of 160°C for 1 hour for optimal results.
- Flaming: Used to sterilize inoculation loops and forceps through the use of a Bunsen burner
Incineration
- A method for destroying contaminated materials, animal carcasses, or pathological materials
Moist Heat Sterilization
- Kills microorganisms by coagulating their proteins.
Moist Heat Sterilization Methods
- Methods include: Temperature below 100° C (pasteurization, inspissator), 100° C (boiling), Steam at atmospheric pressure (Koch/Arnold's steamer), and Steam under pressure (autoclave).
Pasteurization
- Killing of pathogens in milk, not necessarily sterilizing it. Methods involve heating (Holder method) at 63°C for 30 minutes or (flash process) at 72°C for 15-20 seconds, followed by rapid cooling to 13°C
Water Bath
- Used to inactivate non-spore-forming bacteria.
- Sterilizing serum or body fluids with coagulable proteins.
Inspissator
- Sterilizes by heating to 80-85°C for half an hour for 3 consecutive days.
- Used to sterilize media, such as Lowenstein-Jensen and Loeffler's serum
Boiling
- Kills vegetative forms of bacterial pathogens (at 100°C).
- Some viruses can survive up to 30 minutes, and endospores can survive up to 20 hours.
Steam at Atmospheric Pressure
- Uses a steamer (e.g., Koch/Arnold), with a tin cabinet, conical lid for condensate drainage, and perforated tray to surround materials in steam
- Routine sterilization involves 90 minutes of exposure
Tyndallisation/Intermittent Sterilization
- Used for media containing sugar and gelatin
- 100°C exposure for 20 minutes for 3 successive days
Steam under Pressure (Autoclave)
- Invented by Charles Chamberland in 1879
- It works by utilizing steam under pressure.
- Essential parts include: exhaust valve, steam chamber, safety valve, pressure gauge, and operating valve
Radiation
- Two types are used (ionizing, non-ionizing)
Non-Ionizing Radiation
- Absorbed as heat
- Useful for rapid mass sterilization
- Examples include UV rays
Ionizing Radiation
- High penetrative power
- Does not cause an appreciable temperature increase
- Used for sterilizing plastics, syringes, catheters, fabrics, or metal foils
Ultrasonic and Sonic Vibration
- Microorganisms have varying sensitivity
Chemical Agents
- Act by protein coagulation, disrupting cell membranes, removing sulfhydryl groups, or substrate competition
Principles of Effective Disinfection
- Disinfectant concentration, organic matter removal, pH, and time
Alcohols
- Ethanol/Isopropyl alcohol; frequently used as disinfectants
- No action on spores
- Concentration is typically 60-90% in water
- Used for clinical thermometer disinfection and skin disinfection (venipuncture)
- 20 minutes application is enough for most viruses
Aldehydes
- Formaldehyde & Glutaraldehyde
- Formaldehyde is bactericidal, sporicidal, and lethal to viruses
- Glutaraldehyde is effective against mycobacteria, fungi, and viruses
Dyes
- Aniline dyes (e.g., Brilliant green, Malachite green, Crystal violet) are active against gram-positive bacteria
- Acridine dyes (e.g., Proflavine) are effective against gram-positive bacteria
Halogens
- Iodine (in aqueous and alcoholic solutions): widely used as a skin disinfectant
- Actively bactericidal with moderate spore activity
- Chlorine: used as a disinfectant in water
Phenols
- Obtained by coal tar distillation
- Powerful microbicidal agents
- Used in many hospital disinfectants (e.g., Lysol, cresol, Detol)
Uses
- Various combinations used in the control of pyogenic cocci in surgical neonatal units and aqueous solutions for wound treatment
Hydrogen Peroxide
- Used as an antiseptic to clean wounds and disinfect contact lenses
- Effectiveness limited by the organism's ability to produce catalase
- Oxidizing agent that attacks sulfhydryl groups, inhibiting enzymatic activity
Gases
- Ethylene Oxide: colorless, penetrating gas with a sweet, ethereal odor
- Effective against all microorganisms –viruses and spores
- Used in sterilizing heart-lung machines/ respirators and dental equipment.
Formaldehyde Gas
- Widely employed for the fumigation of operation theaters
Beta Propiolactone
- Used in fumigation.
- 0.2% BPL for sterilization and for rapid biocidal activity
- Very effective against viruses
Sterilization by Filtration
- Used to remove bacteria from heat-labile liquids such as sera and solutions of sugar, antibiotics
- Methods include: Candle filters (unglazed ceramic filter, diatomaceous earth filter), asbestos filter, sintered glass filter, membrane filters
References
- Principles and Methods of Sterilization in Health Sciences (2nd Edition).
- Jawetz Melnick & Adelbergs Medical Microbiology
- Review of Medical Microbiology and Immunology (Fourteenth Edition)
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on the techniques and principles behind sterilization and disinfection. This quiz covers various methods, historical impacts, and chemical agents used in these processes. Perfect for students studying microbiology or healthcare practices.
