Sterilization Methods PDF

# MICROBIAL CONTROL ## Sterilisation, Disinfection, and Antisepsis Dr. Abdulrahman Alsultan 7/11/2024 ## Learning Objectives - The purpose of sterilization, disinfection and antisepsis. - The principles of sterilization, disinfection and antisepsis. - The most important methods for sterilization,...

# MICROBIAL CONTROL ## Sterilisation, Disinfection, and Antisepsis Dr. Abdulrahman Alsultan 7/11/2024 ## Learning Objectives - The purpose of sterilization, disinfection and antisepsis. - The principles of sterilization, disinfection and antisepsis. - The most important methods for sterilization, disinfection and antisepsis. ## What is the main purpose of sterilization, disinfection and antisepsis? **Control of infections** ## Sterilization - Sterilisation is the process that eliminates or kills all forms of microbial life. - It is the total destruction of all microbes including the more resilient forms such as spores. - This can be achieved using gas vapour, physical or chemical sterilant. **The purpose**: To achieve the Safe Preservation at Room Temperature of treated products. ## Methods of sterilization ### Physical Sterilants: - Flaming, steam under pressure, - filtration, ultraviolet radiation and - ionizing radiation ### Chemical sterilants: - per acetic acid - glutaraldehyde ### Gas Vapour sterilants: - ethylene oxide, - formaldehyde, - hydrogen peroxide vapour, - plasma gas - Requires prolonged exposure times and damages many instruments. - Not Currently recommended. ## Other types of heating methods - Boiling is inefficient because only at maximum temperature of 100°C - Vegetative organisms are killed but not the spores which remain Viable. - Widely used, inexpensive, non-toxic, Reliable method of sterilization. ## Chemical methods of sterilization ### Gas Vapour sterilants: - Ethylene oxide, - Formaldehyde, - Hydrogen peroxide vapour, - Plasma gas **Ethylene oxide gas** - Used to sterilize sensitive items such as catheters and multi-lumen tubing products. - Plastic packaging or plastic containers. - Equipment with integrated-electronics - Wound care dressings **Gas Vapor sterilants:** - Plasma gas sterilization - Effective in destroying the components of microorganisms, such as enzymes, nucleic acids, and DNA. **Advantages**: Efficient sterilizing method. None toxic bye products. ## Chemical sterilization - In an automated machine - To sterilize medical, surgical, and dental instruments (e.g., endoscopes, bronchoscopes). ## Chemical sterilization 2 - Aldehydes (glutaraldehyde) It is used to sterilize surgical instruments. ## Disinfection - Disinfectants: are substances that are applied to non-living objects to destroy microorganisms that are living on the objects. - Disinfection does not necessarily kill all microorganisms, especially resistant bacterial pores - It is less effective than sterilisation which is an extreme physical and/or chemical process that kills all types of life **What is the Purpose of disinfection?** - To make a surface free of any disease-causing microorganisms that are normally of health-hazard. - Microbes are destroyed by disinfection but the more resilient organisms can survive. ## Disinfectant levels They can be grouped into three: - **high level**, used on equipment that can not withstand sterilisation; e.g. Surgical equipment with plastic - **intermediate level** disinfectants (alcohols) used to clean surfaces or instruments on which contamination with spores are unlikely. - **low level** disinfectants (quaternary ammonium compounds), used to treat non critical devices such as blood pressure kits, stethoscopes ## Methods of Disinfection - Heat; moist heat 750C to 1000C - Liquid: hydrogen peroxide, Formaldehyde, alcohol, chlorine dioxide ## High-level disinfectants - Used for items that cannot withstand sterilization procedures (e.g. certain types of endoscopes and surgical instruments with plastic components). - Examples: - moist heat - and use of chemicals such as glutaraldehyde, hydrogen peroxide, Peracetic acid and chlorine compounds. ## Chlorine compounds: - Chlorine is a very strong oxidizing agent - Aqueous solutions of chlorine are rapid bactericidal. - However, spore-forming organisms are more resistant. ## Intermediate-level disinfectants - Used to clean surfaces or instruments where contamination with bacterial spores and other resistant organisms is unlikely. - It is used for semi-critical instruments. - e.g. flexible fibre optic endoscopes, laryngoscopes, vaginal specula, anaesthesia breathing circuits, and other items. - Examples: alcohols, iodophor compounds, phenolic compounds ## Alcohols - Most commonly used are: ethanol and isopropanol. - They are rapidly bactericidal against vegetative bacteria, mycobacteria, some fungi, and lipid-containing viruses. - Do NOT act against bacterial spores and - Have poor activity against some fungi and Non-lipid-containing viruses. - Uses: for skin surfaces and, to disinfect items such as thermometers ## Iodine (tincture of iodine) - Is a highly reactive element that precipitates proteins and oxidizes essential enzymes. - It is microbicidal against virtually all organisms, including spore-forming bacteria and mycobacteria. ## Iodophor compounds - (iodo “iodine”; phor, “carrier”): Povidone iodine (iodine complexed with polyvinylpyrrolidone) ## Phenolic compounds e.g. phenol carbolic acid - Phenolic compounds are active against the Mycobacteria because the cell wall of these organisms has a very high concentration of lipids. ## Low-level disinfectants - Used to treat non-critical instruments and devices, such as blood pressure cuffs, electro cardiogram electrodes, and stethoscopes. - Examples: quaternary ammonium compounds - Are bacteriostatic at low concentrations and bactericidal at high concentrations. However, organisms such as *Pseudomonas, Mycobacterium,* many viruses, bacterial spores and the fungus *Trichophyton* are resistant to these compounds. ## Antiseptics - They are antimicrobial substances that are applied to; living tissue to reduce possibility of infection or sepsis. - They’re used to reduce the number of microbes on skin surfaces. - No sporicidal action is implied. ## Antiseptic agents - They are selected for their safety and efficacy. - Examples: Alcohol, 70% - 90% [e.g. lodophor (Betadine) ChlorhexidineTriclosan ## Alcohol - Advantages include the following: Excellent activity against almost all groups of organisms except spores. they are Non-toxic. - Disadvantages: Dryness to skin surface [remove lipids] Have no residual activity Inactivated by organic matter (clean the skin before alcohol is applied. ## Iodophors (Betadine) - Advantages: - relatively stable - Non toxic to tissues - Activity is similar to that of alcohols. - Disadvantages: - Slightly more toxic to the skin than alcohol compared with other iodine solutions ## Chlorhexidine - Has broad antimicrobial activity. - Has residual activity - Kills organisms at a much slower rate than alcohol. ## Triclosan: - active against bacteria but not against many other organisms. - It is a common antiseptic agent in deodorant soaps and some toothpaste products. ## Thank you