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sterilization .pptx
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- 2. Contents 1. Defination 2. VariousAgents Used in Sterilization 3. Physical Agents 4. Chemical Agents 5. Indicators of sterilization 6. Ideal disinfectant should be
- 3. Sterilization Sterilization ismaking a substance free from all micro-organisms both in Vegetative and sporing states Spore is a reproductive structure that is adapted for extended periods of time in unfavourable conditions. Spore is a part of life cycles of many Bacteria, Plants, Algae, fungi, and some protozoa.
- 4. Terms used inSterilization Disinfection: The removal or destruction of all Pathogenic Organisms Capable of giving rise to infection. Disinfection does not Affect Spore state organism. Antisepsis: The term is indicated the prevention of infection usually by inhibiting the growth of bacteria in wounds or tissues. This is done by the Antiseptics Chemicals or disinfectants which can be safely applied on skin or mucous membrane to prevent infection by inhibiting the growth of bacteria. Ex-alcohols, quaternary ammonium compounds, chlorhexidine and other diguanides, antibacterial dyes, chlorine and hypochlorites, inorganic iodine compounds, metals, peroxides and permanganates, halogenated phenol derivatives and quinolone derivatives.
- 5. Bactericidal agents/ Germicides: Those which able to kill bacteria. Bacteriostatic agents: Only prevents multiplication of Bacteria, but they remain alive. Cleaning : Important Preparatory step before sterilization or Disinfection, by removing soil and other dirt. Decontamination: The process of rendering an article or area free of contaminants, including microbial, Chemical, radioactive, and other hazards
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- 7. Physical Agents: Sunlight Drying Heat Dry heat: flaming, incineration , Hot air Moist heat : Pasteurization, boiling, Steam under pressure. Filtration: Candles, Asbestos Pads, Membranes Radiation Ultrasonic and Sonic vibrations
- 8. Physical Methods ofSterilization Sunlight: 1. Action primarily due to UV rays however , effects vary from places to places. 2. Bacteria in Water are rapidly destroyed by sunlight. Limitation: in tropical countries the bactericidal effects of sunlight is more than that of seasoned countries.
- 9. Physical Methods ofSterilization Drying : Moisture is essential for growth of bacteria Drying in air has deleterious effect on many bacteria. Limitations: Spores are resistant to drying effects.
- 10. Physical Methods ofSterilization Heat Dry Heat Moist Heat Flaming: heating over fire, till they become red Hot . instruments like points of foreceps, spatuls, inoculation loops and wires. Incineration : it is a process that involves the combustion of organic substances contained in waste materials. Ex – contaminated cloths, pathological materials, PVC, polythene can be dealt.
- 11. Physical Methods ofSterilization Heat Dry Heat Moist Heat Hot Air Oven: • Hot Air Oven are electrical devices used in sterilization. • These oven uses dry heat to sterilize articles • Generally they can be operated from 50 to 300 degree celcius. • There is a thermostat controlling the tempreture. • This is the most widely used sterilization by dry heat. • Items: Glassware , foreceps, scalpels, all glass syringes, swabs, liquid paraffin etc (Materials should be properly arranged to allow free circulation of air.)
- 12. Physical Methods ofSterilization Heat Dry Heat Moist Heat Hot Air Oven: Advantages & Disadvantages: They donot require water and there is not much pressure build up within the oven, unlike autoclave , making them Safer to work with. Suitable to be used in laboratory environment. They are much smaller than autoclaves but can still be as effective. As they use dry heat instead of moist heat, some organism like prions , may not be killed by them every time.
- 13. Physical Methods ofSterilization Heat Dry Heat Moist Heat Moist Heat can be categorized into 3 groups 1. Tempreture below 100 C 2. Temperture at 100 C 3. Temperture above 100 C Pasteurisation of Milk • Holding period of 63 C for 30 min or 72 C for 15- 20 min followed by colling quickly to 13 C or lower • Target : all non sporing pathogens Eg. mycobacteria , brucellae etc. Limitaions: relatively heat resistant bacteria may survive the holder method.
- 14. Physical Methods ofSterilization Heat Dry Heat Moist Heat Tempreture at 100 C : Boiling Not recommended for sterilizing but used for disinfection. Sterilisation may be promoted by addition of 2 % sodium bicarbonate to the water.
- 15. Physical Methods ofSterilization Heat Dry Heat Moist Heat Steam at atmospheric pressure (100 C) Used to sterilize culture media Holding oeriod : 100 C , for 20 min on three successive days Principle : First exposoure kills vegetative bacteria and then next exposure will the vegetative bacteria that matures rom the spore.
- 16. Physical Methods ofSterilization Heat Dry Heat Moist Heat Steam under Pressure Autoclaves : • Auto clave is a device that uses steam to sterilize Equipment and other objects. • This means that all bacteria , viruses , fungi , spores are inactivated . • Principles: microorganism killed inside the autoclave is due to the temperature and high pressure help help the heat to rapidly spread within the materials. • Autoclave typically yields a temperature about 121 degree celcius, taking 15 – 20 minutes to complete the sterilization process. • Items: dressings , instruments, laboratory ware , media and pharmaceutical products
- 17. Types of steamsterilizer : Laboratory autoclave Hospital dressings sterilizer Bowl and instruments sterilizers Rapid cooling sterilizer Even domestice pressure cooker can be used as a sterilizer Disadvantage of autoclave: • Some plastics were melts in high heat • Moreover , many chemicals breakdown during the sterilization process and oily substances cannot be treated because they do not mix with water.
- 18. Filtration: It helpsto remove bacteria from heat liable liquids. Items : sera and solution of sugar or antibiotics Principle : as viruses can be pass through the ordinary filters , filtration can be used to obtain bacteria free filtrates of clinical samples for virus isolation. There are different kind of filters , available in markets for different purpose.
- 19. Radiation 2 Typesof radiation : Ionising radiation & Non–ionnising Radiation Non-ionizing radiation : Infrared – Used for rapid mass sterilization of prepacked item such as syringe, Cathaters UV Used for disinfecting enclosed areas such as Entryways, operation theatres and labs
- 20. Radiation 2 Typesof radiation : Ionising radiation & Non–ionnising Radiation Ionizing radiation : Gamma rays: X-rays Used for Sterilizing pastics, syringes, swabs, catheters, animal feeds , Cardboard , oils, fabrics and metal foils. Radiation control indicator : Special paper sticker which is yellow in colour, is sticked on the articles. After proper sterilization disc colour changes to red.
- 21. Chemical methods ofSterilization Chemical Agents Action of chemical agents : Protein Coagulation Disruption of cell membrane resulting in exposure, damage or loss of cell contents Removal of sulfhydryl group for normal functioning of enzyme Substrate competition.
- 22. Commonly used chemicals Alcohol : Frequently used are Ethyl Alcohol, Isopropyl alcohol These must be used at concentration of 60- 90 %. 70% Isopropyl alcohol can kill covid-19. Isopropyl alcohol used in disinfection of clinical thermometer. Methyle alcohol is effective against fungal spore, treating cabinets and incubators. Methyl alcohol is also toxic and inflammable.
- 23. Commonly used chemicals Aldehyde : Formaldehyde: Having bactericidal, sporicidal and lethal effect on Viruses Used to preserve anatomical specimens, destroying anthrax spore on the hair and wool.
- 24. Commonly used chemicals Glutaldehyde : Effective against tubercle bacilli, fungi,viruses. It is used to treat Anaesthetic rubber Face mask Plastic endotracheal tubes Metal instruments
- 25. Commonly used chemicals Dyes: Colored compound that chemically bonds to the substrate (DNA complexes ) of organisms and destroy the reproductive capacity of the cell. Eg. Aniline dye Aniline dye is more effective on gram +ve bacteria then gram –ve bacteria.
- 26. Commonly used chemicals Halogens : Iodine : Used as skin disinfectant Having active bactericidal activity & moderate action on spores. Chlorine : used to disinfect water supplies, swimming pools and food and dairy industry Hypochlorides are both bactericidal and also act on viruses.
- 27. Commonly used chemicals Phenols : These are obtained from distillation of coal tar between 170- 270 C Effects: Capcity to cause cell membrane damage , releaseing cell contents and causeing cell lysis. Low concentration will precipitate protein.
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- 29. EthyLene Oxide Ethyleneoxide (also known as ETO ) is a low temperature gaseous process widely used to sterilize a variety of health care products such as single-use medical devices. Products commonly processed with ethylene oxide includes: Assembled complex devices Catheters Equipment with integrated electronics Multi lumen tubing products Wound care dressings Action is due to its alkylating the amino, Carboxyl hydroxyl and Sulphydryl groups in protein molecules
- 30. Formaldehyde Gas Thisis widely used for fumigation of OT and other rooms . Formaldehyde is produced by adding 150g of KMnO4 to 280 ml of formaline for every 1000 cubic feet of room volume, after closing the windows and other outlets. After fumigation , the doors should be slealed and left unopend for 48 hours.
- 31. Betapropiolactone : Productsof ketane and formaldehyde with a boiling point of 163 C Having rapid bactericidal activity but carcinogenic. Capable of killing all microorganisms and very active against viruses.
- 32. Monitoring the effectivenessof Sterilization. To ensure that sterilization has been successfully done , indecators have been developed to monitor the effectiveness of sterilization by measuring various aspects of the process through different indicators. Mechanical indicators Chemical indicators Biological indicators
- 33. Ideal Disinfectant shouldbe : Effective against all microorganisms Be active in presence of organic matter Effective in acidic and alkaline media Have Speedy action Have high penetrating power. Compatible with other antiseptics and disinfectants Not cause local irritation. Not interfare with healing Not toxic if absorbed into circulation Inexpensive and easily available.
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