Sterilization techniques .TYPES .MERTIES. AND DIMERTIES AND APPLICATION......
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This document discusses sterilization techniques. It defines sterilization as any process that eliminates transmissible agents like bacteria and viruses. The main methods of sterilization discussed are physical (heat, radiation, filtration) and chemical (gaseous). Heat sterilization through moist heat like autoclaving and dry heat is the most widely used method. Radiation uses gamma rays or electrons to sterilize heat-sensitive products. Filtration removes microbes from liquids and gases. Gaseous sterilization uses chemicals like ethylene oxide or formaldehyde that react with microbes. Sterilization is important in medicine to prevent disease transmission and growth and avoid additional surgeries.
Sterilization techniques .TYPES .MERTIES. AND DIMERTIES AND APPLICATION......
- 1. STERILIZATION TECHNIQUES s.palaniananth microbiology B.Sc biotechnology III RD YEAR Alpha arts and science college
- 2. CONTENT WHAT IS STERILZATION ? METHODS OF STERILIZATION IMPORTANCE OF STERILIZATION ADVANTAGES AND DISADVANTAGES WHY NEEF OF STERILIZATION
- 3. WHAT IS STERILZATION ? Sterilization can be defined as any process that effectively kills or eliminates transmissible agents (such as fungi, bacteria, viruses and prions) from a surface, equipment, foods, medications, or biological culture medium
- 4. METHODS OF STERILZATION The various methods of sterilization are: 1. Physical Method Thermal (Heat) methods Radiation method Filtration method 2. Chemical Method • Gaseous method
- 5. PHYSICAL METHODS: HEAT STERILIZATION: Heat sterilization is the most widely used and reliable method of sterilization, involving destruction of enzymes and other essential cell constituents. This method of sterilization can be applied only to the THERMO STABLE PRODUCTS, but it can be used for MOISTURE-SENSITIVE MATERIALS. i) Dry Heat (160-1800˚C) Sterilization for thermo stable products ii) moist heat (121-1340 ˚C) sterilization is used for moisture- resistant materials.
- 6. The efficiency with which heat is able to inactivate microorganisms is dependent upon i) the degree of heat, the exposure time and ii) the presence of water. The action of heat will be due to induction of lethal chemical events mediated through the action of water and oxygen. In the presence of water much lower temperature time exposures are required to kill microbe than in the absence of water.
- 7. THERMAL (HEAT) METHODS Thermal methods includes: Dry Heat Sterilization Ex: 1.Incineration 2. Red heat 3. Flaming 4. Hot air oven Moist Heat Sterilization 1.Dry saturated steam –Autoclaving 2. Boiling water/ steam at atmospheric pressure 3. Hot water below boiling point
- 8. Dry Heat Sterilization It employs higher temperatures in the range of 160- 180˚C and requires exposures time up to 2 hours, depending upon the temperature employed. The benefit of dry heat includes good penetrability and non-corrosive nature which makes it applicable for sterilizing glass wares and metal surgical instruments. It is also used for sterilizing non- aqueous thermo stable liquids and thermo stable powders. Dry heat destroys bacterial endotoxins (or pyrogens) which are difficult to eliminate by other means and this property makes it applicable for sterilizing glass bottles which are to be filled aseptically
- 9. Moist Heat Sterilization Moist heat sterilization involves the use of steam in the range of 121-134˚C. Steam under pressure is used to generate high temperature needed for sterilization. Saturated steam acts as an effective sterilizing agent.
- 11. Autoclave Autoclaves use pressurized steam to destroy microorganisms, and are the most dependable systems available for the decontamination of laboratory waste and the sterilization of laboratory glassware, media, and reagents. For efficient heat transfer, steam must flush the air out of the autoclave chamber. Generally the conditions employed are Temperature upto121-134˚C for 15-20 min under 15 lbs pressure,based on type of metiral used.
- 12. Auto clave:
- 13. Radiation Sterilization Many types of radiation are used for sterilization like electromagnetic radiation (e.g. gamma rays and UV light), particulate radiation (e.g. accelerated electrons).The major target for these radiation is microbial DNA. Radiation sterilization with high energy gamma rays or accelerated electrons has proven to be a useful method for the industrial sterilization of heat sensitive products. Radiation sterilization is generally applied to articles in the dry state; including surgical instruments, sutures, prostheses, unit dose ointments, plastic syringes and dry pharmaceutical products.
- 14. UV light, with its much lower energy, and poor penetrability finds uses in the sterilization of air, for surface sterilization of aseptic work areas, for treatment of manufacturing grade water, but is not suitable for sterilization of pharmaceutical dosage forms.
- 15. Filtration Sterilization Filtration process does not destroy but removes the microorganisms. It is used for both the clarification and sterilization of liquids and gases as it is capable of preventing the passage of both viable and non viable particles. The major mechanisms of filtration are sieving, adsorption and trapping within the matrix of the filter material. Ex:HEPA FILTERS
- 16. Sterilizing grade filters are used in the treatment of heat sensitive injections and ophthalmic solutions, biological products and air and other gases for supply to aseptic areas. They are also used in industry as part of the venting systems on fermentors, centrifuges, autoclaves and freeze driers. Membrane filters are used for sterility testing
- 17. There are two types of filters used in filtration sterilization: (a)Depth filters: (b) Membrane filters: These are porous membrane about 0.1 mm thick, made of cellulose acetate, cellulose nitrate, polycarbonate, and polyvinylidene fluoride, or some other synthetic material
- 18. CHEMICAL STERILIZATION METHOD : GASEOUS METHOD The chemically reactive gases such as formaldehyde, (methanol, H.CHO) and ethylene oxide (CH2)2O possess biocidal activity. Ethylene oxide is a colorless, odorless, and flammable gas. The mechanism of antimicrobial action of the two gases is assumed to be through alkylations of sulphydryl, amino, hydroxyl and carboxyl groups on proteins and amino groups of nucleic acids.
- 19. The concentration ranges (weight of gas per unit chamber volume) are usually in range of 800- 1200 mg/L for ethylene oxide and 15-100 mg/L for formaldehyde with operating temperatures of 45-63°C and 70-75°C respectively. Both of these gases being alkylating agents are potentially mutagenic and carcinogenic. They also produce acute toxicity including irritation of the skin, conjunctiva and nasal mucosa
- 20. IMPORTANCE OF STERILIZATION Medical Sterilization : Prevents the Growth of Diseases: In any medical tool/device used, bacteria comes onto it. If left unchecked or not disinfected properly, it is highly likely that bacteria will grow. Prevents the Spread of Diseases : If surgical equipment is not properly sterilized, patients treated are exposed to a disease the previous patient had. Prevents Double Surgeries : If unsterilized equipment is used, it can cause an infection leading to another surgery later on in order to remove it. This is costly and can cause many life- threatening complications.
- 22. Heat sterilization • Destroys bacterial endo toxinS MERITS Most widely used and reliable method of sterilization, involving destruction of enzymes and other essential cell constituents DIMERITS Can be applied only to the thermo stable Products APPLICATION Dry heat is applicable for sterilizing glass wares and metal surgical instruments and moist heat is the most dependable method for decontamination of laboratory waste and the sterilization of laboratory glassware, media, and reagents.
- 23. Gaseous sterilization MECHANISM : • Alkylation MERITS Penetrating ability of gases. DIMERITS Gases being alkylating agents are potentially mutagenic and carcinogenic APPLICATION : • ETHYLEN GAS HAS been used widely to process heat-sensitive devices
- 24. Radiation sterilization : MECHANCISM • Ionization of nucleic acids MERITS • It is a useful method for the industrial sterilization of heat sensitive products DIMERITS • Undesirable changes occur in irradiated products,an example is aqueous solution where radiolysis of water occurs. APPLICATION • Radiation sterilization is generally applied to articles in the dry state; including surgical instruments, sutures, prostheses, unit dose ointments, plastic
- 25. Filtration sterilization : MECHANISM Does not destroy but removes the microorganisms MERTIS: It is used for both the clarification and sterilization of liquids and gases as it is capable of preventing the passage of both viable and non viable particles DIMERTIS Does not differentiate between viable and non viable particles APPLICATION This method is Sterilizing grade filters are used in the treatment of heat sensitive injections and ophthalmic solutions, biological products and air and other gases for supply to aseptic areas
- 26. Why we need Sterilization ? Microorganisms capable of causing infection are constantly present in the external environment and on the human body. Microorganisms are responsible for contamination and infection. The aim of sterilization is to remove or destroy them from materials or from surfaces.
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