The measure of using strong physical and chemical factors to make all microorganisms inside and outside any object permanently lose their ability to grow and reproduce is called sterilization. Commonly used methods of sterilization include chemical reagent sterilization, ray sterilization, dry heat sterilization, moist heat sterilization and filter sterilization. Can be based on different needs, using different methods, such as media sterilization generally use moist heat sterilization, air is used to filter sterilization.
The thoroughness of sterilization is governed by the sterilization time and the strength of the sterilizing agent. The resistance of microorganisms to the sterilizing agent depends on the density of the original population present, the strain, or the resistance given to the strain by the environment. Sterilization is a necessary condition to obtain a pure culture, and is also a necessary technology in the food industry and pharmaceutical field.
Basic introduction Chinese name ：sterilization Foreign name ：sterilization Specialty ：Agricultural science Pinyin ：miè jūn Explanation ： Killing microorganisms by physicochemical methods Applicable industry ：Food/Medicine Definition,Microorganisms,Principles of Sterilization,Basic Requirements,Selection of Methods,Methods of Sterilization,Overview of Methods,Thermal Sterilization Methods,Dry Heat Sterilization,Moisture Sterilization,Intermittent Sterilization,Radiation Sterilization. Osmotic Pressure Sterilization, Chemical Reagent Sterilization, Specific Operations, Overview, Heat Sterilization, Filtration Sterilization, Irradiation Sterilization, Chemical Sterilization, Aseptic Operation, Sterilization Parameters, Dry Heat Sterilization, Moist Heat Sterilization, Definition Sterilization refers to the use of physical or chemical methods to kill all microorganisms, including pathogenic and non-pathogenic microorganisms as well as the germs, so that they reach the level of sterility assurance. Sterilized items that are not contaminated are called sterile items. After sterilization, the area that is not contaminated is called sterile area. Measures for the Management of Hospital Infections (Ministry of Health Decree No. 48) (2006) Chapter VII Supplementary Provisions Article 36 Meaning of the following terms in these Measures: (e) Sterilization: killing or eliminating all microorganisms on the medium of transmission, including pathogenic microorganisms and non-pathogenic microorganisms, but also bacterial germ cells and fungal spores. At the same time, sterilization can be viewed as a process, so in the "GBT19974-2005 health care products sterilization Sterilization factor characteristics and general requirements for the setting, confirmation and routine control of the sterilization process of medical devices" has the following definitions: 3.25 Sterilization Sterilization Process used to make the product free of viable microorganisms Microorganisms Microorganisms resistant to sterilizing agents depend on the The resistance of microorganisms to a sterilizing agent depends on the density of the original population present, the strain, or the resistance conferred on the strain by the environment. Sterilization is essential for obtaining pure cultures and is a necessary technique in the food industry and medicine. The process of killing or removing all trophic cells of microorganisms and their germ cells (or spores) from a culture medium, fermentation equipment, or other target, thereby achieving sterility. Principles of Sterilization Basic Requirements Repeatedly used diagnostic and therapeutic instruments, appliances, and items should be cleaned after use before they are disinfected or sterilized. Diagnostic and therapeutic instruments, apparatus and articles contaminated by prions, gas gangrene and sudden and unexplained infectious disease pathogens should implement the provisions of Chapter 11 of WS/T 367. Heat-resistant, moisture-resistant surgical instruments, should be preferred to pressure steam sterilization, should not take chemical disinfectant immersion sterilization. The environment and the surface of objects, in general, should be cleaned first, then disinfected; when contaminated by patients' blood, body fluids, etc., the pollutants should be removed first, then cleaned and disinfected. Disinfection products used in the disinfection work of medical institutions should be approved by the administrative department of health or in accordance with the corresponding standard technical specifications, and should follow the approved scope of use, methods and precautions. Selection of methods Select the appropriate disinfection or sterilization methods according to the risk of infection caused by contaminated items: 1) high-risk items should be treated by sterilization; 2) medium-risk items should be treated by disinfection methods that achieve the effect of medium-level disinfection or above; 3) low-risk items should be treated by low-level disinfection methods or cleaned; in case of contamination by pathogenic microorganisms, select effective disinfection methods according to the pathogenic microorganisms contaminated. Select effective disinfection methods according to the types and quantities of contaminated microorganisms on the articles. 1) For articles contaminated with pathogenic bacterial spores, fungal spores, mycobacteria and pathogens transmitted by the school, high level disinfection or sterilization should be adopted; 2) For articles contaminated with pathogenic microorganisms such as fungi, hydrophilic viruses, spirochetes, mycoplasmas, chlamydia and other pathogenic microorganisms, medium level disinfection or above disinfection methods should be adopted. or above; 3) For articles contaminated by general bacteria and lipophilic viruses, etc., disinfection methods up to medium level or low level should be adopted; 4) When killing microorganisms protected by organic matter, the dosage of disinfectant should be increased and/or the disinfection time should be prolonged; 5) When microorganisms contamination on the disinfected articles is particularly serious, the dosage of disinfectant should be increased and/or the disinfection time should be prolonged; Sterilization Methods 1) Heat-resistant, moisture-resistant diagnostic and therapeutic instruments, appliances and articles, should be preferred to pressure steam sterilization; heat-resistant oils and dry powders should be sterilized by dry heat; 2) non-heat-resistant, moisture-resistant articles, it is appropriate to use low-temperature sterilization methods, such as ethylene oxide sterilization, low-temperature plasma sterilization with hydrogen peroxide, or low-temperature formaldehyde steam sterilization; 3) the surface of the articles to disinfect, it is appropriate to take into account the nature of the surface, and it is appropriate to select the appropriate disinfectant for smooth surfaces to wipe or Ultraviolet sterilizer near irradiation; porous material surfaces are suitable for disinfection by immersion or spraying. Overview of methods Commonly used methods for sterilization include chemical reagent sterilization, radiation sterilization, dry heat sterilization, moist heat sterilization and filter sterilization. Different methods can be used according to different needs, such as sterilization of culture medium is generally used moist heat sterilization, and air is filtered to remove bacteria. Heat sterilization method Heat sterilization method using high temperature to make all the proteins in the microbial cell denaturation, enzyme activity disappears, resulting in cell death. Usually dry heat, moist heat and intermittent heating sterilization method. Dry heat sterilization flame burning method or oven hot air sterilization method called dry heat sterilization (dryheatsterilization). Metal instruments or washed glassware into an electric oven, maintained at 150 ~ 170 ℃ for 1 ~ 2 hours, can achieve the purpose of complete sterilization (including bacterial spores). Cauterization (incineration or combustion) is one of the most thorough dry heat sterilization method, the scope of application is limited to the inoculation ring, inoculation needle sterilization or with pathogenic materials, animal carcasses, such as burning. Moist heat sterilization Sterilization by boiling water, steam and steam pressurization. Pasteurization method: because the first French microbiologist Pasteur used for fruit wine sterilization, so the name. It is a low-temperature sterilization method dedicated to liquid flavored foods or seasonings that should not be sterilized at high temperatures, such as milk, beer, fruit wines or soy sauce. Pasteurization is moist heat sterilization, there are two ways of this method, ① the classic lowtemperatureholdingmethod (lowtemperatureholdingmethod, LTH): at 61.7 ~ 62.8 ℃ under the treatment of 30 minutes; ② the more modern high temperature transient method (hightemperatureshorttime or flushpoint. HTST): 15 min at 71.6°C or slightly higher. In the above methods, the best effect of steam pressurization, available atmospheric steam sterilization, but also in the high-pressure steam pot (generally use 1 kg / cm 2) sterilization, the steam temperature up to 121 ℃, can be heat-resistant spores in 30 minutes all killed. But for some substances that are easily destroyed by high pressure, such as some sugar or organic nitrogen compounds, it is appropriate to 0.6 kg / cm 2 pressure (110 ℃) sterilization 15 ~ 30 minutes. Boiling sterilization method: using the method of boiling at 100 ℃ for a few minutes, generally used for the disinfection of drinking water. Intermittent sterilization Intermittent sterilization is a method of steam sterilization once a day for 3 consecutive days. This method is suitable for substances that cannot withstand temperatures above 100°C and some sugar or protein substances. Generally, steam sterilization is carried out for 1 hour at normal atmospheric pressure. Sterilization temperature does not exceed 100 ° C, does not cause the destruction of sugars and other substances, but can be intermittent culture during the germination of spores to kill, so as to achieve the purpose of complete sterilization. Radiation sterilization Radiation sterilization under certain conditions using rays for sterilization methods. The more commonly used are ultraviolet rays, and other ionizing radiation (rays to accelerate neutrons, etc.). The wavelength of 25000 ~ 80000 nanometers between the laser also has a strong sterilization ability, to the wavelength of 26500 nanometers is the most effective. Radiation sterilization is limited to certain materials and is difficult to use widely because of the complexity of the equipment required. Osmotic Pressure Sterilization Osmotic Pressure Sterilization is a method that uses a high osmotic pressure solution for sterilization. In a high concentration of salt or sugar solution in the cell due to dehydration and plasma wall separation occurs, can not carry out normal metabolism, resulting in the death of microorganisms. Sterilization of chemical reagents Most of the chemicals in low concentrations play a bacteriostatic role, high concentrations play a bactericidal role. Commonly used 5% carbolic acid, 70% ethanol and ethylene glycol. Chemical sterilization agent must be volatile in order to remove the residual drug on the material after sterilization. Chemical sterilization commonly used reagents are surface disinfectants, antimetabolites (sulfonamides, etc.), antibiotics, biopharmaceuticals antibiotics are a class of microorganisms or other organisms synthesized in the course of the life of the secondary metabolites or artificial derivatives, they are in a very low concentration can be inhibited or infected with the life of its kind of organisms (including pathogens, viruses, cancer cells, etc.), and therefore used as a good chemotherapeutic agent. Specific operations Overview Sterilization can be described as the removal or killing of all microorganisms in a substance. Depending on the type of microorganism, the state of contamination, and the nature and condition of the contaminated material, the following sterilization methods can be used individually or in combination. Whether the purpose of sterilization is achieved is usually determined by the sterility test method. It is necessary to confirm whether the temperature and pressure during the sterilization operation are suitable for the sterilization conditions. After the sterilization conditions are selected, the sterilization effect is also checked to ensure that the various sterilization conditions used are suitable for the target bacteria to be killed. Heating Sterilization When using the heating sterilization method, a certain heating time should be reached under the specified sterilization conditions such as temperature and pressure. Since the nature of the sterilized items and the volume size of the sterilized containers vary, the sterilization time should be calculated from the time when all the containers have reached the specified temperature. 1, flame sterilization method, is the use of flame heating to kill microorganisms a method. This method is gas-based, for magnetic and metal mouth and in the flame will not break the items. Heating time is usually more than seconds in the flame of a blowtorch or alcohol. 2, dry heat sterilization method, is the use of dry air heating to kill microorganisms a method. This method is based on gas, used for magnetic, metal a number of items, fiber items, mineral oil, fat, fat oil, test drugs, solid pharmaceuticals and other heat-resistant items; the use of gas and electricity to directly heat the air, the heated air for circulation, to maintain a dry and high-temperature state. Usually, sterilization is performed under the following conditions. 135℃～145℃ 3～5 hours; 160℃～170℃ 2～4 hours; 180℃～200℃ 0.5～1 hour; above 200℃ 0.5 hours or more. In sealed containers filled with medicines, aqueous solutions, etc., these items are heat-resistant items, can be used 134 ℃ ~ 138 ℃ of hot air, heating for more than 3 minutes for sterilization. 3, high-pressure steam sterilization method, is the use of appropriate temperature and pressure of saturated water vapor heating to kill microorganisms a method. This approach to gas as a heat source for magnetic, metal, rubber, paper, fiber-based items, water, culture media, test drugs, test liquids and liquid pharmaceuticals, in short, for high-temperature and high-pressure water vapor-resistant items. In order to actually achieve sterilization, the original air in the sterilization container should be removed from the exhaust during operation, and the high-pressure steam must be full when sterilizing. Sterilization can usually be performed under the following conditions. 115 ℃ (0.7kg/cm 2 ;) 30 minutes; 121 ℃ (1.0kg/cm 2 ;) 20 minutes; 126 ℃ (1.4kg/cm 2 ;) 15 minutes. 4, circulation steam sterilization method, the use of direct heating of the circulation of water vapor to kill microorganisms. This method uses gas as a heat source to sterilize magnetic, metal, rubber and fiber items, water, culture media, test drugs, test liquids and liquid pharmaceuticals. With dry heat sterilization or autoclave sterilization method, the items have the risk of deterioration, so in the 100 ℃ circulation of water steam sterilization takes 30 to 60 minutes. 5, boiling sterilization method, the use of submerged in boiling water heating to kill microorganisms in a method. This method uses gas as an energy source to sterilize magnetic, metal, rubber and fiber items, water, culture media, test drugs, test liquids, liquid medicines, etc. Items sterilized by dry heat sterilization and high-pressure steam sterilization are at risk of deterioration. So in order to increase the sterilization effect, 1-2% sodium bicarbonate can be added to the boiling water. Sink the items into the boiling water for sterilization, boiling time should be more than 15 minutes. 6, intermittent sterilization method, is the use of 80 ℃ ~ 100 ℃ water or circulation of water vapor, 24 hours for a cycle, every 30 ~ 60 minutes to repeatedly heat 3-5 back; used to kill microorganisms of a main method. Repeated heating with 60 ℃ ~ 80 ℃ water is also an intermittent low-temperature sterilization method. This method is mainly used for rubber-based products, culture media, test drugs, liquid and liquid medicine. Filtration sterilization Filtration sterilization method, that is, sieve or filter material adsorption and other physical ways to remove microorganisms, is a commonly used sterilization methods. Filtration is the only practical sterilization method for heat-insensitive liquids. Filters can be divided into two categories: deep filters and sieve filters. Deep filters mainly rely on the depth of the filter media, through mechanical capture or random adsorption for filtration, most of the filter media belong to this type. Sieve type filter to physical sieve method will be in the liquid or gas . Some materials that need to be sterilized cannot be subjected to heat, such as many vitamin solutions. Therefore, many liquids can be sterilized by filtration. Rather than killing microorganisms, filtration removes them. Two types of apparatus are used for sterilization by filtration, one called deep filters, such as filter plates made of sintered glass, unglazed ceramic particles, or pressed asbestos: the other is filter membranes. Deep filter has been used for more than 100 years, there is a tendency to gradually be replaced by the membrane, but because a large number of sediments tend to clog the membrane, so generally the first deep filter to remove large particles. Filter membrane is generally made of cellulose acetate, cellulose nitrate, polycarbonate, polyvinylidene fluoride and other synthetic fiber materials. The pore size of the filter membrane is generally 0.2 microns, which can filter out the majority of microbial nutrient cells. The biggest disadvantage of the filtration method is that it cannot filter out viruses. The whole method is mainly used for gases, water, culture media containing soluble and unstable substances, test liquids and liquid pharmaceuticals. Usually used filtration devices are membrane filters, magnetic filters, glass fiber filters and so on. Irradiation sterilization 1, radiation sterilization method, including radioisotopes, including the use of gamma rays from a radioactive source for irradiation, is a method of killing microorganisms. This method is mainly used for glass products, magnetic products, metal products, rubber products, plastic products and fiber products and other items resistant to radiation. Usually use the radioactive source 60CO, 137C5, etc., according to the material of the sterilized items, traits and contamination, etc., the irradiation of the sinks and discharges are adjusted in order to achieve the purpose of sterilization. 2, ultraviolet sterilization method, is the use of irradiation of ultraviolet light to kill microorganisms of a method. This method is mainly used for glass products, metal products, rubber products, plastic products and fiber products, etc., can also be used for facilities, equipment, water or pharmaceuticals, etc., these items should be ultraviolet light has a good tolerance, usually, the general set of 200-300nm ultraviolet light. 3, high-frequency sterilization method, is directly with irradiation of high-frequency heat to kill microorganisms of a method. This method is mainly used for water, culture medium, test liquids and liquid pharmaceuticals and other items resistant to high-frequency irradiation. Usually use 915 or 2450 megacycles of frequency. Chemical sterilization 1, gas sterilization method, the use of ethylene oxide or formaldehyde sex kill microorganisms a method. This method is mainly used for glass products, magnetic products, metal products, rubber products, plastic products, fiber products, etc., for facilities, equipment or powdered medicines, etc., the use of gas sterilization, the items to be sterilized in order not to deteriorate as a prerequisite. 2, liquid sterilization method, is the method of killing microorganisms with liquid. This method is mainly used for glass products, magnetic products, metal products, rubber products, plastic products, fiber products and other items of sterilization, can also be used for fingers, sterile boxes or sterile equipment, etc., the liquid sterilization for non-deteriorated items. Usually used are ethanol (alcohol) 0.1-1w/v% salinized benzene solution, cresol, phenol water or formalin water. Aseptic operation After sterilizing the above instruments or materials that have been used, aseptic operation should be carried out in a sterile box or aseptic equipment. The above various sterilization methods are mainly used for the preparation, filling, sealing and other process operations of pharmaceutical products, and the operation speed should be fast. The 21st century cutting-edge technology 300-600Mpa ultrahigh-pressure sterilization, internationally recognized as the technology set of equipment is expensive, China relies mainly on imports, resulting in ultrahigh-pressure technology set of bottlenecks. Few domestic enterprises in the beginning of the production of ultra-high-pressure equipment, is expected to break the bottleneck of expensive imported set of bottlenecks in 2012. Sterilization parameters The verification of sterilization equipment is through the relevant parameters of the sterilization method for reliability verification. 1, D value D value refers to a certain temperature, kill 90% of the microorganisms (or residual rate of 10%) of the sterilization time required. Under certain sterilization conditions, different microorganisms have different D value; the same microorganisms in different sterilization conditions, D value is not the same. Therefore, the D value varies with the species of microorganisms, environment and sterilization temperature. 2, Z value Z value is the sterilization time is reduced to the original 1/10 of the temperature required to increase or in the same sterilization time, kill 99% of the microorganisms required to increase the temperature. 3, F-value F-value for a certain temperature (T), the sterilization effect produced by a given Z-value and the sterilization effect produced by a given Z-value at the reference temperature (T0), the equivalent sterilization time, in min. F-value is commonly used in dry heat sterilization. 4, F0 value F0 value for a certain sterilization temperature (T), Z is 10 ℃ when the sterilization effect produced by 121 ℃, Z value of 10 ℃ when the sterilization effect produced by the same equivalent time (min). In other words, regardless of temperature changes, the sterilization effect in t minutes is equivalent to the effect of sterilizing F0 minutes at 121 ℃. F0 is only used for moist heat sterilization. Dry heat sterilization (1) dry baking: the use of dry oven, heating 160 ~ 180 ℃ for 2 hours, can kill all microorganisms, including germs. Mainly used for glassware, porcelain and other sterilization.(2) cauterization and incineration: cauterization is a direct flame to kill microorganisms, suitable for microbiology laboratories, inoculation needles and other metal equipment that are not afraid of heat sterilization. Incineration is a thorough disinfection method, but is limited to the treatment of discarded contaminated items, such as useless clothing, paper, garbage and so on. Incineration should be carried out in a special incinerator.
(3) infrared: infrared radiation is a 0.77 ~ 1000 micron wavelength electromagnetic waves, has a good thermal effect, especially 1 ~ 10 micron wavelength of the strongest thermal effect. Also considered a dry heat sterilization. Infrared light generated by infrared bulbs, do not need air conduction, so the heating speed, but the thermal effect can only be generated on the surface of the irradiation, so it can not make an object before and after the left and right uniform heating. Infrared sterilization and dry heat similar to the use of infrared oven sterilization of the required temperature and time is the same as dry baking. Mostly used for sterilization of medical equipment.
People exposed to infrared radiation for a long time will feel tired eyes and headache; long-term exposure will cause damage to the eye. Therefore, workers should at least wear protective glasses against infrared damage.
(4) microwave: microwave is a wavelength of 1 millimeter to 1 meter or so of electromagnetic waves, high frequency, can penetrate glass, plastic film and ceramics and other substances, but can not penetrate the metal surface. Microwave can make the medium disordered polar molecules in the microwave field under the action of the frequency of the wave back and forth movement, mutual collision and friction and generate heat, the temperature of the medium can be increased, and thus at lower temperatures can play a role in sterilization. It is generally believed that the sterilization mechanism in addition to the thermal effect, there are electromagnetic **** vibration effect, the role of field effect. Sterilization in the commonly used microwave 2450MHZ and 915MHZ two kinds. Microwave irradiation is used for food processing. In the hospital can be used for laboratory supplies, non-metallic instruments, sterile sick room food utensils, medicine cups and other supplies disinfection.
Microwave long-term irradiation can cause eye clouding, testicular damage and neurological disorders and other systemic reactions, so the door must be closed before starting the operation. Moist heat sterilization (1) boiling method: boiling 100 ℃, 5 minutes, can kill the general bacterial propagules. Many germ cells need to be boiled tide 5 to 6 hours before death. The addition of 2% sodium carbonate to the water can raise its boiling point to 105 ℃. It promotes the killing of germ cells and also prevents rusting of metal utensils. The boiling method can be used to sterilize drinking water and general instruments (knives and scissors, syringes, etc.).
(2) circulation steam sterilization method: the use of about 100 ℃ of water vapor for disinfection, generally using circulation steam sterilizer (its principle is equivalent to our steamer), heating 15 to 39 minutes, can kill bacterial propagules. Sterilized items should not be too large, too tight to facilitate steam penetration.
(3) intermittent sterilization method: the use of repeated circulation of steam, in order to achieve the purpose of sterilization. General use of circulating steam sterilizer, 100 ℃ heating 15 ~ 30 minutes, which can kill the propagules; but the bud cells still have residual. Remove and put 37 ℃ incubator overnight, so that the germ cells develop into propagules, the next day and then steam, so more than three consecutive times. This method is applicable to the sterilization of nutrients that are not resistant to high temperature (such as serum culture medium).
(4) pasteurization (Pasteurization): the use of heat to kill pathogenic bacteria in the liquid or general bacteria, without seriously damaging the quality of the consumption method. Created by Pasteur to sterilize alcohol, hence the name. Heating 61.1 ~ 62.8 ℃ half an hour, or 71.7 ℃ 15 ~ 30 minutes. Commonly used to sterilize milk and alcohol and so on.
(5) high-pressure steam sterilization: pressure steam sterilization is carried out in a special pressure steam sterilizer, is the most common use of heat sterilization, the most reliable effect of a method. Its advantages are strong penetration, reliable sterilization effect, can kill all microorganisms.
The pressure sterilizers used can be divided into two categories: lower exhaust pressure sterilizers and pre-vacuum pressure sterilizers. It is suitable for sterilization of high temperature and water resistant items.