The thoroughness of sterilization is limited by the sterilization time and the strength of sterilization agent. The resistance of microorganisms to disinfectants depends on the original population density, strains or the resistance given by the environment. Sterilization is a necessary condition to obtain pure culture, and it is also a necessary technology in food industry and medicine field.
Chinese name: sterilization mbth: sterilization major: agricultural pinyin: mièjn explanation: killing microorganisms by physical and chemical methods is applicable to industries: food/medical definition, microorganisms, sterilization principle, basic requirements, method selection, sterilization method, method overview, thermal sterilization, dry heat sterilization, moist heat sterilization, intermittent sterilization, radiation sterilization, osmotic pressure sterilization, chemical reagent sterilization, specific operation, overview, heating. Definition sterilization refers to killing all microorganisms, including pathogenic and non-pathogenic microorganisms and spores, by physical or chemical methods, so as to achieve the level of sterility assurance. Articles that are not contaminated after sterilization are called sterile articles. The uncontaminated area after sterilization is called sterile area. Chapter VII Supplementary Provisions Article 36 of the Measures for the Administration of Hospital Infection (Order No.48 of the Ministry of Health) (2006) Meaning of the following terms in these Measures: (5) Sterilization: killing or eliminating all microorganisms in the medium, including pathogenic microorganisms and non-pathogenic microorganisms, including bacterial spores and fungal spores. At the same time, sterilization can also be regarded as a process, so it is defined as follows in GBT 19974-2005 "Characteristics of sterilization factors of medical care products and general requirements for setting, confirmation and routine control of sterilization process of medical devices": 3.25 The process of sterilization is used to make products free of live bacteria. The resistance of microorganisms to sterilization depends on the original population density, strains or environmental resistance. Sterilization is a necessary condition to obtain pure culture, and it is also a necessary technology in food industry and medicine field. Kill or remove the vegetative cells and spores of all microorganisms in culture medium, fermentation equipment or other targets, so as to realize aseptic process. The sterilization principle basically requires that the reused medical instruments, appliances and articles should be cleaned before disinfection or sterilization. Medical instruments, appliances and articles contaminated by prions, gas gangrene and sudden infectious diseases with unknown causes shall comply with the provisions of chapter 1 1 of WS/T 367. Heat-resistant and moisture-proof surgical instruments should be sterilized by pressure steam first, and chemical disinfectants should not be used for soaking sterilization. The environment and the surface of objects are generally cleaned first and then disinfected; When contaminated by the patient's blood and body fluids, the pollutants should be removed first, and then cleaned and disinfected. Disinfection products used in the disinfection work of medical institutions shall be approved by the administrative department of health or conform to the corresponding standards and technical specifications, and follow the approved scope, methods and precautions. Selection of methods According to the risk of infection caused by contaminated articles, the corresponding disinfection or sterilization method should be selected: 1) High-risk articles should be sterilized; 2) For articles with medium risk, the disinfection method with medium disinfection effect should be adopted; 3) Low-level disinfection method or cleaning treatment should be adopted for low-risk articles; In case of contamination by pathogenic microorganisms, choose effective disinfection methods according to the types and quantities of contaminated microorganisms on the articles: 1) For articles contaminated by pathogenic spores, fungal spores, mycobacteria and pathogens spread by scholars, high-level disinfection or sterilization should be adopted; 2) For articles contaminated by pathogenic microorganisms such as fungi, hydrophilic viruses, spirochetes, mycoplasma and chlamydia. , disinfection methods above the medium level should be adopted; 3) For articles contaminated by common bacteria and lipophilic viruses, medium or low level disinfection methods 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 extended; 5) When the microbial pollution on the disinfected articles is particularly serious, the dosage of disinfectant should be increased and/or the disinfection time should be prolonged; Sterilization method 1) pressure steam sterilization should be the first choice for heat-resistant and moisture-proof medical instruments, appliances and articles; Heat-resistant oil and dry powder should be sterilized by dry heat; 2) For heat-resistant and moisture-proof articles, low-temperature sterilization methods such as ethylene oxide sterilization, hydrogen peroxide low-temperature plasma sterilization or low-temperature formaldehyde steam sterilization should be adopted; 3) When disinfecting the surface of articles, the surface properties should be considered, and the smooth surface should be wiped with a suitable disinfectant or irradiated at close range with an ultraviolet sterilizer; The surface of porous materials should be disinfected by soaking or spraying. Methods Summarize the commonly used sterilization methods, such as chemical reagent sterilization, radiation sterilization, dry heat sterilization, wet heat sterilization and filtration sterilization. According to different needs, different methods can be adopted, such as wet heat sterilization for medium and filtration sterilization for air. Thermal sterilization Thermal sterilization uses high temperature to denature all the protein in microbial cells, and the enzyme activity disappears, leading to cell death. There are usually dry heat, wet heat and intermittent heating sterilization methods. Dry heat sterilization flame combustion method or hot air sterilization method in oven is called dry heat sterilization. Put metal instruments or cleaned glassware into an electric oven and keep it at 150 ~ 170℃ for 1 ~ 2 hours to achieve the purpose of complete sterilization (including bacterial spores). Incineration or combustion is the most thorough dry heat sterilization method, and its application scope is limited to the sterilization of inoculation rings and needles or the incineration of materials with pathogenic bacteria and animal carcasses. Wet heat sterilization is sterilization by boiling water, steam and steam pressure. Pasteurization: It was first used by French microbiologist Pasteur to disinfect fruit wine, hence its name. This is a low-temperature disinfection method for liquid flavor foods or seasonings which are not suitable for high-temperature sterilization, such as milk, beer, fruit wine or soy sauce. Pasteurization is moist heat sterilization, and there are two ways: ① classical low temperature sterilization (LTH): treatment at 665 438+0.7 ~ 62.8℃ for 30 minutes; ② Modern high temperature transient method (HTST): treatment at 765438 0.6℃ or slightly higher temperature for 65438 05 minutes. Among the above methods, steam pressure sterilization has the best effect. Normal pressure steam or high pressure steamer (generally 1 kg/cm2) can be used for sterilization. The steam temperature can reach 12 1℃, and all heat-resistant spores can be killed within 30 minutes. However, for some substances that are easily destroyed by high pressure, such as some sugars or organic nitrogen-containing compounds, the pressure sterilization of 0.6 kg/cm2 (1 10℃) 15 ~ 30 minutes is appropriate. Boiling disinfection method: generally, drinking water is disinfected by boiling at 100℃ for several minutes. Intermittent sterilization Intermittent sterilization is a steam sterilization method once a day for 3 consecutive days. This method is suitable for substances that cannot bear the temperature above 100℃ and some saccharides or protein substances. Generally, steam is used for sterilization at normal atmospheric pressure 1 hour. The sterilization temperature does not exceed 100℃, which will not damage substances such as sugar, but can kill spores germinated during intermittent culture, thus achieving the purpose of complete sterilization. Radiation sterilization Radiation sterilization is a method of sterilization by radiation under certain conditions. Commonly used are ultraviolet rays, and ionizing radiation (rays accelerate neutrons, etc.). ). Lasers with wavelengths between 25,000 and 80,000 nanometers also have strong bactericidal ability, and the wavelength of 26,500 nanometers is the most effective. Radiation sterilization is limited to a certain material, and it is difficult to be widely used because of the complex equipment required. Osmotic pressure sterilization Osmotic pressure sterilization is a method of sterilization with high osmotic pressure solution. In high-concentration salt or sugar solution, cells are separated from the plasma wall due to dehydration, and normal metabolism cannot be carried out, resulting in microbial death. Sterilization with chemical reagents Most chemical reagents have bacteriostatic effect at low concentration and bactericidal effect at high concentration. Commonly used are 5% carbolic acid, 70% ethanol and ethylene glycol. Chemical disinfectants must be volatile in order to remove residual drugs from sterilized materials. The commonly used reagents for chemical sterilization include surface disinfectants and antimetabolites (sulfonamides, etc. ), antibiotics and biopharmaceuticals. Antibiotics are secondary metabolites or artificial derivatives synthesized by microorganisms or other organisms in the process of life activities. They can inhibit or infect the life activities of other organisms (including pathogens, viruses, cancer cells, etc. ) at very low concentrations, so they can be used as excellent chemotherapeutic agents. Overview of specific operations sterilization can be called removing or killing all microorganisms in a substance. As far as general sterilization methods are concerned, the following sterilization methods can be used alone or in combination according to the types of microorganisms, the pollution situation and the nature and state of contaminated items. Whether sterilization is achieved is usually judged by sterility test. It must be confirmed whether the temperature and pressure during sterilization operation are suitable for sterilization conditions. After the sterilization conditions are selected, the sterilization effect should be confirmed to ensure that the various sterilization conditions used are suitable for the target bacteria to be killed. Heat sterilization adopts heat sterilization method. Under the specified sterilization conditions such as temperature and pressure, a certain heating time is needed. Because the nature of sterilized articles and the volume of sterilized containers are different, the sterilization time is calculated from the time when all containers reach the specified temperature. 1, flame sterilization is a method of killing microorganisms by flame heating. This method is mainly based on gas, and is used for the manufacture of magnetism and metals, as well as articles that will not be damaged in flames. The heating time in a torch or alcohol flame is usually more than two seconds. 2. Dry heat sterilization is a method of killing microorganisms by heating with dry heat air. The method mainly uses gas, and is used for magnetic and metal articles, fiber articles, mineral oil, fat, grease, experimental drugs, solid drugs and other high-temperature resistant articles; Gas and electric energy directly heat the air, and the heated air circulates and keeps dry and high temperature. Generally, sterilization is carried out under the following conditions. 135℃ ~145℃ for 3 ~ 5 hours; 160℃ ~170℃ for 2 ~ 4 hours; 180℃~ 200℃0.5 ~ 1 hour; Above 200℃ for more than 0.5 hours. Medicine, aqueous solution, etc. Put it in a sealed container. These articles are resistant to high temperature, and can be sterilized by heating with hot air at 134℃ ~ 138℃ for more than 3 minutes. 3. High pressure steam sterilization is a method to kill microorganisms by heating saturated steam with appropriate temperature and pressure. This method takes gas as heat source and is used for sterilization of magnetism, metal, rubber, paper and fiber products, water, culture medium, experimental drugs, experimental liquids and liquid medicines. In short, it is used for articles resistant to high temperature and high pressure water vapor. In order to achieve the purpose of sterilization, the original air in the sterilization container should be excluded from the exhaust during operation, and high-pressure steam must be filled during sterilization. Sterilization can usually be carried out under the following conditions. 1 15℃(0.7kg/cm2； ) 30 minutes; 12 1℃( 1.0kg/cm2； ) 20 minutes; 126℃( 1.4kg/cm2； ) 15 minutes. 4. Circulating steam sterilization method, which uses directly heated circulating steam to kill microorganisms. In this method, gas is used as a heat source to sterilize magnetic, metal, rubber and fiber articles, water, culture medium, test drugs, test liquids and liquid drugs. Sterilization with dry heat or high-pressure steam is in danger of deterioration, so it takes 30 ~ 60 minutes to sterilize in circulating steam at 100℃. 5. Boiling sterilization is a method of heating in boiling water to kill microorganisms. In this method, gas is used as an energy source to disinfect articles made of magnetism, metal, rubber and fiber, water, culture medium, test drugs, test liquids and liquid drugs, and articles disinfected by dry heat disinfection and high-pressure steam disinfection are in danger of deterioration. Therefore, in order to increase the sterilization effect, 1-2% sodium bicarbonate can be added to the boiled water. When articles are soaked in boiling water for sterilization, the boiling time should be longer than 15 minutes. 6. Step-by-step sterilization: water or circulating steam at 80℃ ~ 65438 000℃ is used for 24 hours, and heating is repeated for 3-5 times every 30-60 minutes; The main methods used to kill microorganisms. Repeated heating with water at 60℃ ~ 80℃ is also an intermittent low-temperature sterilization method. This method is mainly used for rubber products, culture media, experimental drugs, liquids and liquid drugs. Filtration sterilization Filtration sterilization is a common sterilization method, that is, microorganisms are removed by physical means such as screening or adsorption of filter materials. For heat-resistant liquids, filtration is the only practical sterilization method. Filters can be divided into two categories: deep-seated type and sieving type. Deep filtration mainly depends on the depth of filter material, and it is filtered by mechanical capture or random adsorption. Most filter materials belong to this type. Screen filters physically screen liquids or gases. Some materials that need sterilization cannot be heated, such as many vitamin solutions. Therefore, many liquids can be sterilized by filtration. Filtering does not kill microorganisms, but excludes them. There are two kinds of equipment for filtration and sterilization, one is called deep filter, such as sintered glass, unglazed ceramic particles or asbestos pressed filter plate, and the other is filtration membrane. The deep filter has been used for more than 0/00 years, and it tends to be gradually replaced by membrane filter. However, because a large number of sediments are easy to block the membrane filter, deep filtration is generally used to remove large particles first. Filtration membranes are usually made of synthetic fiber materials, such as cellulose acetate, cellulose nitrate, polycarbonate and polyvinylidene fluoride. The pore size of the filter membrane is generally 0.2 micron, which can filter out the vegetative cells of most microorganisms. The biggest disadvantage of filtration method is that it can't filter out viruses. The whole method is mainly used for gas, water, culture medium containing soluble and unstable substances, test solution and liquid medicine. Commonly used filtration devices include membrane filter, magnetic filter, glass fiber filter, etc. Radiation sterilization 1, radiation sterilization, including radioisotopes, is a method of killing microorganisms by using gamma rays generated by radioactive sources. This method is mainly used for anti-radiation articles such as glass products, magnetic products, metal products, rubber products, plastic products and fiber products. Commonly used radioactive sources are 60CO, 137C5, etc. According to the material, nature and pollution status of the articles to be sterilized, the amount of irradiation bus is adjusted to achieve the purpose of sterilization. 2. Ultraviolet sterilization is a method to kill microorganisms by irradiating ultraviolet rays. This method is mainly used for glass products, metal products, rubber products, plastic products and fiber products. , and can also be used for facilities, equipment, water or medicines. These articles have a good tolerance to ultraviolet rays. Generally, ultraviolet rays of 200-300 nm are generally used. 3. High-frequency sterilization is a method of directly killing microorganisms by high-frequency heat irradiation. This method is mainly used for water, culture medium, test solution, liquid medicine and other items that can withstand high-frequency irradiation. Frequencies of 9 15 or 2450 megacycles are usually used. Chemical sterilization 1, gas sterilization, a method of killing microorganisms by using ethylene oxide or formaldehyde. This method is mainly used for glass products, magnetic products, metal products, rubber products, plastic products, fiber products and so on. And for facilities, equipment or powdered drugs, etc. When gas sterilization is used, as a prerequisite, the sterilized items will not deteriorate. 2, liquid medicine sterilization method, is a method of killing microorganisms with liquid medicine. This method is mainly used for the sterilization of glass products, magnetic products, metal products, rubber products, plastic products, fiber products, etc. It can also be used for disinfection of fingers, aseptic boxes or aseptic equipment. Sterilization of liquid medicine is used for articles that have not deteriorated. Commonly used are ethanol (alcohol) 0. 1- 1w/v% salt benzene solution, cresol, phenol water or formalin water. For aseptic operation after sterilization, the above-mentioned used instruments or materials shall be sterilized in an aseptic box or aseptic equipment. The above sterilization methods are mainly used for pharmaceutical preparation, filling, sealing and other technological operations, and the operation speed is fast. The advanced technology of 265438+20th century is 300-600Mpa ultra-high pressure sterilization. It is internationally recognized that the application equipment of this technology is expensive, and China mainly relies on imports, which has caused the bottleneck of the application of ultra-high pressure technology. Few domestic enterprises have started to produce ultra-high pressure equipment, and it is expected that the bottleneck of expensive imports will be broken in 20 12. Sterilization parameters The verification of sterilization equipment is to verify the reliability of sterilization method through relevant parameters. 1, D value D value refers to the sterilization time required to kill 90% microorganisms (or the residual rate is 10%) at a certain temperature. Under certain sterilization conditions, different microorganisms have different D values. The same microorganism has different D values under different sterilization conditions. Therefore, the value of d varies with microbial species, environment and sterilization temperature. 2.Z value Z value refers to the increased temperature required to reduce the sterilization time to the original110 or kill 99% of microorganisms in the same sterilization time. 3.F value F value is the equivalent sterilization time at a certain temperature (t) when the sterilization effect produced by a given z value is the same as that produced by a given z value at the reference temperature (T0), and the unit is min. F value is often used for dry heat sterilization. 4. F0 value F0 value is a certain sterilization temperature (t), and the sterilization effect when z is 10℃ is the same as that when z is 12 1℃ (minutes). That is to say, no matter how the temperature changes, at 12 1℃, the sterilization effect of t minutes is equivalent to F0 minutes. F0 is only used for moist heat sterilization. Dry heat sterilization (1) dry baking: using a drying oven, heating at 160 ~ 180℃ for 2 hours can kill all microorganisms, including spores. Mainly used for sterilization of glassware and porcelain.
(2) cauterization and incineration: cauterization is the direct use of flame to kill microorganisms, which is suitable for sterilization of metal equipment that is not afraid of heat, such as inoculation needles in microbiology laboratories. Incineration is a thorough disinfection method, but it is limited to the treatment of waste pollutants, such as useless clothes, paper and garbage. Incineration shall be carried out in a special incinerator.
(3) Infrared: Infrared radiation is an electromagnetic wave with a wavelength of 0.77 ~ 1000 micron, which has a good thermal effect, especially the electromagnetic wave with a wavelength of 1 ~ 10 micron. It is also considered as a dry heat sterilization. Infrared light is generated by an infrared bulb, which does not need air conduction, so the heating speed is fast, but the thermal effect can only be generated on the irradiated surface, so an object cannot be heated evenly. The sterilization effect of infrared ray is similar to that of dry heat, and the temperature and time required for infrared oven sterilization are the same as that of dry drying. Mainly used for sterilization of medical instruments.
People who have been exposed to infrared rays for a long time will feel eye fatigue and headache; Long-term radiation can cause intraocular damage. Therefore, the staff should at least wear protective glasses that can prevent infrared damage.
(4) Microwave: Microwave is an electromagnetic wave with a wavelength of about 1m ~ 1m, which has a high frequency and can penetrate glass, plastic films and ceramics, but not metal surfaces. Microwave can make chaotic polar molecules in the medium move back and forth according to the wave frequency under the action of microwave field, collide with each other to generate heat, and the temperature of the medium can also rise accordingly, so it can play a disinfection role at a lower temperature. It is generally believed that its sterilization mechanism has electromagnetic vibration effect and field force effect besides thermal effect. There are two kinds of microwaves commonly used for disinfection: 2450MHZ and 9 15MHZ. Microwave radiation is mainly used in food processing. It can be used for disinfection of laboratory supplies, non-metallic instruments, tableware, medicine cups and other supplies in the aseptic ward of the hospital.
Long-term microwave irradiation can cause systemic reactions such as lens opacity, testicular damage and neurological dysfunction, so the door must be closed before starting the operation. Wet heat sterilization (1) boiling method: 100℃ boiling for 5 minutes can kill the propagules of general bacteria. Many spores need to be boiled for 5-6 hours before they die. Adding 2% sodium carbonate to water can raise the boiling point of water to 105℃. It can not only promote the killing of spores, but also prevent metal utensils from rusting. Boiling method can be used for disinfection of drinking water and general instruments (knives and scissors, syringes, etc.). ).
(2) Circulating steam sterilization method: using steam around 100℃ for disinfection, generally using a circulating steam sterilizer (the principle is equivalent to the steamer in China), heating 15 ~ 39 minutes, the bacterial propagule can be killed. The packaging of disinfection articles should not be too big or too tight, which is beneficial to vapor permeation.
(3) Step-by-step sterilization: steam is repeatedly circulated to achieve the purpose of sterilization. Generally, a steam sterilizer is used to kill the vector by heating at 100℃ for 15 ~ 30 minutes. But there are still spores left. Take it out and put it in an incubator at 37℃ overnight to make the spores develop into propagules, and steam it again the next day for more than three consecutive times. This method is suitable for the sterilization of nutrients (such as serum culture medium) that are not resistant to high temperature.
(4) Pasteurization: an edible method that uses heat to kill pathogenic bacteria or general miscellaneous bacteria in liquid without seriously damaging its quality. It was invented by Pasteur to disinfect alcohol, hence its name. Heat 6 1. 1 ~ 62.8℃ for half an hour, or 7 1.7℃ 15 ~ 30 minutes. Commonly used to disinfect milk and alcohol.
(5) High-pressure steam sterilization method: High-pressure steam sterilization is carried out in a special high-pressure steam sterilizer, which is the most widely used and reliable method in thermal sterilization. Its advantages are strong penetrating power and reliable sterilization effect, and it can kill all microorganisms.
The pressure sterilizers used can be divided into two categories: low exhaust pressure sterilizers and pre-vacuum pressure sterilizers. Suitable for sterilization of high-temperature and water-resistant articles.