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Sterilization methods Know how many common physical sterilization methods
2024-11-22
2024-11-22
2024-11-22
2024-11-22
sterilization, the basic technique of microbiology to kill microorganisms in certain substances by physical and chemical methods.
The complete degree of sterilization is restricted by the sterilization time and the strength of the sterilizer.The resistance of microorganisms to bactericides depends on the density of the population originally present, the strain, or the resistance conferred by the environment on the strain.Sterilization is a necessary condition for obtaining pure culture and is an essential technology in the food industry and the pharmaceutical field.
Sterilization refers to the process of killing all microorganisms (both pathogen and non-pathogen propagules and spores) on an object.Therefore, sterilization is more demanding than disinfection;But in daily life, the terms disinfection and sterilization are often used in general.
There are many kinds of sterilization and disinfection methods, which can be divided into two categories: physical method and chemical method.
Physical methods include heating sterilization, filtration sterilization, ionizing radiation sterilization, radiation surface sterilization, etc.
Chemical method is mainly the use of inorganic or organic chemicals for disinfection and sterilization.
First, heat sterilization: the use of high temperature to denature all proteins in microbial cells, enzyme activity disappeared, resulting in cell death.
Usually there are dry heat, wet heat and intermittent heating sterilization methods.
1. Dry heat sterilization: direct use of flame to burn microorganisms (such as burning inoculation rings, slides and tube mouths, etc.).Items that cannot be sterilized with flame are sterilized with hot air, and the items are heated in the oven to 160 ~ 170 ° C for 90 minutes, this method is suitable for glass, metal and wood utensils.Suitable for high temperature resistant but not suitable for humid heat sterilization.
2. Wet heat sterilization: sterilization with boiling water, steam and steam pressure.
2.1 Pasteurization is moist heat sterilization. There are two ways of pasteurization.
(1) Low temperature long-term treatment: treatment at 61.7 ~ 62.8℃ for 30 minutes;
(2)High temperature short time treatment: treatment at 71.6℃ or slightly higher temperature for 15 minutes.
2.2 Autoclave sterilization - the most reliable sterilization method: 115℃*30min or 121.5℃*20min or 126.5℃*15min.
Application: high temperature, high pressure steam resistant pharmaceutical preparations, glass/metal containers, porcelain, rubber plug, filter membrane filter
2.3 Circulating steam sterilization method: circulating steam at 100℃ for 30 ~ 60min.
Application: disinfection, not resistant to high heat preparation sterilization
2.4 Boiling sterilization method: boiling water, 30 ~ 60min.
Application: Sterilize syringe and injection needle, add antibacterial agent if necessary
3. Intermittent sterilization: Steam sterilization is carried out once a day for 3 consecutive days.
This method is suitable for substances that can not withstand temperatures above 100 ° C and some sugars or proteins.
The fungus to be destroyed was heated in water or steam at 60 ~ 80℃ for 60min to kill the propagules → placed for 24h, and the remaining spores developed into propagules → reheated and sterilized, placed → repeated for many times until all the spores were killed.
Application: sterilization of heat-sensitive materials/preparations that are not resistant to high temperature, adding bacteriostatic agents if necessary.
2. Radiation sterilization
Radiation sterilization is the use of gamma rays to kill bacteria.
Commonly used 60Co radiation source radiation gamma ray sterilization, the temperature of the sterilized items only a few degrees of change, the mechanism of sterilization is that gamma rays directly act on microbial proteins, nucleic acids and enzymes, etc., to promote the chemical bond break, kill microorganisms;
It can also indirectly act on water molecules in microorganisms, causing ionization and excitation of water, generating free radicals, and then acting on microbial active molecules, causing microbial death.
Because of its strong penetration, gamma rays can be used to seal and sterilize entire boxes of packaged drugs.
The sterilization effect is reliable.
It is generally believed that the dose of radiation below 10 thousand grays (KGY) for proprietary Chinese medicine can meet the requirements of health standards.
1, radiation sterilization: radioactive isotope (60Co or 137Cs) radiation gamma ray sterilization method.
It is characterized by strong penetration without increasing the temperature of the product.
It is suitable for sterilization of heat-resistant drugs, such as vitamins, antibiotics, hormones, heparin, catgut, important preparations, medical devices, polymer materials, etc.
Chinese Pharmacopoeia (2000 edition) has included this method.
2, microwave sterilization method: refers to the use of microwave irradiation to produce heat and kill microorganisms.
Microwaves with frequencies between 300 megahertz and 300 gigahertz can be absorbed by water, and the water molecules spin and friction to generate heat.
It is characterized by low temperature, time-saving (2-3min), atmospheric pressure, uniformity, high efficiency, long shelf life, energy saving, no pollution to the environment, simple operation and easy maintenance.
Suitable for sterilization of water-based injection.
However, there are some problems such as incomplete sterilization and labor protection.
3, ultraviolet sterilization method: the general wavelength of 200-300nm ultraviolet can be used for sterilization, the strongest sterilization is the wavelength 254nm.
The suitable temperature is 10℃ ~ 55℃, and the relative humidity is 45% ~ 60%.
Generally, a 30-watt ultraviolet lamp is installed in a room of 6-15m3, the height of which is not more than 1.5m from the operating table, the center of the vertical point between the lamp and the table is not more than 1.5m, the relative humidity is appropriate to 45-60%, the temperature should be in the range of 10-55 ° C, and the ultraviolet lamp must be kept dust-free and oil-free.
Application: surface, aseptic room air, distilled water;
Not suitable for: liquid medicine, solid material deep
3. Filtration and sterilization method
A method of removing living or dead microorganisms by filtration.
Suitable for sterilization of very heat-resistant liquid medicine.
Commonly used filters are G6 vertical melting glass funnel, 0.22μm microporous filter membrane and so on.
In order to ensure sterility, this method must be combined with aseptic operation and bacteriostatic agent;
The filter used and the container receiving the filtrate must be autoclaved at 121 ° C.
Fourth, gas sterilization
Gas sterilization uses gases formed by chemical disinfectants to kill microorganisms.
For example, ethylene oxide sterilization is a method of sterilization using ethylene oxide gas.
Ethylene oxide gas sterilization: Ethylene oxide induces cell death by alkylating proteins, DNA, and RNA, irreversibly preventing normal cell metabolism and replication.
It is suitable for sterilization of high risk articles or high risk articles that are not resistant to humidity and heat.
The above sterilization methods have their own characteristics and are suitable for different types of medical devices and occasions.
When selecting the sterilization method, it is necessary to consider the material, structure, use requirements and safety in the sterilization process of the medical device.