Thermal sterilization method
Thermal sterilization method uses high temperature to coagulate or denature bacterial proteins, inactivate enzymes, cause metabolic disorders, and cause bacterial death. Thermal sterilization methods include moist heat sterilization and dry heat sterilization. Moist heat can coagulate and deform bacterial proteins; dry heat can oxidize, denature, carbonize bacterial proteins, and cause electrolyte concentration to cause cell death. Thermal sterilization is convenient, effective, and non-toxic, and is the main sterilization method used by hospital disinfection supply centers. Pressure steam sterilization is the preferred sterilization method for moisture-resistant and heat-resistant medical devices.
Pressure steam sterilization uses moist heat sterilization. At the same temperature, moist heat has a better sterilization effect than dry heat for the following reasons:
1. The temperature required for protein coagulation is related to its water content. The higher the water content, the lower the temperature required for coagulation. During moist heat sterilization, bacterial proteins can absorb water, so they are easier to coagulate than in dry hot air at the same temperature.
2. During the wet heat sterilization process, steam releases a large amount of latent heat, further increasing the temperature. At the same temperature, wet heat sterilization takes less time than dry heat.
3. The penetration of wet heat gas is stronger than that of dry heat gas, so wet heat is more effective than dry heat. High-pressure steam can kill all microorganisms, even including bacterial spores, fungal spores and other high-temperature resistant individuals. The steam temperature of sterilization increases with the increase of steam pressure. By increasing the steam pressure, the sterilization time can be greatly shortened. Therefore, it is the most effective and widely used sterilization method.
Low temperature sterilization method
Low temperature sterilization method is a method of killing pathogenic microorganisms using chemical sterilizers. The temperature required for chemical agents to sterilize is relatively low, and it is usually called low temperature sterilization method or chemical sterilization method. The chemical disinfectant used in low temperature sterilization can kill all microorganisms and reach the sterilization guarantee level. Such chemical agents with sterilization effects include formaldehyde, glutaraldehyde, ethylene oxide, peracetic acid, etc. Chemical sterilization is used to sterilize instruments that cannot withstand high temperature and wet heat.
Commonly used low-temperature sterilization methods include hydrogen peroxide plasma low-temperature sterilization, ethylene oxide sterilization, low-temperature formaldehyde steam sterilization, etc.
1. Hydrogen peroxide plasma low-temperature sterilization
The items are sterilized by diffusing hydrogen peroxide liquid into a gas state, and the second stage of sterilization is carried out by the generated plasma. The plasma process can also accelerate and completely decompose the residue of hydrogen peroxide gas on the equipment and packaging materials. The characteristics of plasma sterilization are rapid action, reliable sterilization, low action temperature, clean and no toxic residue. It is suitable for endoscopes, heat-resistant equipment, various metal instruments, glass and other items; it can absorb moisture and gas.
2. Ethylene oxide sterilization
Ethylene oxide is a colorless gas with an odor similar to ether and is odorless at low concentrations. It has strong gas penetrating power and can penetrate cellophane, polyethylene or polyvinyl chloride films, etc., and produce non-specific alkylation effects on the proteins, DNA, and RNA of microorganisms, causing them to lose the basic reaction groups of metabolism and be killed. It has strong bactericidal power, a wide killing spectrum, reliable sterilization effect, and less damage to sterilized items.