(1) physical disinfection method
1. Mechanical disinfection
Generally, washing with soap and tap water can destroy most or even all bacteria on the hands, and using multi-layer masks can prevent bacteria from being discharged or invaded from the respiratory tract. Using the filter of ventilation device can isolate the air in operating room, laboratory and ward, and protect the aseptic state.
2. Thermal disinfection
Including fire, boiling, flowing steam, high heat steam, dry heat sterilization, etc. It can coagulate and denature the pathogen protein and lose its normal metabolic function.
(1) fire
This method can be used for pollutants, metal utensils and corpses with less economic value. Simple, economical and stable.
(2) boiling
This method is used for cooking-resistant articles and general metal utensils. Disinfection can be completed in 100℃ and 1 ~ 2 minutes, but it takes a long time for spores. It takes 30 minutes for anthrax spores to boil, 3 hours for tetanus spores and 6 hours for botulinum spores. When metal instruments are disinfected, alkaline agents such as 1 ~ 2% sodium carbonate or 0.5% soft soap can dissolve fat and enhance sterilization. 1% soapy water 15l/kg for cotton fabric has the efficacy of disinfection and decontamination. When the articles are boiled and disinfected, they shall not exceed 3/4 of the volume and shall be submerged under water. Pay attention to leaving gaps to facilitate convection.
(3) flowing steam disinfection
The relative humidity is 80 ~ 100%, and the temperature is near 100℃. The surface of the object is condensed by water vapor to release heat energy, killing pathogens. When negative pressure is generated by steam condensation and contraction, external hot steam is promoted to enter the tonic and penetrate into the depth of the article, which accelerates heating and promotes disinfection.
(4) high-pressure steam sterilization
Usually, the pressure is 98.066kPa and the temperature is 12 1 ~ 126℃ and 15 ~ 20 minutes, which can completely kill bacterial spores. Suitable for heat-resistant and moisture-proof articles.
(5) dry heat sterilization
Dry and hot air has poor conduction, small heat capacity, weak penetration and slow heating of objects. Sterilization takes 160 ~ 170℃, 1 ~ 2 hours. Suitable for glass containers and metal utensils that can't hold water. The heat resistance of different pathogens is expressed by thermal death time.
3. Radiation disinfection
There are two kinds of non-ionizing radiation and ionizing radiation. The former includes ultraviolet rays, infrared rays and microwaves, while the latter includes high-energy electron beams (cathode rays) of C rays. Infrared rays and microwaves mainly rely on heat to sterilize.
Ionizing radiation equipment is expensive, which is harmful to both objects and human body, so it is used less. At present, ultraviolet rays are widely used, which can cause changes in cell components, especially nucleic acids, protoplasmic proteins and acids, and lead to microbial death. The wavelength range of ultraviolet rays is 2 100~3280A ~ 3280a, the wavelength of killing microorganisms is 2000~3000A, and the strongest effect is 2500~2650A. With a few exceptions, fungal spores are the strongest, followed by bacterial spores, and bacterial propagules are the weakest. Ultraviolet penetration is poor, and ordinary glass with a thickness of 2 mm cannot penetrate below 3000A A. Dust and relative humidity in the air will reduce its sterilization effect. The permeability of water decreases with depth and turbidity. However, due to its convenient use and no damage to drugs, it is widely used for surface disinfection of air and general items. Irradiated human body can cause skin erythema, ultraviolet ophthalmia and ozone poisoning. Therefore, people should avoid or take corresponding protective measures when using it.
Sunlight also depends on ultraviolet rays, but only 39% can reach the ground due to scattering and absorption in the atmosphere, so it is only suitable for microorganisms with low endurance and long exposure. In addition, in addition to laboratory applications, air filtration can be used in buildings with only ventilation, so general disinfection work is difficult to apply.
(2) Chemical disinfection method
According to the effect of protein on pathogens, it can be divided into the following categories.
1. coagulin disinfectants include phenols, acids and alcohols.
(1) phenols
There are mainly phenol, lysol and hexachlorophenol. It has a special smell and limited bactericidal ability. It can change the color of textiles, make rubber products brittle and have certain irritation to the skin, so it is rarely used except Lisu people. Phenol (carbolic acid): colorless crystal with special smell, pink when wet, but its disinfection power is not reduced. It is a cytoplasmic toxin. At 20℃ for 30 minutes, it can kill the bacterial reproductive1:80 ~1:10 solution, but it can't kill spores and viruses with strong resistance. Soap can saponify fat, dissolve protein, promote its penetration, and enhance disinfection effect, but it is toxic, irritating to the skin, and stinks, so it cannot be used for skin disinfection. Lysol: made of 47.5% cresol and potassium soap. Reddish brown, soluble in water, has decontamination effect, and its bactericidal power is 2-5 times stronger than that of carbolic acid. Generally, it is 2 ~ 5% aqueous solution, which can be used for spraying, wiping, soaking containers, washing hands, etc. Bacterial reproductive type 10 ~ 15 minutes can be killed, but the effect on spores is poor. BHC: It is a bisphenol compound, slightly soluble in water and easily soluble in alcohol, ester and ether. Adding alkali or soap can promote dissolution, with less toxicity and irritation, but stronger bactericidal power. Mainly used for skin disinfection. Washing hands with 2.5 ~ 3% hexachlorophenol soap can reduce skin bacteria by 80 ~ 90%. It is reported that it can cause nerve damage and is suitable for long-term use.
(2) acid
It can kill bacterial propagules and spores. However, it is easy to damage articles and is generally not used for indoor disinfection. 5% hydrochloric acid can sterilize washing utensils and fruits, 15% salt can sterilize fur and leather in 2.5% solution, and 10l/kg can be heated at 30℃ for 40 hours. Lactic acid is often used for air disinfection. Steaming with 10g lactic acid in 100m3 space for 30 minutes can kill staphylococci and influenza virus.
(3) alcohol ethanol (alcohol)
75% concentration can quickly kill the bacterial reproductive type, but it has a slow effect on general viruses, and it is uncertain about hepatitis viruses. It has a certain killing effect on fungal spores and has no effect on spores. Used for skin disinfection and thermometer soaking disinfection. Because it can't kill spores, it can't be used for soaking disinfection of surgical instruments. Isopropanol can kill more than 2 bacteria. Dissolved protein disinfectant.
Mainly alkaline drugs, such as sodium hydroxide, lime and so on.
(1) sodium chloride
White crystal, easily soluble in water, strong bactericidal power, 2 ~ 4% solution can kill virus and bacterial reproduction, 10% solution can kill mycobacterium tuberculosis, and 30% solution can kill spores within 10 minutes. Because of its strong corrosiveness, it is rarely used and is only used to kill anthrax spores.
(2) Lime
When it meets water, it will generate high temperature, dissolve protein and kill pathogens. Commonly used 10 ~ 20% lime milk to disinfect excreta, the dosage must be twice that of excreta, and it will act for 4 ~ 5 hours after stirring. 20% lime milk is used for disinfection of anthrax contaminated places, sprayed once every 4 ~ 6 hours and continuously for 2 ~ 3 times. Brushing the wall twice can kill mycobacterium tuberculosis. Because of its unstable nature, it should be freshly prepared when used.
3. Oxidized protein disinfectant
Include chlorine-containing disinfectants and peroxide disinfectants. Because of its strong disinfection effect, it is widely used in medical and epidemic prevention work at present.
(1) bleaching powder
The most widely used. The main component is calcium hypochlorite [Ca(OCl)2], with an effective content of 25-30%, which is unstable in nature and can be decomposed by light, heat, humidity and CO2. Therefore, it should be sealed and stored in a dry place away from light for no more than 1 year. Hypochloric acid is an effective component, which can penetrate into cells, oxidize sulfur and hydrogen genes of cellular enzymes and destroy cytoplasmic metabolism. Strong and rapid sterilization in acidic environment, high concentration can kill spores, powder is used for disinfection of feces, sputum and pus. Add 200 grams of dry powder per liter, stir evenly, place 1 ~ 2 lobules, add 5 grams of dry powder per liter of urine, and let stand for 10 minute. 10 ~ 20% emulsion can be used for spraying toilets and polluting vehicles. If it is stored for a long time, the actual available chlorine content should be measured and the dosage should be revised. The powder and tablet of bleaching powder concentrate can contain 60 ~ 70% available chlorine, and can be reduced in proportion when used.
(2) chloramine -t
It is an organic chlorine disinfectant, containing 24 ~ 26% available chlorine, and its performance is relatively stable. After sealing 1 year, only 0. 1% of available chlorine is lost. Slightly soluble in water (12%), less irritating and corrosive, slower than hypochlorous acid. 0.2% 1 hour can kill bacterial propagule, 5%2 hours can kill mycobacterium tuberculosis, and it takes more than 10 hour to kill spores. Various ammonium salts can promote its bactericidal effect. 1 ~ 2.5% solution also has effect on hepatitis virus. The active liquid must be prepared within 1 ~ 2 hours, and the sterilization effect will be reduced if the time is too long.
(3) sodium dichloroisocyanurate
It is also famous for chlorine, which is a widely used organic chlorine disinfectant with a chlorine content of 60 ~ 64.5%. It has the advantages of high efficiency, broad spectrum, stability, high solubility and low toxicity. Aqueous solution can be used for spraying, soaking and soaking, or dry powder can be used to directly disinfect pollutants and treat excrement such as feces, and the usage is the same as bleaching powder. Directly sprayed on the ground, the dosage is 10 ~ 20g/m2. Mixed with paraformaldehyde dry powder and ignited, the gas can be fumigated and disinfected, and can be mixed with coagulant No.92 (based on aluminum hydroxide, synthesized with iron powder, sulfuric acid, hydrogen peroxide, etc.). ) is changed into "clean when it meets water" at the ratio of 1: 4, which is used for disinfection of drinking water. It can also be mixed with sodium sulfonate to prepare various disinfection and cleaning liquids, such as Dijingmei and Youchlorojing. It can kill hepatitis virus. In addition, trisodium phosphate chloride and chlorobromodicyandiamide also have the same effect.
(4) peracetic acid
Also known as peracetic acid, it is a colorless and transparent liquid, volatile, and pungent sour. It is a quick-acting disinfectant with the same effect, easily soluble in organic solvents such as water and ethanol, with bleaching and corrosion effects, volatile and pungent sour. It is an efficient quick-acting disinfectant, easily soluble in organic solvents such as water and ethanol, with bleaching and corrosion effects, unstable properties, and easy to decompose when exposed to heat, organic matter, heavy metal ions and strong alkali. 0.0 1 ~ 0.5%, 0.5 ~ 10 minutes can kill bacterial propagules, and 1%5 minutes can kill spores. The common concentration is 0.5 ~ 2%, which can be disinfected by soaking, spraying and wiping, and the aerosol (5% concentration, 2.5 ml) can be carried out under closed conditions.
(5) Chlorine peroxide
3 ~ 6% solution, 10 minutes can be disinfected. /10 ~ 25% 60% for 60 minutes, which can be used to sterilize heat-resistant plastic products, tableware, clothes, etc. 10% hydrogen peroxide deep spraying glue to disinfect indoor polluted surface; 180 ~ 200ml/m3 can kill bacterial propagules within 30 minutes; 400ml/m3, 60 minutes can kill spores.
Ethanol, absorbed by the lungs, will cause anesthesia, but it is harmless to the skin and can be used instead of ethanol.
(6) Potassium permanganate
Soaking in the concentration of 1 ~ 5% for 15 minutes can kill bacterial propagules, and is often used for disinfection of utensils and melons.
4. Cationic surfactants
There are mainly quaternary ammonium salts, high concentration of coagulation protein and low concentration of inhibition of bacterial metabolism. It has the advantages of high bactericidal concentration, low toxicity and irritation, no bleaching, no corrosion, no odor, stability and good water solubility. However, the bactericidal power is not strong, especially spores, which are greatly influenced by organic substances and have many compatibility taboos. There are bromogeramine, Disinfection Ning (Dumi Cang) and Disinfection Net produced in China. Among them, Disinfection Ning has strong bactericidal power, and the commonly used concentration is 0.5 ~ 1.0 ‰, which can be used to disinfect skin, metal instruments and tableware. Not suitable for disinfection of excreta and secretion.
5. Alkylation disinfectant
(1) formalin
It is a 34 ~ 40% formaldehyde solution with strong bactericidal effect. 1 ~ 3% solution can kill bacterial reproduction and 5% solution can kill spores for 90 minutes. Indoor fumigation generally uses 20ml/m3, the same amount of water 10 hour, and it takes 80ml/m324 hours to eliminate spore pollution. Suitable for heat-resistant articles such as fur, man-made fiber and silk fabric. Because of its poor penetration and great irritation, the disinfection items should be spread out and the house should be sealed.
(2) Glutaraldehyde
It acts like formaldehyde. It is stable in acidic solution, but its bactericidal effect is poor. It can last for 2 weeks in alkaline solution, but it can greatly improve the sterilization effect. Therefore, 0.3% sodium bicarbonate is usually added to 2% valeraldehyde to correct the pH value for compounding (the bactericidal effect is enhanced and the stability can be maintained 18 months. Non-corrosive, with the advantages of broad spectrum, quick action, high fever and low toxicity, it can be widely used to kill bacteria, spores and viruses. Not suitable for disinfection of skin and mucosa.
(3) Ethylene oxide
It is a colorless liquid at low temperature and its boiling point is 10.8℃, so it is a gas sterilization agent at normal temperature. Its function is to destroy the protein decomposition of microorganisms through alkylation. The general application rate is 0.4 ~ 0.7 kg/m2, 15℃, 12 ~ 48 hours. When the temperature increases 10℃, the bactericidal power can be increased by more than 1 times, and the bactericidal effect is the best when the relative humidity is 30%. It has the advantages of high activity, strong permeability, no damage to articles and no residual poison, and can be used for disinfection of paper, books, cloth, fur, plastics, artificial fibers and metal products. Because of its strong penetrating power, it needs to be disinfected in a closed container. Avoid open flames to prevent explosion. Ventilation after disinfection to prevent inhalation.
6. Others
(1) iodine
Through halogenation, it interferes with protein metabolism. The effect is quick and lasting, non-toxic and less affected by organic matter. There are often sulfur wine and sulfur volt (sulfur and surfactant are amorphous combinations). Commonly used for disinfection of skin and mucosa and emergency treatment of medical devices.
(2) Chlorhexidine
It is a biguanide compound. It has a strong disinfection effect on bacteria. Can be used for disinfection of hands, skin, medical equipment, clothes, etc. The common concentration is 0.2 ~ 1 ‰.