There are many kinds of chemical disinfectants, and people always choose an ideal chemical disinfectant to use in disinfection practice. As an ideal chemical disinfectant, it should have the following characteristics: (1) broad bactericidal spectrum; (2) Low effective concentration; (3) high sterilization speed; (4) stable performance; (5) Soluble in water; (6) It can be used at low temperature; (7) Not easily influenced by various physical and chemical factors; (8) Non-corrosive to articles; (9) odorless, tasteless and colorless; (10) low toxicity, no residual toxicity after disinfection; (1 1) is safe to use and not easy to burn; (12) low price; (13) Convenient transportation; (14) can be supplied in mass production. None of the current chemical disinfectants can fully meet the above requirements. Therefore, in use, we can only choose a disinfectant according to the nature of the sterilized goods, the needs of work and the performance of chemical disinfectants.

1 glutaraldehyde

Glutaraldehyde is an efficient disinfectant, which has the characteristics of broad spectrum, high efficiency, low toxicity, little corrosion to metals, little influence by organic matter and good stability. Suitable for disinfection and sterilization of medical instruments and precision instruments resistant to damp and heat. Its bactericidal concentration is 2%, and there are two kinds of glutaraldehyde in the market: 2% alkaline glutaraldehyde and 2% fortified acidic glutaraldehyde. Alkaline glutaraldehyde is usually used for sterilization of medical devices. Before use, a proper amount of sodium bicarbonate should be added, shaken evenly, left standing for 65438 0 hours, and the pH value should be determined. When the PH value is 7.5-8.5, glutaraldehyde has the strongest bactericidal effect. The sterilization of glutaraldehyde is the function of its monomer. When the pH value of the solution reaches 6, these monomers tend to polymerize. With the increase of pH value, this polymerization reaction is extremely rapid, precipitation can appear in the solution, and the polymer will lose its bactericidal effect after formation. Therefore, alkaline glutaraldehyde is a relatively unstable disinfectant, and 2% fortified acidic glutaraldehyde is fortified with polyoxyethylene fatty alcohol ether, which can enhance the bactericidal effect of glutaraldehyde. Its pH value is lower than 5, and its killing effect on bacterial spores is weaker than that of alkaline glutaraldehyde, but its killing effect on virus is stronger than that of alkaline glutaraldehyde, and its stability is better than that of alkaline glutaraldehyde. It can be used continuously for 28 days.

(1) sterilization principle: aldehyde disinfectants mainly rely on aldehyde groups to kill microorganisms. These drugs mainly act on hydrophobic groups, hydroxyl groups, carboxyl groups and amino groups of bacterial protein, which can alkylate them, cause protein to coagulate and cause bacterial death.

(2) Main advantages and disadvantages:

Advantages:

① Glutaraldehyde is a broad-spectrum and efficient disinfectant, which can kill all microorganisms;

② It can be used for sterilization of heat-resistant medical instruments;

③ Glutaraldehyde has low irritation, low corrosiveness, safety and low toxicity at the use concentration;

④ Organic matter has little influence, and 20% organic matter has little influence on sterilization effect.

Disadvantages:

(1) The sterilization time is long, generally reaching 10 hour;

② Glutaraldehyde is toxic and can cause bronchitis and pulmonary edema;

③ Sterilized medical devices should be fully rinsed with distilled water before use.

(3) bactericidal action

Alkaline glutaraldehyde is a broad-spectrum and efficient disinfectant, which can effectively kill various microorganisms, so it can be used as a disinfectant, but the effect of strengthening acidic glutaraldehyde to kill spores is slightly weak (table 1).

Table 1.2% glutaraldehyde kills spores

(4) Application of glutaraldehyde

① Disinfection and sterilization of medical devices

2% glutaraldehyde (alkaline, acidic and neutral) can be used for disinfection and sterilization of various medical devices that are not afraid of humidity. At room temperature, the clean and dry instruments can be completely immersed in glutaraldehyde water solution, and the disinfection effect of 10 hour or more can be achieved in 30 minutes.

No matter which preparation is used, 0.5% sodium nitrite should be added as preservative first, but once the preservative is added, it can only be stored for 1 month, and alkaline glutaraldehyde can only be used continuously for 1-2 weeks.

② Disinfection and sterilization of endoscope

Glutaraldehyde is the first choice for endoscope disinfection. At present, endoscopes are widely used and varied, and the manufacturing accuracy has reached a new level, but the requirements for disinfection and sterilization are getting higher and higher. Many parts of modern endoscopes are not resistant to high temperature and are afraid of corrosion, so most endoscopes are disinfected or sterilized with glutaraldehyde. The correct operation procedure of glutaraldehyde disinfection or sterilization is as follows: firstly, the contaminated items are treated harmlessly (the endoscope can be cleaned directly), the endoscope can be cleaned with 0.2% effective chlorine cleaning disinfectant, and then carefully scrubbed with neutral or enzyme-containing detergent; Rinse: rinse the detergent with clear water; Drying, after washing, the equipment needs to be dried; Sterilization: completely soak the dried instrument in 2% glutaraldehyde solution for a specified time, and then rinse the residual glutaraldehyde with sterile distilled water for later use or dry preservation. Table 2 lists the requirements of glutaraldehyde disinfection endoscopy abroad.

(5) Usage:

Sterilization: There is only one soaking method.

Immerse the cleaned and dried articles to be sterilized in 2% glutaraldehyde solution, cover them, soak them for 65438±00h, take them out after aseptic operation, rinse them with sterile water, and dry them after aseptic operation. Use alkaline glutaraldehyde 14 days.

Disinfection treatment: soaking method.

Soak the disinfected articles in 2% glutaraldehyde solution and cover them. Generally, it is contaminated by bacterial propagules, soaked for 10min, and soaked for 30min by hepatitis virus pollution. After taking out, rinse with sterile distilled water and air dry.

Wipe method: wipe the surface contaminated by bacterial propagules for 65438±00min and the surface contaminated by hepatitis virus for 30min with 2% glutaraldehyde solution.

(6) Precautions:

①2% acidic glutaraldehyde is corrosive to metals; 2% neutral glutaraldehyde is corrosive to carbon steel products such as surgical blades, and 0.5% sodium nitrite should be added to prevent rust before use.

② The sterilization effect of glutaraldehyde is greatly influenced by pH. When soaking medical devices with acidic or enhanced acidic glutaraldehyde, the pH should be adjusted to 7.5-8.8 with 0.3% sodium bicarbonate first. When the pH value exceeds 9.0, glutaraldehyde rapidly polymerizes and loses its bactericidal ability.

③2% alkaline glutaraldehyde can only be stored at room temperature for 2 weeks, and other preparations can be stored for 4 weeks.

(4) Glutaraldehyde is irritating to skin mucosa, so gloves should be worn when contacting the solution to prevent it from splashing into eyes or being inhaled into the body.

⑤ Distilled water should be used to prepare glutaraldehyde, and the container of glutaraldehyde solution should be clean.

⑥ Instruments disinfected or sterilized with glutaraldehyde must be fully cleaned with sterilized distilled water before use.

2 peracetic acid

Peroxyacetic acid, also known as peracetic acid, is a prominent disinfectant among all chemical disinfectants at present. It is an efficient disinfectant with a commercial concentration of 16-20%.

(1) sterilization principle: the sterilization principle of peracetic acid has two points:

(1) depending on strong oxidation, the enzyme loses its activity, leading to the death of microorganisms;

(2) Destroy microorganisms by changing the pH value in cells.

(2) Main advantages and disadvantages:

Advantages:

(1) has high efficiency and broad spectrum, can kill all microorganisms, and has reliable sterilization effect;

② Sterilization is rapid and thorough;

③ It can be used for low-temperature disinfection;

④ Low toxicity, no residual toxicity to sterilized articles, and the decomposition products are harmless to human body;

⑤ The synthesis process is simple, the price is low, and it is convenient for popularization and application.

Disadvantages:

① Volatile, unstable, easily decomposed during storage, and quickly decomposed when it meets organic matter, strong alkali, metal ions or heating;

② When the high concentration is stable but the concentration exceeds 45%, violent oscillation or heating can cause explosion;

③ Corrosion and bleaching;

④ It has a strong sour taste, which obviously irritates the skin and mucous membrane.

(3) Scope of application:

Suitable for disinfection and sterilization of corrosion-resistant articles, environment, skin, etc.

(4) Method of use

① soaking method

Put the disinfected or sterilized articles into peracetic acid solution and cover it.

Bacterial propagules were soaked in 0. 1%( 1000mg/L) for 15 minutes.

Hepatitis virus and mycobacterium tuberculosis: soak in 0.5%( 1500mg/L) for 30min.

Bacterial spores: disinfected with 1%( 10000mg/L) for 5min and sterilized for 30min.

Medical supplies or equipment should be cleaned and dried with sterile distilled water before use.

(2) Friction test method:

Used for large items, the usage is the same as soaking method.

③ Spraying method:

Disinfect the commonly contaminated surface and spray 0.2-0.4% (2000-4000mg/L) for 30-60min.

Spray 0.5%(5000 mg/L) peracetic acid for 30-60 minutes.

(5) Dosage of peracetic acid for disinfection (Table 3).

(6) Precautions for use

It should be stored in a ventilated and cool place.

Preparation of diluent before use:

The effective content should be determined before use, and the disinfectant should be prepared according to the determination results. When preparing the solution, avoid mixing with alkali or organic matter. To prevent the damage of peracetic acid to sterilized articles. Metal products and fabrics should be washed with clear water in time after soaking and disinfection. Beware of splashing into eyes or skin mucosa. Once spilled, rinse it with clear water in time. When disinfecting articles contaminated by blood, pus, etc. It is necessary to extend the action time appropriately.

3. Chlorine disinfectant

All disinfectants that can dissolve in water and produce hypochlorous acid are collectively called chlorine-containing disinfectants. It is an ancient disinfectant, but it is still an excellent disinfectant. Effective chlorine in chlorine-containing disinfectants usually refers not to the content of chlorine, but to the oxidizing ability of disinfectants, which is equivalent to the oxidizing ability of chlorine.

Disinfectants are divided into organic chlorine with chloramine as the main component and inorganic chlorine with hypochlorous acid as the main component. The former is slow in sterilization, but stable in performance, while the latter is fast in sterilization, but unstable in performance.

Common dosage forms:

(1) liquid chlorine, the chlorine content is more than 99.5% (v/v);

② Bleaching powder: containing available chlorine 25% (w/w);

(3) bleaching powder essence: containing 80% available chlorine (w/w/w)；;

④ Two out of three, containing 56% available chlorine (w/w);

(5) sodium hypochlorite, containing available chlorine10% (w/w);

⑥ sodium dichloroisocyanurate, containing 60% available chlorine (w/w);

⑦ Trichloroisocyanuric acid, containing 85-90% (w/w) of available chlorine;

⑧ Trisodium phosphate chloride, containing available chlorine 2.6%(W/W).

(1) sterilization principle: there are three sterilization mechanisms of chlorine-containing disinfectants:

(1) Oxidation of hypochlorous acid: hypochlorous acid is a very small neutral molecule, which can spread to the surface of negatively charged bacteria and penetrate into the bacteria through the cell wall for oxidation, destroying the phosphate dehydrogenase of bacteria, making the sugar metabolism unbalanced and causing bacterial death;

(2) The role of new ecological oxygen, which is formed by the decomposition of hypochlorous acid, oxidizes the protein of bacteria;

(3) Chlorination. Chlorine combines with protein of cell membrane to form compounds of nitrogen and chlorine, which interferes with cell metabolism and eventually leads to bacterial death.

(2) Main advantages and disadvantages:

Advantages:

① broad bactericidal spectrum, rapid action and reliable bactericidal effect;

② Low toxicity;

③ Convenient use and low price.

Disadvantages:

(1) is unstable, and available chlorine is easily lost;

② Bleached fabric;

③ Corrosiveness;

④ It is easily influenced by organic matter, pH, etc.

(3) bactericidal action

Usually it can kill bacterial reproduction, viruses, fungal spores and bacterial spores.

(4) Method of use

Commonly used disinfection and sterilization methods include soaking, wiping, spraying and dry powder disinfection.

① Soaking method: put the articles to be disinfected or sterilized into a container filled with chlorine-containing disinfectant, and cover it. Disinfect the articles contaminated by bacterial propagules, and soak them in disinfectant containing 200mg/L effective chlorine for 10 minutes or more; Disinfect articles contaminated by hepatitis virus and mycobacterium tuberculosis, and soak them in disinfectant containing 2000mg/L effective chlorine for more than 30 minutes; Disinfect the articles contaminated by bacterial spores and soak them in disinfectant containing 2000mg/L effective chlorine for 30 minutes.

(2) Wipe method: large items or other items that cannot be disinfected by soaking method shall be disinfected by wipe method. See the soaking method for the concentration and action time of disinfection drugs.

(3) Spraying method: evenly spray 1000mg/L disinfectant (wall surface: 200ml/m2；; ; Cement ground: 350mL/m2, land surface, 1000mL/m2), and the action lasts for more than 30min; In order to disinfect the surface contaminated by hepatitis virus and Mycobacterium tuberculosis, uniformly spray disinfectant containing available chlorine 2000mg/L (the spraying amount is the same as before) for more than 60 minutes.

④ Dry powder disinfection method: disinfect the excrement, add chlorine-containing disinfectants such as bleaching powder to the excrement according to the dosage of15, stir slightly and act for 2-6 hours to disinfect the hospital sewage. According to the dosage of 50 mg/L available chlorine, dry powder is added to the sewage, stirred evenly, and discharged after 2 hours.

(5) Factors affecting sterilization

① The general law of concentration and action time is that the higher the drug concentration, the longer the action time and the better the sterilization effect. However, when the concentration of bleaching powder and three-in-one drug increases, the pH value of its solution also increases, and sometimes it is necessary to extend the action time before sterilization.

② The lower the pH value, the stronger the bactericidal effect. The bactericidal effect of chlorine-containing disinfectants mainly depends on the concentration of undecomposed hypochlorous acid in the solution. The lower the pH value of the solution, the more undecomposed hypochlorous acid there is. With the increase of pH value, more and more hypochlorous acid is decomposed into hydrogen and hypochlorous acid ions, thus losing its bactericidal effect.

③ The increase of temperature can strengthen the sterilization effect. However, the sodium hypochlorite solution cannot be heated, otherwise it will decompose and reduce the sterilization effect;

(4) The existence of organic matter can consume available chlorine and affect its sterilization effect. It has obvious influence on low concentration disinfectant. Starch, fat and alcohol have little effect (methanol has synergistic effect on sodium hypochlorite), and organic matter has little effect on sodium dichloroisocyanurate;

⑤ Reducing substances such as thiosulfate, ferrous salt, sulfide and amino-containing compounds can also reduce its bactericidal effect. Attention should be paid to disinfection of sewage;

⑥ The hardness of water is less than 400mg/L, which has little effect on its bactericidal action.

(6) Precautions for use

(1) should be stored in a covered container and replaced in time;

② Not used for disinfection and sterilization of surgical instruments;

(3) Don't bring too much water when soaking for disinfection;

④ Do not use it to disinfect the surface contaminated by blood, pus, feces and other organic substances. Before disinfection, the organic matter attached to the surface should be removed;

⑤ Do not use for sterilization of surgical suture;

⑥ When disinfecting textiles with chlorine-containing disinfectants, rinse them with clear water immediately after disinfection.