The new coronavirus is raging, in this severe situation of the war "epidemic", although wearing masks and washing hands frequently is effective for controlling and preventing the new coronavirus infection, in the absence of vaccines and specific therapeutic drugs, disinfection is an important technical means to block the spread of the virus.
Coronaviruses are a class of RNA viruses with envelopes, and when the envelope is destroyed by disinfectants, RNA is also very easily degraded. According to the "Diagnosis and Treatment Plan for Pneumonia Infected by Novel Coronavirus (Trial Fifth Edition)" issued by the National Health and Health Commission, the virus is sensitive to ultraviolet rays and heat, and lipid solvents such as 56 °C for 30 minutes, ether, 75% ethanol, chlorine-containing disinfectants, peracetic acid and chloroform can effectively inactivate the virus, and chlorhexidine cannot effectively inactivate the virus.
According to the killing ability of chemical disinfectants on microorganisms, disinfectants can be divided into three categories: efficient, medium-effective and inefficient.
A highly effective disinfectant is a disinfectant that kills all bacterial propagules (including mycobacteria), viruses, fungi and their spores, and bacterial spores.
A medium-potent disinfectant is a disinfectant that does not kill bacterial spores, but can kill bacterial propagules (including mycobacteria), fungi, and most viruses.
Inefficient disinfectants are those that kill bacterial propagules and cystic viruses, but do not kill bacterial spores, mycobacteria and cystic membrane viruses, as well as certain fungi.
First, the mechanism of sterilization and disinfection
1. Denature the protein
Phenols, alcohols, aldehydes and heavy metals can coagulate or denature proteins, inhibiting the growth and reproduction of viruses and dying.
2. Interfere with the enzyme system
Heavy metal salts can bind to the thiol (-SH) enzyme of microorganisms, reducing or disappearing their activity, thereby affecting the metabolism of pathogenic bacteria. Oxidants and halogens can also oxidize certain enzyme systems in microorganisms.
3. Increase the permeability of the plasma membrane
The cleaning agent can reduce the surface tension of the cell membrane of the pathogenic bacteria, increase the permeability of the cell membrane, and leak out of the substance in the bacteria, causing death.
Second, the classification of sterilization and disinfectants
1. Alcohol disinfectant
The bactericidal effect is medium level, mainly used for skin disinfection; commonly used are 75% ethanol, 60% n-propanol and 70% isopropanol.
2. Iodine disinfectant
It is a variety of preparations made of iodine as the main bactericidal ingredient. Generally speaking, it can be divided into:
(1) Traditional iodine preparations: iodine aqueous solution, iodine tincture (commonly known as iodine wine) and iodoglycerin.
(2) Iodophor:It is a stable complex of iodine and surfactants (carriers) and solubilizers. There are three categories of non-ionic, cationic and anionic types; among them, non-ionic iodine volts are the most widely used and safest iodine volts, mainly povidone iodine (PVP-I) and polyol ether iodine (NP-I); especially povidone iodine (PVP-I), Which has been included in the pharmacopoeias of China and the world.
Nonionic type: complexes formed by elemental iodine and nonionic surfactants, etc.: e.g. povidone iodine (PVP-I), polyol ether iodine (NP-I), polyvinyl alcohol iodine (PVA-I), polyethylene glycol iodine (PEG-I. The most widely used are PVP-I and NP-I.
Cationic type: elemental iodine and cationic surfactants, etc. formed complexes: for example: quaternary ammonium salt iodine
Anionic type: complexes formed by elemental iodine and anionic surfactants, etc.: for example: alkyl sulfonate iodine.
(3) Other complex types: iodic acid solution (hypnosis: iodine, sulfuric acid, phosphoric acid, surfactant) and so on
Features: medium-acting disinfectant, bactericidal effect is susceptible to organic matter, traditional iodine preparations and compound iodine preparations are corrosive to the equipment.
3. Aldehyde disinfectant
Microbial mechanism: mainly rely on the aldehyde group, the aldehyde group acts on the protein of the bacterium, making it alkylated, causing protein coagulation.
Advantages: good sterilization effect, high efficiency disinfectant, broad spectrum, high efficiency, low toxicity, small corrosiveness to metals, small influence on organic matter, good stability.
Disadvantages: The commonality of aldehyde sterilizers is that they are toxic. In particular, formaldehyde, after the expiration date of use, can not be degraded by itself, has residual toxicity, and long-term use pollutes people, livestock and the surrounding environment.
Commonly used aldehyde disinfectants: formaldehyde, glutaraldehyde, phthalaldehyde.
4. Peroxide disinfectant
Peroxide disinfectants have always been the mainstream in the field of disinfection, oxidation type, through strong oxidation to destroy the bacterial cell structure, or oxidize some active groups in the cell structure and play a bactericidal role. Fatal structural changes occur in proteins, enzymes, and nucleic acids; protein synthesis is blocked; and cellular respiratory enzyme activity is lost.
The main ones are: peracetic acid, hydrogen peroxide, chlorine dioxide, hydrogen peroxide, peroxyglutaric acid, ozone.
Advantages: easily soluble in water, wide spectrum of sterilization, strong bactericidal force, fast sterilization, and can be completely degraded, decomposed to produce non-toxic components, no residual toxicity.
Disadvantages: unstable nature, transportation, storage has the risk of explosion; easy to decompose, corrosive. Irritating or toxic before decomposition, bleaching or corrosive effect on the article.
5. Chlorine-containing disinfectant
Refers to a disinfectant that can produce hypochlorous acid with bactericidal activity in water.
(1) Organic chlorine-containing disinfectants: such as sodium dichloroisocyanurate, bis (three) chloroisocyanuric acid, chloramine-T, dichlorodimethylhydantoin, tetrachlorogylurea chloride and other disinfectants.
(2) Inorganic chlorine-containing disinfectants: bleach powder (CaOCl2), bleach (white) powder (high efficiency calcium hypochlorite Ca(ClO)2·2H2O), sodium hypochlorite (NaClO·5H2O), trisodium chloride phosphate (Na3PO4·1/4NaOCl·12H2O), etc.
Advantages: strong sterilization ability.
Defects and hazards: corrosive and irritating, metabolites: chloroform is highly carcinogenic, the vast majority of irritation is strong, no surfactant effect.
6. Biguanide and quaternary ammonium salt disinfectant
It is a cationic surfactant disinfectant, mainly including: chlorhexidine (chlorhexidine) and other diguanide disinfectants, benzalkonium bromide (also known as neogel or brombenzyl ammonium bromide, that is, dodecyl dimethylbenzylammonium bromide), dumifen (also known as disinfection, that is, dodecyl dimethylethylene ethyl ammonium bromide) double-chain quaternary ammonium disinfectant, 100 poison (50% didecyl dimethyl ammonium bromide), new Jieling disinfectant (brominated bis (dodecyldimethyl) ethylenediammonium), tetradeclammonium salt (byejie).
Advantages: rapid sterilization, special effect on bacterial propagules.
Disadvantages: The vast majority are inefficient disinfectants, the disinfection effect is very poor in the presence of organic contaminants, and it is ineffective against non-capsular viruses (bursal sac, adenovirus, foot-and-mouth disease).
7. Compound chemical disinfectant
There are two main types of compound chemical disinfectant compatibility (compatibility principle)
Disinfectants and disinfectants: two or more kinds of disinfectants compounding, such as quaternary ammonium salts and iodine compounding, glutaraldehyde and hydrogen peroxide compounding its bactericidal effect to achieve synergy and synergy, that is, 1 + 1>2.
Disinfectants and auxiliaries: a disinfectant is added with appropriate stabilizers and buffers, potent agents to improve the comprehensive properties of disinfectants, such as stability, corrosiveness, sterilization effect, etc., that is, 1 + 0>1.
