We all know that alcohol can kill bacteria. How is alcohol disinfected?

It means that pathogenic microorganisms have lost their infectivity. Another common concept is "sterilization", that is, killing pathogenic microorganisms and making them lose their biological activity. It can be seen that sterilization is more thorough than disinfection, and about 75% alcohol can play a good role in sterilization.

The general structure of bacteria generally includes cell wall, cell membrane, cytoplasm and genetic material from outside to inside. Let's look at the effects of alcohol on these structures.

If it is a virus, alcohol will kill it faster, because the outermost layer of the virus is protein, and alcohol can destroy this structure more quickly and directly.

Alcohol can kill bacteria, because an appropriate concentration of alcohol can penetrate the cell wall of bacteria, dissolve the cell membrane, and directly drive into the cytoplasm to destroy protein, an important life substance.

The higher the alcohol concentration, the stronger the cohesion of protein. 95% alcohol can quickly solidify protein wrapped on the surface of bacteria, forming a protective film to prevent alcohol from entering bacteria, so it can't completely kill bacteria. If the alcohol concentration is lower than 70%, it can enter bacteria, but it can't coagulate protein in the body, killing bacteria completely. Studies have proved that only 75% alcohol can enter bacteria smoothly, and can effectively coagulate protein in bacteria and kill bacteria.

Alcohol is a medium disinfectant, which can kill bacterial propagules, Mycobacterium tuberculosis, most fungi and viruses, but it can't kill bacterial spores or inactivate hepatitis B virus in a short time.

Alcohol is the most common disinfectant in our life. Different concentrations of alcohol have different effects. Most of the liquor we drink every day has an alcohol concentration of 40%-60%. Medically, 75% alcohol is used for sterilization; 50% alcohol is used to prevent bedsores and cool patients with fever.

By the way, it is not easy to buy in many pharmacies in the United States, but benzalkonium chloride is used instead. The purpose, you know, is to prevent hungry drunks from buying wine.

I used to think that the higher the alcohol concentration, the stronger the bactericidal effect. In fact, this is a wrong understanding. Because of the high alcohol concentration, the protein dehydration of bacteria is too fast, which makes the protein on the surface of bacteria denature and solidify, forming a solid envelope. On the contrary, alcohol can't penetrate bacteria well, which affects their bactericidal ability. 75% alcohol is similar to the osmotic pressure of bacteria, which can gradually penetrate into the interior of bacteria before protein denaturation on the surface of bacteria, dehydrate, denature and solidify all protein of bacteria, and finally kill bacteria. However, when the alcohol concentration is lower than 75%, the bactericidal ability is correspondingly reduced due to the decrease of permeability.