When I heard about the pneumonia epidemic caused by the new coronavirus, a friend asked me how to treat this disease? Is it necessary to use a lot of antibiotics?
Actually, antibiotics are not needed to treat virus-induced pneumonia, because antibiotics are drugs that target bacterial infections and are not effective against viral infections.
In fact, although they are all pathogens, bacteria and viruses that may make people sick, they are very different in terms of pathogenicity and treatment methods.
Although they are small, bacteria are often much larger than viruses
Virus and bacteria are words we often hear, but they differ a lot.
First, they differ in size.
Bacterial individuals are often large, and we can easily observe them through ordinary light microscopes. In contrast, the virus will appear “petite”, we need to use an electron microscope with a magnification of more than 10,000 times to unveil its veil.
The ordinary optical microscope on the left and the electron microscope on the right
(Image source: Veer Gallery)
Second, their cell structures are also very different. Bacteria are simple organisms composed of single cells or multiple cells, and have cell walls. Viruses do not have this cellular structure.
Typical bacterial structure
(Image source: Human Education Edition junior high school biology textbook)
The structure of the virus is relatively simple, mainly the protein shell encapsulates genetic material.
The above picture shows two typical structures of viruses: the virus on the left has no envelope and the envelope on the right
Secondly, Bacteria can be divided into autotrophic bacteria and heterotrophic bacteria. Autotrophic bacteria can survive independently and are widely distributed in soil and water. Viruses can only rely on the living cells of other organisms. survive.
However, heterotrophic bacteria in bacteria include saprophytes and parasites. Saprophytes are bacteria that draw nutrients from dead animals and plants or other organic matter to maintain their normal life. Parasitic bacteria are similar to viruses. The parasitic bacteria are parasitic in living organisms, and are provided by the organism with nutrients and places, such as typhoid and dysentery bacillus, but most of the bacteria do not enter the cell like viruses, only parasite outside the cell.
It is also important to pay attention to the differences in their metabolic methods. Bacteria have many different metabolic methods. Viruses do not have their own metabolic system. They can only choose to rely on the host’s metabolism through parasitic methods. System for metabolism.
The “means” for bacteria to enter the body are much richer than viruses
As we all know, human beings are surrounded by various microorganisms, and all areas covered by the naked eye may be the gathering place of various viruses and bacteria. We have been living in such an environment for a long time, but the probability of illness is not as a result. The increase is because everyone has their own protection guardian- Immune system .
Picture Source: Veer Gallery
Skin and mucous membranes are the first line of defense of the human body. If the human body is free of skin damage and is not bitten by mosquitoes, the virus cannot enter the body through the skin. At this time, the cunning virus can only be exposed through the respiratory tract and eyes. The mucous membrane in the state enters the human body.
New coronavirus
(picture from Sogou Encyclopedia)
So in the face of this new type of coronavirus that has passed through the respiratory tract infection, you will know that wearing a scientific mask can prevent the virus from contacting the respiratory tract with a high probability, thereby protecting us from virus infection.
But for the bacteria, although the skin is also the first barrier to prevent it from entering the human body, there are still many special cases.
Vibrio cholerae causing cholera can enter the body through polluted water sources
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(Image source: Interactive Encyclopedia)
Some bacteria , such as Brucella, can break the “skin” barrier and infect the human body may eventually lead to serious consequences such as abortion and infertility ; And some pathogens , thanSuch as Mycobacterium tuberculosis, it will adhere to the dust in the air, With our breathing every moment and then smoothly enter our respiratory tract ; some bacteria will choose to enter the body through the digestive tract For example, when our water source is polluted, bacteria will grow in the water, and after we drink these polluted water sources, bacteria will enter the body with it.
It’s so cunning!
After the virus enters the human body, it needs to enter the cells if it wants to infect the human body
In general, there are several common ways for viruses to enter cells: injection invasion , which is more common in phage invasion; intracellular endocytosis , which is common in animals Virus invasion; Membrane fusion , mostly invasion by enveloped viruses. The invasion method of the new coronavirus is endocytosis. After the new coronavirus enters the human body, the outer spike protein can bind to specific receptors on the surface of human respiratory epithelial cells, and finally pass through the cell. The endocytosis enters the cell.
At this moment, you may want to ask, how do bacteria enter cells? In fact, most bacteria live outside cells, and they cannot infect host cells.
When the virus enters the cell, the “working mode” is turned on. The virus will use the energy and materials in the cell to replicate and produce more viruses, and eventually secrete them out of the cell through the Golgi apparatus inside the cell, completing the “mission” to make new progeny viruses.
By comparison, bacteria reproduce more autonomously and simply.
Cultivate bacteria and provide nutrients. The above picture is a petri dish full of bacteria.
But to grow the virus, you must seed it on live cells.
(Image source: http://www.bio-review.com/)
Bacteria generally reproduce asexually through dichotomy, and individual bacteria have other reproduction methods.
When a bacterium divides, it is also necessary to replicate genetic material, but if it is an autotrophic bacterium, it does not need to rely on external forces like a virus, and when it is separated into two daughter cells, it will not be produced like animal and plant cells. Membrane body, but the cell membrane and cell wall in the middle of the cell are trapped from the outside to the inside and become two cells.
Different ways, viruses and bacteria infect people differently
The reason why the virus can make people sick has a lot to do with the body’s own immune system.
When the virus invades the human body, the body’s own immune system will respond. When the virus is eliminated, a series of inflammatory reactions will occur. If the inflammatory response is too strong, it will cause some of the body’s own cells to be damaged, which will release a large amount of cell contents. The excessive content in the body will cause the immune system to further work. This positive feedback phenomenon will eventually It can cause the human body to collapse and even cause death in severe cases.
Take pneumonia caused by a new coronavirus as an example. It is precisely because this strong immune response occurs in the human lungs that a large number of immune cells flood into the lungs to participate in the immune response, which causes a series of inflammatory reactions and blood vessels. Increased permeability leads to symptoms such as fever, dry cough, and fatigue in the human body, and produces diseases such as rapid respiratory distress syndrome and coagulopathy, which eventually leads to lung failure and poses a great threat to our health.
(Image source: Veer Gallery)
However, only part of the virus can infect people. The virus has its own specific host, such as tobacco mosaic virus and phage. These viruses do not have specific pathogenicity to the human body, so they can get along with people in peace.
Compared to the terrible new coronavirus, the bacteria will look slightly cute, because most bacteria are harmless to humans, animals and plants, and even beneficial. Only a few bacteria we call pathogenic bacteria will The human body causes damage, and the pathogenicity of this pathogen depends on two factors: invasiveness and toxins .
Invasion refers to the ability of pathogenic bacteria to break through the body’s defense barrier, invade the host’s living tissues, grow and reproduce in the host, and spread to the surroundings. Toxins are powerful special toxic substances produced by certain pathogenic microorganisms. They can greatly enhance the toxic effects of pathogenic bacteria.
Bacterial toxins can be divided into exotoxin and endotoxin according to their sources, properties, and effects. Exotoxins have selective toxic effects on tissue cells, do not cause fever, but inhibit protein synthesis There are cytotoxicity, neurotoxicity, disturbance of water and salt metabolism, strong toxicity, and a small amount can kill experimental animals; while endotoxin is relatively weak, it can cause fever, diffuse intravascular coagulation, and granulocytopenia.
The pathogenic bacteria that make us smell so bad can cause extremely serious consequences because they have a strong invasive force and can produce extremely toxic toxins during growth and after death and rupture. .
There is such a big difference between viruses and bacteria, so what’s the difference between a viral infection and a bacterial infection?
Although both viral and bacterial infections may cause fever, cough, and other symptoms, bacterial infections of purulent secretions are more common, such as purulent nose, purulent phlegm, etc. Purulent discharge. Secondly, the symptoms of bacterial infections will be significantly improved after using antibiotics. But for viral infections, antibiotics have little effect. Usually we need to use laboratory indicators to determine what kind of infection.
JianDue to the difference between viral infection and bacterial infection, our treatment also needs to adopt different schemes to achieve the right remedy. Viral infections need to use different antiviral drugs according to the location of the viral infection. At the same time, we must pay attention to stimulate and improve autoimmunity. For bacterial infections, antibiotics are more commonly used. For different bacteria, different antibiotics are used.
As pathogens, viruses and bacteria still have similarities
As pathogens, viruses and bacteria are transmitted in basically the same way. There are two types of common transmission methods: horizontal transmission and vertical transmission .
Horizontal transmission refers to the transmission of viruses and bacteria between different individuals in a population, mainly respiratory or digestive tract transmission, direct contact and sexual contact transmission, insect-borne transmission and transmission through blood transfusion injection, etc.;
Vertical transmission is the method of transmission from the parent to the offspring directly through the placenta or birth canal.
The new type of coronavirus is mainly transmitted through droplets and contact . Generally speaking, the virus-infected people carry sneezing, coughing, droplets emitted during the speaking process, and exhaled air. If there is a virus, other people may be infected if they are in close contact with the infected person. It should also be noted that in a closed and airless situation, droplets with the virus will contaminate the surface of the object. Contacting these contaminated areas without timely cleaning and disinfection, and then touching the mucous membranes of the mouth, nose, and eyes with your hands at this time will also cause infection.
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Hand washing is very important (Image source: Veer Gallery)
Write here, I believe everyone should have understood why the new crownVirus-induced pneumonia cannot be treated with antibiotics. Although the epidemic situation has improved, we still need to continue to strengthen protection and reduce outings. Let us look forward to the end of the epidemic!
(Images from the source in this article have been authorized)
This article comes from WeChat public account: China Science Popularization Expo (ID: kepubolan) author: Liu Xin Yuan, Publisher: science China, Producer: computer network information Center, Chinese Academy of Sciences