19 18, the "flu" in Spain quickly spread to many countries, with a total death toll of 20 million, more than three times that of the First World War.
There are many reasons for human illness, but as far as the pathological causes of infectious diseases are concerned, it is mainly determined by the "occurrence circle" composed of pathogenic microorganisms, transmission routes and human resistance.
As the root of infectious diseases, pathogenic bacteria can only cause infection if they are highly toxic and abundant. In the ever-changing living environment, there are billions and billions of germs attacking you every day, so what do you rely on to protect yourself? If sound skin is the first line of defense to stop the invasion of various pathogens, then there are some peripheral defense lines outside the skin, which can annihilate some pathogens. Experiments show that a tear added with 2000 grams of water can still kill at least one kind of bacteria. Because tears contain lysozyme, it has a strong antibacterial effect. In addition, saliva and mucus on the nasal cavity are effective defense lines for the human body.
Humans have lived in a world full of microorganisms for thousands of years, and only by learning to adapt can they survive. However, human beings are not doomed not to get sick. Under normal circumstances, the body's defense structure can effectively prevent the invasion of germs. If the body's disease resistance is poor, people will have to turn to various drugs for help.
1929, British bacteriologist Fleming accidentally discovered penicillin while studying and cultivating staphylococci, which was the birth of the first antibiotic drug in human history. This pale yellow powder once created a miracle in World War II. In the hospital in Seoul, a central American city, the rescued wounded not only have to endure the pain of gunshot wounds and burns, but also fight to the death with pathogens invading the wounds. At that time, the only effective drug against germs was sulfonamides, but it was powerless in the face of some cunning and vicious pathogens. Facing thousands of dying patients, it is urgent to develop a more effective new drug. At that time, a young American doctor, Li Anshi, dissolved the pale yellow powder of penicillin discovered by Fleming in physiological saline and injected it drop by drop into the veins of 19 soldiers who had tried their best to treat the ineffective and dying soldiers. Results 12 people were pulled back from the brink of death and recovered completely. Then, he treated 49 fracture patients whose wounds had been infected with germs and constantly oozing foul pus, and 42 of them had a healing effect again.
So, how do antibiotics defeat pathogens? Because antibiotics are substances produced by microorganisms in the process of life activities, these substances have the ability to inhibit and kill microorganisms or tumor cells. Therefore, it is different from general physical and chemical disinfectants or fungicides. It disturbs and destroys various enzyme systems of pathogenic bacteria through biochemical reactions, which makes the metabolism of bacteria out of balance and achieves the effects of bacteriostasis and sterilization. Different antibiotics have different methods and effects.
Antibiotics such as penicillin and cephalosporin can inhibit the formation of bacterial cell walls. Antibiotics such as streptomycin, chloramphenicol, tetracycline, kanamycin, gentamicin and erythromycin can interfere with the synthesis of protein in pathogenic microorganisms.
With the increasing use of antibiotics, the scope of use is expanding day by day, which often gives people an illusion that no matter what disease they have, they always feel that it is better to eat more antibiotics. This is obviously very wrong. Because in most cases, the role of antibiotics is only to inhibit or weaken the activities of pathogenic bacteria, and people ultimately have to rely on the body itself to completely defeat pathogenic bacteria. Long-term use of an antibiotic can not only fail to play its due role, on the contrary, it will also cause pathogenic bacteria to produce "drug-resistant" mutant varieties, thus making the antibiotic lose its unique utility.
Recently, scientists all over the world re-studied antibiotics and found that "humans and bacteria have started a competition again." The past is actually a game in which leaders are constantly changing. With the outbreak of World War II, penicillin was widely used. Five years later, doctors found staphylococci that were not easily decomposed by penicillin. Of course, clever medical scientists invented new antibiotics to make bacteria "surrender" again. In this repeated "competition", drugs have maintained a weak leading position on the whole, and bacterial infectious diseases such as tuberculosis, bacterial pneumonia, septicemia, syphilis and gonorrhea have been slowly conquered. But this is still a long way from the medical community's announcement of a successful withdrawal. Now it is found that each pathogen has several variants, which can be resistant to more than one of 100 antibiotics, and some bacteria are resistant to all other drugs except one. At present, tuberculosis caused by drug-resistant tuberculosis accounts for17 of new cases, and 5% of them will die. Several drug-resistant pneumonia strains that appeared in South Africa in 1970s have spread to Europe and are appearing in the United States. At present, many patients often prescribe several antibiotics because one antibiotic is ineffective, which also brings a heavy economic burden.
Bacteria are really smart. When a group of bacteria were injected with a certain dose of penicillin, most of them died. But unexpectedly, some lucky bacteria carry mutant genes, which may protect them from drugs. They survived and passed on their drug resistance genes to their offspring. As mentioned earlier, a bacterium can leave about10.60 billion offspring within 24 hours, and then more effectively harm drug-resistant humans in the population. The latest research shows that these bacteria with mutants are also willing to share these mutant drug resistance genes with other different microbial bacteria. It attracts another kind of bacteria by oozing an attractive chemical. When they touch, they each open a hole and exchange a plasmid genetic material called DNA. This is the most terrible thing for mankind. For example, cholera bacteria can obtain tetracycline resistance from the most common and abundant Escherichia coli in human intestine. Therefore, the spread speed of bacterial drug resistance genes exceeded people's expectations. Faced with bacteria that compete with humans, scientists are studying various strategies. For example, drug-resistant bacteria produce genes that affect their viability, making it more difficult to tolerate temperature and acidity, and making drug-resistant bacteria always at a disadvantage in competition with similar bacteria, thus effectively inhibiting the spread of drug-resistant bacteria.