How and why antibiotic resistance is generated

How and why antibiotic resistance is generated
How and why antibiotic resistance is generated

  • They call it the silent pandemic: “More and more people are dying because no antibiotic is capable of killing the bacteria that cause the infection.”


  • Bruno González Zorn, WHO adviser: “All bacteria are becoming resistant to the antibiotics with which they are treated”


  • Every year 1.2 million people die in the world for this reason: “We are facing one of the most important health problems facing humanity”

Carlos has taken many antibiotics in his life. Maybe too many. So many that now they no longer work, when you catch a bacterial infection. Is this what we are talking about when we talk about antibiotic resistance? No, is not that. Or not only. “It is a global problem that stems from individual problems”Explain Raúl Rivas, Professor of Microbiology at the University of Salamanca. Antibiotic resistance is a good example of how “the little things we do can have a global impact”, assures. And what are those little things?

We talk about “improper or indiscriminate use of antibiotics”which encourages that, many times, They are not effective against certain bacteria. Or against none. Something that is happening more and more, in all parts of the world. “We are facing one of the most important health problems facing humanity. Our well-being and all of modern medicine depend on antibiotics working,” he warns. Bruno González Zorn, Professor of Microbiology at the Complutense University of Madrid and WHO adviser in Antibiotic Resistance and One Health.

In fact, this problem is already called the “silent pandemic”. It is the next one we’re going to have to face. Which we are already facing. “All surgeries and all transplants, for example, are in danger, because the antibiotics that we have available work less and less. More and more people are dying because no antibiotic is capable of killing the bacteria that cause the infection.”warns González Zorn. We are talking about 1.27 million deaths a year, directly attributable to this problem. And growing.

Misuse of antibiotics “accelerates the problem”

Rivas puts some Examples of such misuse of antibiotics. They sure sound close. “When you have an infection and they give you an antibiotic for seven days, but the third, as you are already well, you leave it “. The situation is very common. What happens then?

“That antibiotic, what it does is attack the bacteria constantly, every so often”, that is, it keeps it at bay. “It prevents the appearance of cells that can accommodate to this situation and the appearance of resistance.” But if I stop taking it, the bacteria “gets used to it, it finds a way to avoid it, to resist, and we started to have a problem.”

Another example. “I have a virus, a cold… and I decide, on my own, to take an antibiotic. No no no. Antibiotics do not work for viruses”, Rivas insists. “Again, what I do is encourage the emergence of resistance.”

But our misuse of antibiotics is not the only cause of the emergence of resistant bacteria. There is more. “The misuse of antibiotics is accelerating the problem” of bacterial resistance. But How and why do bacteria become resistant?

Bacteria, antibiotics and natural selection

“What bacteria that are multiresistant to antibiotics are doing is fighting to survive. This It’s an arms warRivas explains. A war in which “some have weapons and others shields. We use chemical molecules to attack bacteria: antibiotics. And they use shields to defend themselves.”

How do they defend themselves? They evolve, they change, they adapt.… For example, they produce molecules that are capable of cutting the structure of the antibiotic and make it not work”. Bacteria “are taking out new shields against our weapons”. But it is that, in addition, they know our weapons perfectly. Because they used them long before us. “Antibiotics existed long before we discovered them,” Rivas warns.

The Microorganisms produce antimicrobial substances, including antibiotics. “They used them to fight between thems, to be able to dominate the territory, or eliminate the adversary, or fight for space or nutrients…”, explains Rivas. “When we discovered them (at the beginning of the 20th century), they were already using them.” The first antibiotic to be discovered, penicillin, is produced by a fungus. Then came streptomycin, which is produced by a bacterium. “That a group of bacteria, in fact, streptomyces, are the major producers of antibiotics”.

Rivas puts another example that can be commonplace: clavulanic acid, for example, used in augmentin. This commonly used antibiotic combines amoxicillin and clavulanic acid. “Amoxicillin is a derivative of penicillin, and clavulanic acid is produced by streptomyces.”

As these bacteria already naturally produce these antibiotics, they also naturally generate resistance to these substances. That is, “even if we did not use antibiotics, that would happen.” But not so much. It wouldn’t be a problem. Because now, he warns, “this process is accelerating” due to the use we make of them. Rather, for misuse. Go back to augmentin, for example, and think how many times you may have used it. And if they have used it well.

“Our use subjects them to selective pressure, only the bacteria that best resist this substance will survive,” Rivas explains. It is pure natural selection. And what is happening after a century using antibiotics, abusing them, is that there are many bacteria that have become resistant. Six are especially worrying, but they are becoming more and more, as this study recently published in The Lancet warns.

It is a problem that is growing. The spread of these bacteria will continue to expand. Those that best resist are the ones that will prevail and proliferate more and more, and in addition, others that are acquiring resistance will continue to increase ”, warns Rivas.

They all become resistant, and more and more are “pan-resistant”

Gonzalez Zorn, who has been working on this issue for decades, goes further. Ensures that the problem affects all bacteriaeven some as common as gonorrhea or tuberculosis. “They are all becoming resistant to the antibiotics they are treated with. It is a problem that affects all bacteria.”

He also points out that “there are not only multi-resistant bacteria (that resist many antibiotics), but also we have more and more pan-resistant bacterianamely, bacteria that are resistant to all antibiotics available in clinical practice. And we have these in almost all of our hospitals,” warns the expert. Years ago, he explains, we only found them in a hospital in India or China, but They have already reached Europe and “they are invading hospitals.”

González Zorn comments on a situation that may also sound familiar to you. When a person enters a hospital with pneumonia and soon after, dies. Many times – you will have heard it – it is said that the infection complicated him and he died. In many cases, what is behind it is this resistance to antibiotics: a bacterium against which there were no weapons available. “Cast It is happening more and more in Spanish hospitals”warns the UCM scientist.

“If you have an infection with this type of bacteria, it will be much more difficult to cure yourself. They can give you an antibiotic, but it won’t work. And if there is no possible treatment, that It can lead to death in many cases. It is something that is already happening”, explains Raúl Rivas.

“That is why we call it a silent pandemic, because there are many deaths a year about which very little is said,” warns González Zorn. It is estimated that 4,000 people die in Spain every year for this reason. “Are four times more deaths than traffic accidentsbut we don’t hear about all those people who die in hospitals because antibiotics have not worked for them”, laments González Zorn.

Use and abuse of antibiotics in animals

The The causes of this problem, therefore, are several. From the natural resistance generated by the bacteria themselves, to the one we generate due to our abuse and misuse of antibiotics. But there is something else: the abuse and misuse that is being made of antibiotics in animals.

In Spain and in Europe, in general, this is very controlled”, points out Rivas, but “we are talking about a global issue” and what happens in other parts of the world ends up affecting all of us. Is he “One Health” concept, that has been repeated so much throughout the pandemic.

He warns that this, “combined with the direct contact between natural bacterial communities and resistant bacteria are driving bacterial evolution and the appearance of more resistant strains”.

Doctors and veterinarians must work together: the One Health strategy

Hence it is It is important to attack the problem from several sides. Not only from human health, but also from animal health. And with that, we return to the One Health perspective. “We must educate all prescribers (of antibiotics) well: doctors and veterinarians”warns González Zorn. And above all, work together.

“Because It is useless for us to control antibiotics in hospitals if they continue to be used, by the ton, without control in animals. And backwards”. González Zorn knows what he is talking about. Twenty years ago, he created the UCM Antibiotic Resistance Unit, which he currently directs. “The flagship of the One Health concept in the world has been resistance to antibiotics.”

Both he and Rivas warn that the problem is accelerating and that the forecasts in this regard may fall short. It is estimated that for By 2050, bacterial infections will be the leading cause of death globally, being able to reach 10 million deaths per year. “But it is a forecast that was made in 2014,” warns González Zorn. “We think it will be sooner, even in 2040.”

Rivas remembers that, at the beginning of the 20th century, the highest mortality was due to infectious diseases, but that changed radically with the advent of antibiotics, among other things. “Today, the infectious diseases are no longer on the podium, but If this continues like this, we can return to the starting square”.


The article is in Spanish

Tags: antibiotic resistance generated

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