Features of the use of antibacterial drugs in obstetric practice. The problem of antibiotic resistance

The decrease in the effectiveness of antibiotic therapy for purulent infection is due to drug resistance of microorganisms. Antibiotic resistance of microorganisms is due to: 1) the duration of the course of antibiotic therapy; 2) irrational, without proper indications, use of antibiotics; 3) use of the drug in small doses; 4) short-term course of antibiotic therapy. Of considerable importance in increasing the resistance of microorganisms to antibiotics is the uncontrolled use of antibiotics by patients, especially tablet drugs.

Simultaneously with the increase in antibiotic resistance, the microbial landscape is changing. The main causative agents of purulent surgical infection were staphylococci, Escherichia coli, and Proteus. Microbial associations began to occur frequently. When treating purulent processes caused by associations of microorganisms, the use of antibiotics is now a difficult task, since if one of the association strains is resistant to the antibiotics used, then during treatment microorganisms sensitive to them will be suppressed, and resistant strains will actively multiply.

It has been established that the rate of development and severity of antibiotic resistance depend both on the type of antibiotic and on the microorganisms. Therefore, before antibiotic therapy, it is necessary to determine the sensitivity of microorganisms to antibiotics.

Currently, the most common method for determining the sensitivity of microbial flora to antibiotics is the method paper disks. This method, as the simplest, is used by most practical laboratories. Assessment of the degree of sensitivity of microbial flora to antibiotics is carried out in areas of growth inhibition in accordance with the instructions for determining the sensitivity of microbes to antibiotics, approved by the Committee on Antibiotics in 1955.

However, this method has a very serious drawback - it usually takes 2-3 days, or even more days, before the sensitivity of the microorganism to the antibiotic becomes known. This means that the time to start using antibiotic therapy will be missed. That is why in clinical practice they are persistently looking for ways to early determine the sensitivity of microorganisms to antibiotics. However, to date, such a method has not yet been developed. True, A.B. Chernomyrdik (1980) proposed an indicative method for quickly prescribing antibiotics based on bacterioscopy of discharge from a purulent wound. In this case, Gram-stained smears are examined under a microscope. According to a specially developed table, an antibacterial drug is selected according to the microorganism found in the preparation.

The fight against the adaptive ability of microorganisms to antibiotics, as well as against the antibiotic resistance of microorganism strains, is quite difficult and is carried out in three directions: 1) the use of large doses of antibiotics; 2) finding new antibacterial drugs, including antibiotics; 3) a combination of antibacterial drugs and antibiotics with different mechanisms of action on the microbial cell, as well as a combination of antibiotics with other drugs that have a specific effect on antibiotic resistance.

The use of large doses of antibiotics is not always possible due to the toxicity of some of them. In addition, the use of large doses of antibiotics is permissible only if the microorganism is sensitive to this antibiotic. In increased doses, but not more than 2-3 times higher than therapeutic doses, drugs that have minimal toxicity to the patient’s body can be used. At the same time, as evidenced by American scientists, the use of high doses of antibiotics does not prevent the formation of antibiotic-resistant forms of microorganisms.

In our country, the fight against antibiotic resistance of microorganisms is aimed at creating new antibacterial drugs, including antibiotics. In addition, more rational ways of administering antibiotics are being developed to create high concentrations in the patient’s body.

Antibiotic resistance of microorganisms can be overcome by combined administration of antibiotics. In this case, it is necessary to take into account the nature of their interaction - it is unacceptable to use a combination of antibiotics that mutually destroy each other’s activity (antagonism of antibiotics). Knowledge of the possibility of interaction between antibiotics makes it possible to increase the effectiveness of antibacterial therapy, avoid complications and reduce the manifestation of the adaptive properties of microorganisms.

According to historical sources, many thousands of years ago, our ancestors, faced with diseases caused by microorganisms, fought them with available means. Over time, humanity began to understand why certain medicines used since ancient times can affect certain diseases, and learned to invent new medicines. Now the volume of funds used to combat pathogenic microorganisms has reached an especially large scale, compared even to the recent past. Let's look at how throughout history people, sometimes without knowing it, used antibiotics, and how, as knowledge accumulates, they use them now.

A special project about humanity’s fight against pathogenic bacteria, the emergence of antibiotic resistance and a new era in antimicrobial therapy.

The sponsor of the special project is the developer of new highly effective binary antimicrobial drugs.

Bacteria appeared on our planet, according to various estimates, approximately 3.5–4 billion years ago, long before eukaryotes. Bacteria, like all living beings, interacted with each other, competed and fought. We cannot say for sure whether they were already using antibiotics to defeat other prokaryotes in the battle for a better environment or nutrients. But there is evidence of genes encoding resistance to beta-lactams, tetracyclines and glycopeptide antibiotics in the DNA of bacteria that were present in the 30,000-year-old ancient permafrost.

A little less than a hundred years have passed since the moment that is considered to be the official discovery of antibiotics, but the problem of creating new antimicrobial drugs and using already known ones in the face of rapidly emerging resistance to them has been troubling humanity for the last fifty years. It is not without reason that in his Nobel speech, the discoverer of penicillin, Alexander Fleming, warned that the use of antibiotics must be taken seriously.

Just as the moment of discovery of antibiotics by humanity is delayed by several billion years from their initial appearance in bacteria, so the history of human use of antibiotics began long before their official discovery. And we are not talking about Alexander Fleming’s predecessors who lived in the 19th century, but about very distant times.

Antibiotic use in ancient times

Even in Ancient Egypt, moldy bread was used to disinfect cuts (video 1). Bread with mold fungi was used for medicinal purposes in other countries and, apparently, in general in many ancient civilizations. For example, in Ancient Serbia, China and India, it was applied to wounds to prevent the development of infections. Apparently, the inhabitants of these countries, independently of each other, came to the conclusion about the healing properties of mold and used it to treat wounds and inflammatory processes on the skin. The ancient Egyptians applied crusts of moldy wheat bread to ulcers on the scalp and believed that using these remedies would help appease the spirits or gods responsible for disease and suffering.

Video 1. Causes of mold, its harm and benefits, as well as its use in medicine and prospects for future use

The inhabitants of Ancient Egypt used not only moldy bread to treat wounds, but also self-made ointments. There is information that around 1550 BC. they prepared a mixture of lard and honey, which they applied to wounds and bandaged with a special cloth. Such ointments had some antibacterial effect, including due to the hydrogen peroxide contained in honey. The Egyptians were not pioneers in the use of honey - the first mention of its healing properties is considered to be an entry on a Sumerian tablet dating back to 2100-2000. BC, which states that honey can be used as a medicine and ointment. And Aristotle also noted that honey is good for treating wounds.

In the process of studying the bones of mummies of ancient Nubians who lived in the territory of modern Sudan, scientists discovered a high concentration of tetracycline in them. The mummies were approximately 2,500 years old, and it is likely that the high concentrations of the antibiotic in the bones could not have occurred by chance. Even in the remains of a four-year-old child, its quantity was very high. Scientists speculate that these Nubians had been consuming tetracycline for a long time. Most likely, its source was bacteria Streptomyces or other actinomycetes found in plant grains from which the ancient Nubians made beer.

People around the world have also used plants to fight infections. It is difficult to understand exactly when some of them began to be used due to the lack of written or other material evidence. Some plants were used because people learned about their anti-inflammatory properties through trial and error. Other plants were used in cooking, and along with their taste properties they also had an antimicrobial effect.

This is the case with onions and garlic. These plants have been used in cooking and medicine for a long time. The antimicrobial properties of garlic were known in China and India. And not so long ago, scientists found out that traditional medicine used garlic for a reason - its extracts depress Bacillus subtilis, Escherichia coli And Klebsiella pneumonia .

In Korea, since ancient times, Schisandra chinensis has been used to treat gastrointestinal infections caused by salmonella. Schisandra chinensis. Already today, after testing the effect of its extract on this bacterium, it turned out that Schisandra actually has an antibacterial effect. Or, for example, spices that are widely used around the world were tested for the presence of antibacterial substances. It turned out that oregano, cloves, rosemary, celery and sage inhibit pathogenic microorganisms such as Staphylococcus aureus, Pseudomonas fluorescens And Listeria innocua. On the territory of Eurasia, peoples often harvested berries and, naturally, used them, including in treatment. Scientific research has confirmed that some berries have antimicrobial activity. Phenols, especially ellagitannins, contained in cloudberries and raspberries, inhibit the growth of intestinal pathogens.

Bacteria as a weapon

Diseases caused by pathogenic microorganisms have been used since ancient times to cause harm to the enemy with minimal personal costs.

At first, Fleming's discovery was not used to treat patients and continued its life exclusively behind the doors of the laboratory. Moreover, as Fleming's contemporaries reported, he was not a good speaker and could not convince the public of the usefulness and importance of penicillin. The second birth of this antibiotic can be called its rediscovery by British scientists Ernst Chain and Howard Florey in 1940–1941.

The USSR also used penicillin, and while in Great Britain they used a strain that was not particularly productive, the Soviet microbiologist Zinaida Ermolyeva discovered it in 1942 and even managed to establish the production of the antibiotic during the war. The most active strain was Penicillium crustosum, and therefore at first the isolated antibiotic was called penicillin-crustosin. It was used on one of the fronts during the Great Patriotic War to prevent postoperative complications and treat wounds.

Zinaida Ermolyeva wrote a small brochure in which she talked about how penicillin-crustosin was discovered in the USSR and how the search for other antibiotics took place: “Biologically active substances”.

In Europe, penicillin was also used to treat the military, and after this antibiotic began to be used in medicine, it remained the exclusive privilege of the military. But after a fire on November 28, 1942 in a Boston nightclub, penicillin began to be used to treat civilian patients. All victims had burns of varying degrees of complexity, and at that time such patients often died from bacterial infections caused, for example, by staphylococci. Merck & Co. sent penicillin to the hospitals where victims of this fire were being held, and the success of the treatment brought penicillin into the public spotlight. By 1946 it had become widely used in clinical practice.

Penicillin remained available to the public until the mid-50s of the 20th century. Naturally, being in uncontrolled access, this antibiotic was often used inappropriately. There are even examples of patients who believed that penicillin was a miracle cure for all human diseases, and even used it to “treat” something that by nature was incapable of responding to it. But in 1946, one American hospital noticed that 14% of staphylococcus strains taken from sick patients were resistant to penicillin. And in the late 1940s, the same hospital reported that the percentage of resistant strains had risen to 59%. It is interesting to note that the first evidence that resistance to penicillin appeared in 1940 - even before the antibiotic began to be actively used.

Before the discovery of penicillin in 1928, there were, of course, discoveries of other antibiotics. At the turn of the 19th and 20th centuries, it was noticed that the blue pigment of bacteria Bacillus pyocyaneus capable of killing many pathogenic bacteria, such as Vibrio cholerae, staphylococci, streptococci, pneumococci. It was named pyocyonase, but the discovery did not serve as the basis for drug development because the substance was toxic and unstable.

The first commercially available antibiotic was the drug "Prontosil", which was developed by the German bacteriologist Gerhard Domagk in the 1930s. There is documentary evidence that the first person cured was his own daughter, who had long suffered from a disease caused by streptococci. As a result of treatment, she recovered in just a few days. Sulfonamide drugs, which include Prontosil, were widely used during the Second World War by the countries of the anti-Hitler coalition to prevent the development of infections.

Shortly after the discovery of penicillin, in 1943, Albert Schatz, a young employee in the laboratory of Selman Waksman, isolated it from a soil bacterium Streptomyces griseus a substance with antimicrobial activity. This antibiotic, called streptomycin, was active against many common infections of the time, including tuberculosis and plague.

And yet, until about the 1970s, no one thought seriously about the development of antibiotic resistance. Then two cases of gonorrhea and bacterial meningitis were seen, where a bacterium resistant to treatment with penicillin or penicillin antibiotics caused the death of the patient. These events marked the end of decades of successful disease treatment.

We must understand that bacteria are living systems, therefore they are changeable and over time are capable of developing resistance to any antibacterial drug (Fig. 2). For example, bacteria could not develop resistance to linezolid for 50 years, but still managed to adapt and live in its presence. The probability of developing antibiotic resistance in one generation of bacteria is 1:100 million. They adapt to the action of antibiotics in different ways. This could be a strengthening of the cell wall, which, for example, is used Burkholderia multivorans, which causes pneumonia in people with immunodeficiencies. Some bacteria such as Campylobacter jejuni, which causes enterocolitis, very effectively “pumps” antibiotics out of cells using specialized protein pumps, and therefore the antibiotic does not have time to act.

We have already written in more detail about the methods and mechanisms of adaptation of microorganisms to antibiotics: “ Evolution in a race, or why antibiotics stop working". And on the website of the online education project Coursera there is a useful course about antibiotic resistance Antimicrobial resistance - theory and methods. It describes in some detail about antibiotics, the mechanisms of resistance to them and the ways in which resistance spreads.

The first case of methicillin-resistant Staphylococcus aureus (MRSA) was recorded in the UK in 1961, and in the USA a little later, in 1968. We will talk about Staphylococcus aureus in a little more detail later, but in the context of the rate at which it develops resistance, it is worth noting that in 1958 the antibiotic vancomycin began to be used against this bacterium. He was able to work with strains that were resistant to methicillin. And until the end of the 1980s, it was believed that resistance to it should take longer to develop or not develop at all. However, in 1979 and 1983, after just a couple of decades, cases of resistance to vancomycin were also reported in different parts of the world.

A similar trend was observed for other bacteria, and some were able to develop resistance within a year. But some adapted a little slower, for example in the 1980s only 3–5% S. pneumonia were resistant to penicillin, and in 1998 - already 34%.

21st century - “crisis of innovation”

Over the past 20 years, many big pharmaceutical companies - such as Pfizer, Eli Lilly and Company and Bristol-Myers Squibb - have reduced the number of developments or even closed projects to create new antibiotics. This can be explained not only by the fact that it has become more difficult to find new substances (because everything that was easy to find has already been found), but also because there are other popular and more profitable areas, for example, the creation of drugs to treat cancer or depression.

However, from time to time, one or another team of scientists or a company announces that they have discovered a new antibiotic and declares that “it will definitely defeat all bacteria/some bacteria/a certain strain and save the world.” After this, nothing often happens, and such statements only cause skepticism among the public. Indeed, in addition to testing the antibiotic on bacteria in a Petri dish, it is necessary to test the alleged substance on animals, and then on humans. This takes a lot of time, is fraught with many pitfalls, and usually at one of these phases the discovery of a “miracle antibiotic” is replaced by a closure.

In order to find new antibiotics, various methods are used: both classical microbiology and newer ones - comparative genomics, molecular genetics, combinatorial chemistry, structural biology. Some suggest moving away from these “traditional” methods and turning to the knowledge accumulated throughout human history. For example, in one of the British Library books, scientists noticed a recipe for a balm for eye infections, and they wondered what it could do now. The recipe dates back to the 10th century, so the question is - will it work or not? - was really intriguing. The scientists took exactly the ingredients that were specified, mixed them in the right proportions, and tested them against methicillin-resistant Staphylococcus aureus (MRSA). To the surprise of the researchers, more than 90% of the bacteria were killed by this balm. But it is important to note that this effect was observed only when all ingredients were used together.

Indeed, sometimes antibiotics of natural origin work no worse than modern ones, but their composition is so complex and depends on many factors that it is difficult to be absolutely sure of any specific result. Also, it is impossible to say whether the rate of development of resistance to them is slowing down or not. Therefore, they are not recommended to be used as a replacement for primary therapy, but as an addition under the strict supervision of doctors.

Resistance problems - examples of diseases

It is impossible to give a complete picture of the resistance of microorganisms to antibiotics, because this topic is multifaceted and, despite the somewhat subsided interest on the part of pharmaceutical companies, is being actively researched. Accordingly, information is rapidly emerging about more and more cases of antibiotic resistance. Therefore, we will limit ourselves to just a few examples in order to at least superficially show the picture of what is happening (Fig. 3).

Tuberculosis: a risk in the modern world

Tuberculosis is especially common in Central Asia, Eastern Europe and Russia, and the tuberculosis germs ( Mycobacterium tuberculosis) resistance occurs not only to certain antibiotics, but also to their combinations, should cause alarm.

Due to reduced immunity, patients with HIV often experience opportunistic infections caused by microorganisms that can normally be present in the human body without harm. One of them is tuberculosis, which is also noted as the leading cause of death in HIV-positive patients around the world. The prevalence of tuberculosis by region of the world can be judged from statistics - patients with HIV who contract tuberculosis if they live in Eastern Europe have a 4 times higher risk of dying than if they lived in Western Europe or even Latin America. Of course, it is worth noting that this figure is influenced by the extent to which it is customary in the medical practice of the region to test patients for susceptibility to drugs. This allows antibiotics to be used only when necessary.

WHO is also monitoring the situation with tuberculosis. In 2017, it released a report on tuberculosis survival and monitoring in Europe. There is a WHO strategy to eliminate tuberculosis, and therefore close attention is paid to regions with a high risk of contracting this disease.

Tuberculosis claimed the lives of such past thinkers as the German writer Franz Kafka and the Norwegian mathematician N.H. Abel. However, this disease is alarming both today and when trying to look into the future. Therefore, both at the public and state levels it is worth listening to the WHO strategy and trying to reduce the risks of contracting tuberculosis.

The WHO report emphasizes that since 2000, fewer cases of tuberculosis infection have been recorded: between 2006 and 2015, the number of cases decreased by 5.4% per year, and in 2015 decreased by 3.3%. However, despite this trend, WHO calls for attention to the problem of antibiotic resistance Mycobacterium tuberculosis, and, using hygiene practices and constant monitoring of the population, reduce the number of infections.

Resistant gonorrhea

Extent of resistance in other bacteria

About 50 years ago, methicillin-resistant Staphylococcus aureus (MRSA) strains began to emerge. Infections caused by methicillin-resistant Staphylococcus aureus are associated with more deaths than infections caused by methicillin-sensitive Staphylococcus aureus (MSSA). Most MRSA is also resistant to other antibiotics. Currently, they are common in Europe, Asia, the Americas, and the Pacific region. These bacteria are more likely than others to become resistant to antibiotics and kill 12 thousand people per year in the United States. It's even a fact that in the United States, MRSA kills more people each year than HIV/AIDS, Parkinson's disease, emphysema, and homicide combined.

Between 2005 and 2011, fewer cases of MRSA as a hospital-acquired infection were reported. This is due to the fact that medical institutions have taken strict control over compliance with hygiene and sanitary standards. But in the general population, this trend, unfortunately, does not persist.

Enterococci resistant to the antibiotic vancomycin are a big problem. They are not as widespread on the planet compared to MRSA, but about 66 thousand cases of infection are recorded in the United States every year Enterococcus faecium and, less often, E. faecalis. They are the cause of a wide range of diseases and especially among patients in medical institutions, that is, they are the cause of hospital infections. When infected with enterococcus, about a third of cases occur with strains resistant to vancomycin.

Pneumococcus Streptococcus pneumoniae is the cause of bacterial pneumonia and meningitis. More often, the disease develops in people over 65 years of age. The emergence of resistance complicates treatment and ultimately leads to 1.2 million cases and 7 thousand deaths annually. Pneumococcus is resistant to amoxicillin and azithromycin. It has also developed resistance to less common antibiotics, and in 30% of cases it is resistant to one or more drugs used in treatment. It should be noted that even if there is a small level of resistance to an antibiotic, this does not reduce the effectiveness of treatment with it. The use of the drug becomes useless if the number of resistant bacteria exceeds a certain threshold. For community-acquired pneumococcal infections, this threshold is 20–30%. Recently, fewer cases of pneumococcal infection have begun to occur, because in 2010 they created a new version of the vaccine PCV13, which is effective against 13 strains S. pneumoniae.

Routes of spread of resistance

An approximate diagram is shown in Figure 4.

Close attention should be paid not only to bacteria that are already developing or have developed resistance, but also to those that have not yet acquired resistance. Because over time, they can change and begin to cause more complex forms of disease.

The attention to non-resistant bacteria can also be explained by the fact that, even if they are easily treatable, these bacteria play a role in the development of infections in immunocompromised patients - HIV-positive patients undergoing chemotherapy, premature and post-term newborns, in people after surgery and transplantation. And since a sufficient number of these cases occur -

• Around 120 thousand transplants were performed worldwide in 2014;
• in the USA alone, 650 thousand people undergo chemotherapy annually, but not everyone has the opportunity to use drugs to fight infections;
• in the USA, 1.1 million people are HIV-positive, in Russia - a little less, officially 1 million;

That is, there is a chance that over time, resistance will appear in those strains that do not yet cause concern.

Hospital-acquired, or nosocomial, infections are increasingly common nowadays. These are the infections that people become infected with in hospitals and other medical institutions during hospitalization and simply when visiting.

In the United States in 2011, more than 700 thousand diseases caused by bacteria of the genus Klebsiella. These are mainly nosocomial infections that lead to a fairly wide range of diseases, such as pneumonia, sepsis, and wound infections. As is the case with many other bacteria, since 2001, a massive emergence of antibiotic-resistant Klebsiella began.

In one of the scientific works, scientists set out to find out how antibiotic resistance genes are distributed among strains of the genus Klebsiella. They found that 15 fairly distant strains expressed metallo-beta-lactamase 1 (NDM-1), which is capable of degrading almost all beta-lactam antibiotics. These facts gain greater strength if we clarify that the data for these bacteria (1777 genomes) were obtained between 2011 and 2015 from patients who were in different hospitals with different Klebsiella infections.

The development of antibiotic resistance can occur if:

• the patient takes antibiotics without a doctor’s prescription;
• the patient does not follow the course of medication prescribed by the doctor;
• the doctor is not properly qualified;
• the patient neglects additional preventive measures (washing hands, washing food);
• the patient often visits medical institutions where there is an increased likelihood of becoming infected with pathogenic microorganisms;
• the patient undergoes planned and unscheduled procedures or operations, after which it is often necessary to take antibiotics to avoid the development of infections;
• the patient consumes meat products from regions that do not comply with standards for residual antibiotic content (for example, from Russia or China);
• the patient has reduced immunity due to illness (HIV, chemotherapy for cancer);
• the patient is undergoing a long course of antibiotic treatment, for example, for tuberculosis.

You can read about how patients independently reduce the dose of an antibiotic in the article “Adherence to taking medications and ways to increase it in case of bacterial infections.” Recently, British scientists expressed a rather controversial opinion that it is not necessary to undergo the entire course of treatment with antibiotics. American doctors, however, reacted to this opinion with great skepticism.

Present (impact on the economy) and future

The problem of bacterial resistance to antibiotics covers several areas of human life. First of all, this is, of course, the economy. According to various estimates, the amount that the government spends on treating one patient with an antibiotic-resistant infection ranges from $18,500 to $29,000. This figure is calculated for the United States, but perhaps it can be used as an average guideline for other countries to understand scale of the phenomenon. This amount is spent on one patient, but if you calculate it for everyone, it turns out that in total you need to add $20,000,000,000 to the total bill that the state spends on health care per year. And this is in addition to $35,000,000,000 in social spending. In 2006, 50,000 people died from the two most common hospital-acquired infections, sepsis and pneumonia. This cost the US healthcare system more than $8,000,000,000.

We have previously written about the current situation with antibiotic resistance and strategies to prevent it: “ Confrontation with resistant bacteria: our defeats, victories and plans for the future » .

If the first and second line antibiotics do not work, then you either have to increase the doses in the hope that they will work, or use the next line of antibiotics. In both cases, there is a high probability of increased toxicity of the drug and side effects. In addition, a higher dose or a new drug will likely cost more than the previous treatment. This affects the amount spent on treatment by the state and the patient himself. And also for the length of time the patient is in the hospital or on sick leave, the number of doctor visits and economic losses from the fact that the employee does not work. More days on sick leave are not empty words. Indeed, a patient with a disease caused by a resistant microorganism has to be treated for an average of 12.7 days, compared with 6.4 for the usual disease.

In addition to the reasons that directly affect the economy - spending on medicines, sick pay and time spent in the hospital - there are also slightly veiled ones. These are the reasons that affect the quality of life of people who have antibiotic-resistant infections. Some patients - schoolchildren or students - cannot fully attend classes, and therefore they may experience delays in the educational process and psychological demoralization. Patients who undergo courses of strong antibiotics may develop chronic diseases due to side effects. In addition to the patients themselves, the disease morally depresses their relatives and those around them, and some infections are so dangerous that the sick have to be kept in a separate room, where they often cannot communicate with loved ones. Also, the existence of hospital infections and the risk of contracting them do not allow you to relax while undergoing treatment. According to statistics, about 2 million Americans annually become infected with hospital-acquired infections, which ultimately claim 99 thousand lives. This most often occurs due to infection by microorganisms that are resistant to antibiotics. It is important to emphasize that in addition to the above-mentioned and undoubtedly important economic losses, people’s quality of life also suffers greatly.

Predictions for the future vary (video 2). Some pessimistically point out that by 2030–2040, cumulative financial losses will amount to $100 trillion, which equates to an average annual loss of $3 trillion. For comparison, the entire annual US budget is only 0.7 trillion higher than this figure. The number of deaths from diseases caused by resistant microorganisms, according to WHO estimates, will approach 11–14 million by 2030–2040 and will exceed deaths from cancer.

Video 2. Lecture by Marin McKenna at TED-2015 - What do we do when antibiotics don’t work any more?

The prospects for the use of antibiotics in animal feed are also disappointing (video 3). In a study published in the journal PNAS, estimated that more than 63,000 tons of antibiotics were added to feed worldwide in 2010. And this is only a conservative estimate. This figure is expected to increase by 67% by 2030, but most alarmingly, it will double in Brazil, India, China, South Africa and Russia. It is clear that since the volumes of added antibiotics increase, the cost of funds for them will also increase. There is an opinion that the purpose of adding them to feed is not at all to improve the health of animals, but to accelerate growth. This allows you to quickly raise animals, profit from sales, and raise new ones again. But with increasing antibiotic resistance, it will be necessary to add either larger volumes of antibiotics or create combinations of them. In any of these cases, the costs of these drugs for farmers and the state, which often subsidizes them, will increase. At the same time, sales of agricultural products may even decline due to animal mortality caused by the lack of an effective antibiotic or the side effects of a new one. And also because of fear on the part of the population, who do not want to consume products with this “enhanced” drug. A decrease in sales or an increase in the price of products can make farmers more dependent on subsidies from the state, which is interested in providing the population with essential products, which the farmer provides. Also, many agricultural producers, due to the above reasons, may find themselves on the verge of bankruptcy, and, consequently, this will lead to the fact that only large agricultural companies will remain on the market. And, as a result, a monopoly of large giant companies will arise. Such processes will negatively affect the socio-economic situation of any state.

Video 3. BBC talks about how dangerous the development of antibiotic resistance in farm animals can be

All over the world, areas of science related to determining the causes of genetic diseases and their treatment are actively developing; we are watching with interest what is happening with methods that will help humanity “get rid of harmful mutations and become healthy,” as fans of prenatal screening methods like to mention , CRISPR-Cas9 and the method of genetic modification of embryos that is just beginning to develop. But all this may be in vain if we are unable to resist diseases caused by resistant microorganisms. Developments are needed that will overcome the problem of resistance, otherwise the whole world will be in trouble.

Possible changes in people's everyday lives in the coming years:

• sale of antibiotics only by prescription (exclusively for the treatment of life-threatening diseases, and not for the prevention of common colds);
• rapid tests for the degree of microorganism resistance to antibiotics;
• treatment recommendations confirmed by a second opinion or artificial intelligence;
• remote diagnosis and treatment without visiting places where sick people gather (including places where medicines are sold);
• testing for the presence of antibiotic-resistant bacteria before surgery;
• prohibition of performing cosmetic procedures without proper testing;
• a reduction in meat consumption and an increase in its price due to the increased cost of farming without the usual antibiotics;
• increased mortality of people at risk;
• increase in mortality from tuberculosis in countries at risk (Russia, India, China);
• limited distribution of the latest generation of antibiotics around the world to slow down the development of resistance to them;
• discrimination in access to such antibiotics based on financial status and place of residence.

Conclusion

Less than a century has passed since the beginning of large-scale use of antibiotics. At the same time, it took us less than a century for the result to reach grandiose proportions. The threat of antibiotic resistance has reached a global level, and it would be foolish to deny that it is through our own efforts that we have created such an enemy for ourselves. Today, each of us feels the consequences of already emerging resistance and resistance in the process of developing when we receive from a doctor prescribed antibiotics that do not belong to the first line, but to the second or even last. Now there are options for solving this problem, but the problems themselves are no less. Our efforts to combat rapidly resistant bacteria are like a race. What will happen next - time will tell.

Nikolai Durmanov, ex-head of RUSADA, speaks about this problem in the lecture “Crisis of Medicine and Biological Threats”.

And time, indeed, puts everything in its place. Means are beginning to appear to improve the performance of existing antibiotics; scientific groups of scientists (scientists for now, but suddenly this trend will return to pharmaceutical companies) are working tirelessly to create and test new antibiotics. You can read about all this and perk up your spirit in the second article of the series.

Superbug Solutions is a sponsor of a special project on antibiotic resistance

Company Superbug Solutions UK Ltd. ("Superbug Solutions", UK) is one of the leading companies engaged in unique research and development of solutions in the field of creating highly effective binary antimicrobial drugs of a new generation. In June 2017, Superbug Solutions received a certificate from the largest research and innovation program in the history of the European Union, Horizon 2020, certifying that the company’s technologies and developments are breakthroughs in the history of the development of research to expand the use of antibiotics.

Antibiotic resistance is the resistance of some organism to compounds from the class of antibiotics. Currently, antibiotics are the only category of medications whose effectiveness is gradually decreasing. The very fact of antibiotic resistance is simply impossible to exclude - this is due to the progress of life, evolution at different stages and forms of organisms from the simplest to complex macrosystems.

Relevance of the issue

Antibiotic resistance of microorganisms is developed completely naturally. Initially, the level is low, gradually reaches medium values, and then develops to high stability. Microscopic organisms that show increased levels of resistance to one antimicrobial are likely to have protection against other compounds. The process of acquiring resistance cannot be reversed, but sensitivity can be slowly restored - albeit only partially.

Currently, antibiotic resistance is a global problem associated with insufficient infection control. Antimicrobial compounds are widely used in agriculture and the food industry. Substances similar to antimicrobial drugs are actively used in everyday life. All this affects the acquisition by pathological forms of life of an increased level of resistance to those substances that were previously deadly to them.

About the nuances of the phenomenon

Antibiotic resistance of bacteria can be natural, and it is possible to acquire resistance to antibiotics.

The formation and spread of the phenomenon is largely explained by the free sale of drugs from the antimicrobial class in pharmacies. According to the rules, these must be dispensed strictly according to a doctor’s prescription, but many outlets sell a number of products freely. Most often this applies to cases where the client is interested in purchasing gentamicin or ciprofloxacin.

One of the problems of modern medicine is the irrational use of antimicrobial drugs, which is also one of the mechanisms provoking the growth of antibiotic resistance. Often the prescription of funds is unjustified and even chaotic. Antibiotics are normally needed before surgery, but are often used after surgery. Prescribing unreasonably low dosages to a patient, lack of infection control, improper organization of the treatment process - all this provokes an increase in antibiotic resistance of pathological microorganisms.

About problems and realities

Although scientists are working nonstop to develop new drugs that are more effective and efficient, the use of antimicrobial agents has faced two major challenges in recent years. This is antibiotic resistance, already mentioned above, as well as the expansion of the diversity of dosage forms of pathogens. Antimicrobial resistance is now relevant for all types of microscopic life forms. This is the main reason why drug therapy is becoming less and less effective. In modern medicine, particular difficulties are created by the widespread distribution of antimicrobial-resistant Pseudomonas aeruginosa and Escherichia coli, Proteus and staphylococci.

As studies have shown, currently the problem of antibiotic resistance is becoming increasingly urgent: from half to 90% of all isolated strains are resistant to various compounds.

About the nuances of the problem

It has been established that the level of resistance to antimicrobial compounds is formed unevenly. This process occurs rather slowly with respect to penicillin drugs, cycloserine, polymyxin, and chloramphenicol. Against the backdrop of a slow decline in effectiveness, the therapeutic effect of the course weakens.

Regarding cephalosporins, tetracyclines, and aminoglycosides, scientists have found that antibiotic resistance also develops relatively slowly in microscopic life forms. Therapeutic efficacy decreases at a similar rate.

The problem of antibiotic resistance is most relevant when infected with strains from which rifampicin, linco- and oleandomycin, and fusidine should help. Resistance to these compounds can develop during the first course of treatment.

How does this happen?

The mechanisms of antibiotic resistance have long attracted the attention of scientists. If these processes could be brought under control, the problem of the persistence of pathological microorganisms would be solved. It has now been revealed that quite often the phenomenon is observed due to modification of the antimicrobial composition. The form will then become inactive. For example, this is possible if a microorganism generates some enzyme that enters into a chemical reaction with a medicinal compound.

A classic example: staphylococcus is capable of producing beta-lactamase. This substance affects the beta-lactam penicillin ring, opening it and making the drug safe for the pathogen.

Many Gram-negative life forms show increased resistance to aminoglycosides. This is explained by their ability to generate phosphorylating, acetylating compounds that destroy the molecule of the antimicrobial substance. Also, gram-negative pathogens can produce acetyltransferase, which deactivates chloramphenicol.

About mechanisms: continuing the topic

By studying the mechanisms of antibiotic resistance of microorganisms, scientists have found that reactions are possible during which the target is transformed, the effect of the antibiotic on which should have shown the desired result. Protein structures are inactivated, and a stable complex is formed. It was revealed that at the chromosomal level, resistance to aminoglycosides is explained by the transformation or removal of the protein structure on the 30S subunit of the bacterial chromosome, which normally represents a sensitivity receptor. Resistance to the penicillin series and cephalosporins is explained by the transformation of the penicillin-binding protein structure.

By identifying the mechanisms of formation of antibiotic resistance, we also found that in a large percentage of cases, the microbial cell becomes less permeable to the active drug. For example, streptococci have a natural barrier through which aminoglycosides cannot pass. Tetracycline drugs accumulate only in bacteria that are sensitive to them. When a life form is resistant, the compounds, in principle, cannot penetrate the pathogen’s body.

Developing resilience: nuances of the process

When determining antibiotic resistance, it is necessary to analyze specific microorganisms not only for the possibility of producing enzymes that inhibit the activity of the drug. Some bacteria can form compounds that destroy antibiotics. In particular, there are life forms whose resistance to cycloserine is explained by the release of alanine transferase.

Another subtle point is antibiotic resistance genes. It is known that microscopic life forms are capable of forming new metabolic mechanisms, creating a so-called metabolic shunt. This helps them avoid reactions that are affected by the drug composition.

In some cases, antibiotic resistance is an efflux-related phenomenon. The term usually refers to the process of active removal of an aggressive component from a microbial cell. The most striking representative of pathogens capable of this is Pseudomonas aeruginosa. Analysis and research have shown that resistant forms of this bacterium are capable of actively removing carbapenems from the microbial cell.

About causes and mechanisms

Currently, the problem of antibiotic resistance in Russia and in the world is becoming larger. It is customary to distinguish genetic and non-genetic resistance of pathological forms of life. The activity of bacterial replication largely determines the effectiveness of medications. Inactive in terms of metabolic processes, non-reproducing bacteria are resistant to the influence of medicinal compounds, but the offspring will remain sensitive.

It has been established that mycobacterium, which causes tuberculosis, exists for a long time (years) in the organic tissues of an infected person. During this entire period, it is useless to fight it with chemotherapy - the pathogen is resistant to any drugs. But at the moment when the carrier’s immunity is weakened and the mycobacterium begins to actively multiply, its offspring become sensitive to drugs.

In some cases, loss of antibiotic resistance is due to loss of a specific target. Some penicillin-sensitive microscopic life forms can transform into protoplasts when an antibiotic enters the microorganism, as a result of which the cell wall is lost. In the future, microbes may again acquire sensitivity to those drugs that inhibit cell wall synthesis: when returning to their parent form, the synthesis processes should resume, which leads to overcoming antibiotic resistance.

About genetics

Genetic antibiotic resistance is a phenomenon formed as a result of genetic transformations occurring in a microscopic organism. In some cases, resistance is explained by the specifics of metabolism. This form of resistance is divided into two groups: chromosomal and non-chromosomal.

Chromosomal resistance

This phenomenon can form as a result of a random mutation in the chromosome of a bacterium responsible for drug susceptibility. Antibiotics affect certain specific mechanisms, and resistance gradually develops. The mutants have absolute protection; under the influence of an external factor, the receptor structures are not rebuilt.

As a rule, a certain narrow chromosomal region has genes that encode receptors for antimicrobial compounds. For streptomycin, for example, this is the P12 protein structure on the 30S subunit. With gene mutations in which the characteristics of reactions with P12 change, resistance to streptomycin appears. Gene mutations can cause the receptor to be excluded from the structure of the microorganism. It has been revealed that some microorganisms have become resistant to penicillin drugs, since they no longer contain receptors in their structure that can perceive penicillin.

Extra- and extrachromosomal persistence

The development of such features is explained by genetic elements outside the chromosome. These can be round DNA molecules, plasmids, which account for up to 3% of the total weight of the chromosome. They contain unique genes, genes from other plasmids. Free plasmids are found in the bacterial cytoplasm or are integrated into the chromosome. Due to them, the pest usually gains resistance to the penicillin series and cephalosporins, since the genes contain the ability to form beta-lactamase. They also explain the enzymatic compounds that provide acetylation and phosphorylation of aminoglycosides. According to this logic, it is possible to develop resistance to the tetracycline series due to the impermeability of the microbial cell to the substance.

To transfer genetic information, plasmids resort to the processes of modification, transduction, conjugation, and transposition.

Cross-resistance is possible. They talk about this when a microscopic life form becomes resistant to various agents, the mechanisms of influence of which on microbes are similar to each other. This is more typical for drugs that have a similar chemical structure. In some cases, the cross phenomenon is also characteristic of substances whose chemical structures differ quite strongly. A typical example: erythromycin and lincomycin.

What to do?

As the problem of antibiotic resistance becomes more pressing, the scientific community is striving to develop new principles and treatments to overcome the complexity. As a rule, they take advantage of the possibilities of combination therapy, but it has certain disadvantages, and first of all, an increased frequency of side effects. A positive effect in a number of cases is observed when using fundamentally new drugs that show good results when strains are resistant to previously used drugs.

In order for the resistance of microorganisms to be overcome and the effectiveness of the therapeutic course to be increased, it is reasonable to resort to proven combinations of agents. If infection with life forms that produce beta-lactamase is detected, drugs that contain components that inhibit the activity of the enzyme should be used. For example, a similar feature was identified in clavulan and tazobactam. These substances have a rather weak antibacterial effect, but the inhibition process is irreversible, which allows the main antibiotic to be protected from the enzyme. Most often, clavulanic acid is prescribed in combination with amoxicillin or ticarcillin. In pharmacies, such drugs are presented under the trade names “Augmentin” and “Timentip”. Another reliable drug, Unazin, is based on ampicillin, which was protected through sulbactam.

Treatment price

Often, when choosing therapy, a decision is made to simultaneously take several types of drugs that have different mechanisms of influence on pathological forms of life. It is commonly said that the most effective antibiotic is the one that produces a sufficient effect in a minimal amount without provoking negative effects in the macroorganism. At present, there is simply no remedy in nature that ideally matches this description; along with the desired result, a negative effect is always observed.

In some cases, the side effects are quite strong, and this completely precludes the use of an antimicrobial drug in accordance with its intended purpose. As can be seen from the statistics, up to 40% of all cases of antibiotic use lead to complications, the majority of which (8 out of 10 cases) are allergic reactions, another 7% are poisoning. The classification of side effects into allergic ones, as well as those explained by the effect of the drug on the macroorganism and the effect on the immune system and positive microflora, has been accepted.

What will help?

Since resistance to various forms of drugs in microorganisms is becoming more common, before prescribing a therapeutic course it is necessary to resort to modern methods for determining antibiotic resistance so that the selected program shows the desired effect and relieves the patient of the pathogen. To test the supposed effectiveness, it is necessary to isolate a culture of a pathological life form and study it for susceptibility to a particular drug. Please take into account that in laboratory conditions and in practical use the results may be different. There are several explanations for this phenomenon, including the acidity of the body's environment, culture conditions, and the size of the colonies.

The main method for determining antibiotic resistance is laboratory testing. Recently, rapid tests have appeared for certain forms of pathogens.

Antibiotic resistance in bacterial infections is already affecting global health care. If effective measures are not taken, then the near future will look like the Apocalypse: more people will die due to drug resistance than are currently dying from cancer and diabetes combined. However, an abundance of new antibiotics does not appear on the market. Read about what ways there are to improve the work of antibiotics already in use, what the “Achilles heel” of bacteria is, and how fly larvae help scientists. Biomolecule also managed to obtain information from the company Superbug solutions Ltd about their discovery - the antibacterial agent M13, which has already passed the first tests on animals. Its combination with known antibiotics helps to effectively fight against gram-positive and gram-negative bacteria (including antibiotic-resistant ones), slow down the development of bacterial resistance to antibiotics and prevent the formation of biofilms.

A special project about humanity’s fight against pathogenic bacteria, the emergence of antibiotic resistance and a new era in antimicrobial therapy.

The sponsor of the special project is the developer of new highly effective binary antimicrobial drugs.

* - To make antibiotics great again(lit. “Make Antibiotics Great Again”) is a paraphrased campaign slogan of Donald Trump, the current US President, who, by the way, is not committed to supporting science and healthcare.

What to do if infections that humanity already knows how to treat get out of control and become dangerous again? Is there life in the post-antibiotic era? The WHO announced in April 2014 that we could be entering this era. Of particular concern is that antibiotic resistance has already become one of the main problems for doctors all over the world (its origins are described in detail in the first part of the special project - “ Antibiotics and antibiotic resistance: from antiquity to the present day"). This is especially common in intensive care units where multidrug-resistant microorganisms exist. The most common nosocomial pathogens with resistance have even been dubbed ESKAPE: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acetinobacter baumanni, Pseudomonas aeruginosa And Enterobacter spp.. In English there is a pun here: escape means "escape", that is, they are pathogens that escape from antibiotics. Difficulties arose primarily with gram-negative bacteria, since the structure of their shell makes it difficult for drugs to penetrate inside, and those molecules that have already been able to “break through” are pumped back out of the bacteria by special pump molecules.

In the world, enterococcal resistance has already appeared to the commonly used ampicillin and vancomycin. Resistance is developing even to the latest generation of antibiotics - daptomycin and linezolid. To process data for Russia, our compatriots are already creating a map of the sensitivity of microorganisms to antibiotics throughout the country, based on research by scientists from the Research Institute of Antimicrobial Chemotherapy, Research Institute of Agricultural Sciences and the Interregional Association for Clinical Microbiology and Antimicrobial Chemotherapy MAKMAH ( data is constantly updated).

Preventive measures are no longer able to combat the spread of antibiotic resistance, especially in the absence of new drugs. There are very few new antibiotics, including because the interest of pharmaceutical companies in their development has decreased. After all, who will do business with a drug that may soon leave the market if resistance develops to it (and in some cases it can develop in just two years)? This is simply not economically profitable.

Despite this, new means of combating bacteria are needed more than ever - ordinary people are the ones suffering from the current situation. Antibiotic resistance is already impacting morbidity, mortality, and the cost of patient care. This process can affect anyone: more money is spent on treatment, hospital stays are longer, and the risks of complications and death increase. The British estimate the global annual death toll to be at least 700 thousand people. According to the latest WHO data, three places in the list of the ten leading causes of death in the world are occupied by bacterial infections and/or diseases mediated by them. These are respiratory infections of the lower respiratory tract (3rd place according to the latest bulletin - for 2015 - 3.19 million people), diarrheal diseases (8th place - 1.39 million people) and tuberculosis (9th place - 1.37 million people). Of the 56.4 million deaths worldwide, this represents more than 10%.

A large-scale study estimates Review on Antimicrobial Resistance, commissioned by the British government, the future looks even more frightening. Global annual deaths due to antibiotic resistance will reach ten million by 2050 - a total of more than the current deaths from cancer and diabetes (8.2 million and 1.5 million, respectively). cm. rice. 1). The costs would cost the world a huge amount: up to 3.5% of its total GDP or up to $100 trillion. In the more foreseeable future, global GDP will decrease by 0.5% by 2020 and by 1.4% by 2030.

Figure 1. Global mortality by 2050 According to the calculations of the British study Review on Antimicrobial Resistance, more people will die from antibiotic resistance than from oncology and diabetes combined.

“If we can't do anything about it, then we are faced with an almost unthinkable scenario in which antibiotics stop working and we return to the dark ages of medicine.”, - commented David Cameron, the then current Prime Minister of Great Britain.

Another vision: new antibiotics that are not susceptible to resistance

How to deal with the resistance of pathogenic bacteria to antibiotics? The first thought that comes to mind is to make new antibiotics, resistance to which will not develop. This is what scientists are doing now: the main target of the drugs for them has become the cell wall of bacteria.

His Majesty Lipid-II

Figure 2. Biosynthesis of the bacterial cell wall and the targets of new antibiotics targeting different parts of this mechanism.
To see the picture in full size, click on it.

One of the best known lipid-II antibiotics used in clinical practice is vancomycin. For a long time, its monotherapy helped fight enterococci, but now bacteria are already developing resistance to it (the chronology can be seen in the first article in the series). They were especially successful at this E.faecium.

Cell wall: boarding!

Many new antibiotics target molecules involved in bacterial cell wall biosynthesis, including lipid II. This is not surprising: after all, it is the cell wall that plays the role of a kind of exoskeleton, protects against threats and stress from the outside, maintains shape, is responsible for mechanical stability, protects the protoplast from osmotic lysis and ensures cellular integrity. To maintain the function of this “protective fortification,” bacteria are constantly in the process of updating it.

An essential cell wall element is peptidoglycan. It is a polymer of linear glycan strands cross-linked through peptide bridges. In Gram-negative bacteria, the peptidoglycan layer is thin and additionally covered by an outer membrane. In gram-positive bacteria it is much thicker and acts as the main component of the cell wall. In addition, they have surface proteins and secondary polymers attached to the peptidoglycan framework: teichoic, lipoteichoic and teichuronic acids. In some bacteria, the cell wall may be additionally surrounded by a polysaccharide capsule.

To ensure cell viability during growth and division, precise coordination of cell wall destruction (hydrolysis) and biosynthesis is necessary. Failure of even one gear of this mechanism threatens to disrupt the entire process. This is what scientists are hoping for, developing drugs with targets in the form of molecules involved in the biosynthesis of the bacterial cell wall.

Vancomycin, move over

A new antibiotic that can successfully replace vancomycin is considered teixobactin. Publication by Kim Lewis ( Kim Lewis) and colleagues, where it was first talked about, thundered in Nature in 2015. A new method developed by scientists helped make this discovery. iChip : Bacteria from the soil were dispersed into individual cells on a metal plate and then returned to the same soil and environmental conditions from which the bacteria “came from.” In this way, it was possible to reproduce the growth of all microorganisms that live in the soil under natural conditions (Fig. 3).

Figure 3. General view of iChip ( a) and its components: central plate ( b ), which contains growing microorganisms, and semi-permeable membranes on each side, separating the plate from the environment, as well as two supporting side panels ( V ). A brief description of the method is in the text.
To see the picture in full size, click on it.

This method by Francis Collins ( Francis Collins), which the director of the US National Institutes of Health (NIH) (Maryland) called “brilliant” because it expands the ability to search for new antibiotics in soil, one of the richest sources of these drugs. Before iChip, the isolation of new potential antibiotics from soil bacteria was limited due to the complex process of growing them in the laboratory: no more than 0.5% of bacteria can grow under artificial conditions.

Teixobactin has a more extensive effect than vancomycin. It binds not only lipid-II, even in vancomycin-resistant bacteria, but also lipid-III, the precursor of WTA - wall teichoic acid. With this double whammy, it can further interfere with cell wall synthesis. So far in experiments in vitro The toxicity of teixobactin to eukaryotes was low, and the development of bacterial resistance to it was not detected. However, publications on its action against gram-positive enterococci in vivo not yet, and it does not work on gram-negative bacteria.

Since lipid II is such a good target for antibiotics, it is not surprising that teixobactin is by no means the only molecule targeting it. Other promising compounds that fight gram-positive bacteria are: nisin-like lipopeptides. Myself lowlands is a member of the lantibiotic family of antimicrobial peptides. It binds the pyrophosphate moiety of lipid-II and forms pores in the bacterial membrane, leading to cell lysis and death. Unfortunately, this molecule has poor stability in vivo and, due to its pharmacokinetic characteristics, is not suitable for systemic administration. For this reason, scientists have “improved” nisin in the direction they need, and the properties of the resulting nisin-like lipopeptides are now being studied in laboratories.

Another molecule with good prospects is microbisporicin, blocking the biosynthesis of peptidoglycan and causing the accumulation of its precursor in the cell. Microbisporicin is called one of the most powerful lantibiotics known, and it can affect not only gram-positive bacteria, but also some gram-negative pathogens.

Not lipid-II alone

Lipid-II is good for everyone, and molecules that target its unchanged pyrophosphate are especially promising. However, by changing the peptide part of lipid II, bacteria achieve the development of resistance to therapy. So, drugs that target it (such as vancomycin) stop working. Then, instead of lipid-II, one has to look for other drug targets in the cell wall. This, for example, is undecaprenyl phosphate, an essential part of the peptidoglycan biosynthesis pathway. Several undecaprenyl phosphate synthase inhibitors are currently being studied - they may work well on gram-positive bacteria.

Antibiotics can also target other molecules, such as cell wall teichoic acids ( wall teachoic acid, WTA- it was mentioned above), lipoteichoic acids ( lipoteichoic acid, LTA) and surface proteins with amino acid motif LPxTG(leucine (L) - proline (P) - any amino acid (X) - threonine (T) - glycine (G)). Their synthesis is not vital for enterococci, unlike the production of peptidoglycan. However, knockout of genes involved in these pathways leads to serious impairments in bacterial growth and viability, and also reduces their virulence. Drugs targeting these surface structures could not only restore sensitivity to conventional antibiotics and prevent the development of resistance, but also become an independent class of drugs.

Among the completely new agents we can name a group oxazolidinones and its representatives: linezolid, tedizolid, cadazolid. These synthetic antibiotics bind the 23S rRNA molecule of the bacterial ribosome and interfere with normal protein synthesis - without which, of course, the microorganism will have a bad time. Some of them are already used in the clinic.

Thus, the different components of a bacterial cell provide scientists with a rich choice of targets for drug development. But it is difficult to determine which products will “grow” into a product ready for the market. A small part of these - for example, tedizolid - is already used in clinical practice. However, most are still in the early stages of development and have not even been tested in clinical trials - and without them, the final safety and effectiveness of the drugs is difficult to predict.

Larvae against bacteria

Other antimicrobial peptides (AMPs) are also attracting attention. Biomolecule has already published a large review about antimicrobial peptides and a separate article about Lugdunin .

AMPs are called “natural antibiotics” because they are produced in animals. For example, various defensins - one of the groups of AMPs - are found in mammals, invertebrates and plants. A study has just been released that has identified a molecule in bee royal jelly that has been successfully used in folk medicine to heal wounds. It turned out that this is defensin-1 - it promotes re-epithelialization in vitro And in vivo .

Surprisingly, one of the human defense peptides is cathelicidin- turned out to be extremely similar to beta-amyloid, which has long been “blamed” for the development of Alzheimer’s disease.

Further research into natural AMPs may help find new drugs. They may even help solve the problem of drug resistance, since some such compounds found in nature do not develop resistance. For example, a new peptide antibiotic has just been discovered while studying Klebsiella pneumoniae subsp. ozaenae- an opportunistic human bacterium, one of the causative agents of pneumonia. He was named klebsazolicin (klebsazolicin, KLB). The way it works is as follows: it inhibits protein synthesis by binding to the bacterial ribosome in the peptide exit “tunnel,” the space between the ribosome subunits. Its effectiveness has already been demonstrated in vitro. What is noteworthy is that the authors of the discovery are Russian researchers from various scientific institutions in Russia and the USA.

However, perhaps out of the entire animal world, insects are now being studied the most. Hundreds of their species have been widely used in folk medicine since ancient times - in China, Tibet, India, South America and other parts of the world. Moreover, even now you can hear about “biosurgery” - the treatment of wounds with larvae Lucilia sericata or other flies. Surprising as it may seem to a modern patient, planting larvae in a wound used to be a popular therapy. When insects entered the area of ​​inflammation, they ate dead tissue, sterilized the wounds and accelerated their healing.

Researchers from St. Petersburg State University under the leadership of Sergei Chernysh are now actively working on a similar topic - only without live, swarming larvae. Scientists study a complex of AMPs produced by the larvae of the red-headed blue carrion (adult - in Fig. 4). It includes a combination of peptides from four families: defensins, cecropins, diptericins and proline-rich peptides. The first are aimed primarily at the membranes of gram-positive bacteria, the second and third - at gram-negative ones, and the latter are aimed at intracellular targets. Perhaps this mix arose during the evolution of flies precisely in order to increase the efficiency of the immune response and protect against the development of resistance.

Figure 4. Red-headed Blue Carrion . Its larvae may provide humanity with antimicrobial peptides that do not cause resistance.

Moreover, such AMPs are effective against biofilms - colonies of interconnected microorganisms living on any surface. It is these communities that are responsible for most bacterial infections and for the development of many serious complications in humans, including chronic inflammatory diseases. Once antibiotic resistance occurs in such a colony, it becomes extremely difficult to overcome. Russian scientists called the drug, which contains larval AMPs FLIP7. So far, experiments show that it can successfully join the ranks of antimicrobial drugs. Whether future experiments will confirm this, and whether this medicine will reach the market is a question for the future.

New - recycled old?

In addition to inventing new drugs, another obvious option arises - to change existing drugs so that they work again, or to change the strategy for their use. Of course, scientists are considering both of these options so that, to paraphrase the slogan of the current US President, to make antibiotics great again.

Silver bullet - or spoon?

James Collins ( James Collins) from Boston University (Massachusetts, USA) and colleagues are exploring how to increase the effectiveness of antibiotics by adding silver in the form of dissolved ions. The metal has been used for antiseptic purposes for thousands of years, and a US team decided the ancient method could help tackle the dangers of antibiotic resistance. According to researchers, a modern antibiotic with the addition of a small amount of silver can kill 1000 times more bacteria!

This effect is achieved in two ways.

First, the addition of silver increases the permeability of the membrane to drugs, even in gram-negative bacteria. As Collins himself says, silver turns out to be not so much a “silver bullet” that kills “evil spirits” - bacteria - but rather a silver spoon that “ helps gram-negative bacteria take medications».

Secondly, it disrupts the metabolism of microorganisms, resulting in the formation of too many reactive oxygen species, which, as is known, destroy everything around with their aggressive behavior.

Antibiotic cycle

Another method is suggested by Miriam Barlow ( Miriam Barlow) from the University of California (Merced, USA). Often, for evolutionary reasons, resistance to one antibiotic makes bacteria more vulnerable to other antibiotics, their team says. Because of this, using existing antibiotics in a precisely defined order can force the bacterial population to develop in the opposite direction. Barlow's group studied E. coli a specific resistance gene encoding the bacterial enzyme β-lactamase in various genotypes. To do this, they created a mathematical model that revealed that there is a 60–70% probability of returning to the original variant of the resistance gene. In other words, if treatment is applied correctly, the bacteria will again become sensitive to drugs to which it has already developed resistance. Some hospitals are already trying to implement a similar idea of ​​​​an “antibiotic cycle” with a change in treatment, but so far, according to the researcher, these attempts have lacked a proven strategy.

Wedge by wedge - bacterial methods

Another interesting development that could help antibiotics in their difficult work is the so-called “microbial technologies” ( microbial technology). As scientists have found, infection with antibiotic-resistant infections can often be associated with dysfunction of the intestinal microbiome - the totality of all microorganisms in the intestines.

A healthy intestine is home to a great variety of bacteria. When antibiotics are used, this diversity decreases, and the vacated “spaces” can be taken by pathogens. When there are too many of them, the integrity of the intestinal barrier is compromised, and pathogenic bacteria can get through it. Thus, the risk of catching an infection from the inside and, accordingly, getting sick increases significantly. Moreover, the likelihood of transmitting resistant pathogens to other people also increases.

To combat this, you can try to get rid of specific pathogenic strains that cause chronic infections, for example, using bacteriophages, the viruses of the bacteria themselves. The second option is to resort to the help of commensal bacteria that suppress the growth of pathogens and restore healthy intestinal microflora.

This method would reduce the risk of treatment side effects and the development of chronic problems associated with an unhealthy microbiome. It could also make antibiotics last longer by not increasing the risk of resistance developing. Finally, the risk of getting sick would be reduced both for the patient himself and for other people. However, it is still difficult to say for sure which strains of bacteria would provide greater benefit to the patient in terms of safety and effectiveness. Moreover, scientists doubt whether, at the current level of technology, it will be possible to establish the production and cultivation of microorganisms on the required scale.

By the way, it is interesting that the bacteria of the human microbiome themselves produce substances that kill other bacteria. They are called bacteriocins, and “Biomolecule” talked about them separately.

Agent M13 - what is hidden under the code name?

Another promising development that can complement existing drugs is a phenolic lipid called M13, the result of research by Russian scientists from the company Superbug Solutions Ltd, registered in Britain.

Compounds that are “attached” to an antibiotic and enhance its effect are called potentiators, or potentiating substances. There are two main mechanisms of their operation.

For researchers, potentiators are a very promising object because they fight bacteria that are already resistant to treatment, without requiring the development of new antibiotics and, on the contrary, they can return old antibiotics to the clinic.

Despite this, many of the mechanisms of operation of this class of substances are not fully understood. Therefore, before they are used in practice - if it comes to this - many more questions will need to be answered, including: how to make their impact specific and not affect the cells of the patient himself? Perhaps scientists will be able to select doses of the potentiator that will affect only bacterial cells and will not affect eukaryotic membranes, but only future research can confirm or refute this.

The research that culminated in the development of M13 began in the late 80s (now it is part of the Federal Research Center “Fundamental Foundations of Biotechnology” of the Russian Academy of Sciences), when, under the leadership of Galina El-Registan (now a scientific consultant for Superbug Solutions), factors were discovered in the USSR differentiation ( factors d1) - extracellular metabolites that regulate the growth and development of microbial populations and the formation of dormant forms. By their chemical nature, d1 factors are isomers and homologues of alkyloxybenzenes of the class alkylresorcinols , one of the types of phenolic lipids. It was found that they play the role of autoregulators, released by microorganisms into the environment to coordinate the interactions of population cells with each other and for communication with cells of other species that are part of the association or participate in symbiosis.

There are many ways that alkylresorcinols influence bacteria. At the molecular level they modify biopolymers. Thus, the enzyme apparatus of the cell suffers first. When alkylresorcinols bind to enzymes, the latter change the conformation, hydrophobicity and fluctuation of the domains of the protein globule. It turned out that in such a situation, not only the tertiary, but also the quaternary structure of proteins consisting of several subunits changes! A similar result of the addition of alkylresorcinols leads to a modification of the catalytic activity of proteins. The physicochemical characteristics of non-enzymatic proteins also change. In addition, alkylresorcinols also act on DNA. They cause a cellular response to stress at the level of activity of the genetic apparatus, which leads to the development of distress.

At the subcellular level, alkylresorcinols disrupt the native structure of the cell membrane. They increase the microviscosity of membrane lipids and inhibit NADH oxidase activity of membranes. The respiratory activity of microorganisms is blocked. The integrity of the membrane under the influence of alkylresorcinols is disrupted, and micropores appear in it. Due to the fact that K + and Na + ions with hydration shells leave the cell along the concentration gradient, dehydration and contraction of the cell occur. As a result, the membrane, under the influence of these substances, becomes inactive or inactive, and the energy and constructive metabolism of the cell is disrupted. The bacteria go into a state of distress. Their ability to withstand adverse factors, including exposure to antibiotics, decreases.

As scientists say, a similar effect on cells is achieved by exposure to low temperatures, to which they cannot fully adapt. This suggests that bacteria will also not be able to get used to the effects of alkylresorcinols. In the modern world, when antibiotic resistance worries the entire scientific community, this quality is extremely important.

The best results from the use of alkylresorcinols can be achieved by combining one or more of these molecules with antibiotics. For this reason, at the next stage of the experiment, Superbug Solutions scientists studied the effect of the combined effects of alkylresorcinols and antibiotics that differ in chemical structure and targets in the microbial cell.

First, the studies were carried out on pure laboratory cultures of non-pathogenic microorganisms. Thus, the minimum inhibitory concentration (the lowest concentration of a drug that completely inhibits the growth of microorganisms in the experiment) for antibiotics of seven different chemical groups against the main types of microorganisms decreased by 10–50 times in the presence of the studied alkylresorcinols. A similar effect was demonstrated for gram-positive and gram-negative bacteria and fungi. The number of bacteria surviving after treatment with a shock combination of high doses of antibiotic + alkylresorcinol was lower by 3–5 orders of magnitude compared to the action of the antibiotic alone.

Subsequent experiments on clinical isolates of pathogenic bacteria showed that the combination works here too: the minimum inhibitory concentration in some cases decreased by 500 times. Interestingly, an increase in the effectiveness of the antibiotic was observed in both drug-sensitive and resistant bacteria. Finally, the likelihood of the formation of antibiotic-resistant clones also decreased by an order of magnitude. In other words, the risk of developing antibiotic resistance is reduced or eliminated.

Thus, the developers have established that the effectiveness of treating infectious diseases using their “super bullet” scheme ( superbullet) - increases even if the disease was caused by antibiotic-resistant pathogens.

Having studied many alkylresorcinols, the researchers chose the most promising of them - M13. The compound acts on cells of both bacteria and eukaryotes, but in different concentrations. Resistance to the new agent also develops much more slowly than to antibiotics. The main mechanisms of its antimicrobial action, like other representatives of this group, are effects on membranes and enzymatic and non-enzymatic proteins.

It was found that the strength of the effect of adding M13 to antibiotics varies depending on both the type of antibiotic and the type of bacteria. To treat a specific disease, you will have to select your own pair “antibiotic + M13 or other alkylresorcinol”. As studies have shown in vitro, most often M13 exhibited synergism when interacting with ciprofloxacin and polymyxin. In general, the joint effect was noted less frequently in the case of gram-positive bacteria than in the case of gram-negative bacteria.

In addition, the use of M13 minimized the formation of antibiotic-resistant mutants of pathogenic bacteria. It is impossible to completely prevent their occurrence, but it is possible to significantly, by orders of magnitude, reduce the likelihood of their occurrence and increase sensitivity to the antibiotic, which is what the agent from Superbug Solutions did.

Based on the results of in vitro experiments, we can conclude that the most promising experiments are the use of a combination of M13 and antibiotics against gram-negative bacteria, which was studied further.

So, we conducted experiments in vivo to determine whether the effectiveness of treating infected mice with a combination of M13 with the known antibiotics polymyxin and amikacin is altered. Lethal Klebsiella infection caused by Klebsiella pneumoniae. As the first results showed, the effectiveness of antibiotics in combination with M13 actually increases. When mice were treated with M13 and an antibiotic (but not just one antibiotic), bacteremia was not observed in the spleen and blood. In further experiments on mice, the most effective combinations of M13 and other alkylresorcinols with certain antibiotics will be selected for the treatment of specific infections. Standard toxicology studies and phase 1 and 2 clinical trials will then be conducted.

The company is now filing a patent for the development and hopes for future accelerated approval of the drug from the FDA (American Food and Drug Administration). Superbug Solutions also has future experiments planned to study alkylresorcinols. The developers are going to further develop their platform for searching and creating new combination antimicrobial drugs. At the same time, many pharmaceutical companies have actually abandoned such developments, and today it is scientists and end consumers who are most interested in such research. The Superbug Solution company intends to attract them for support and development and, as a result, create a kind of community of involved and interested people. After all, who, if not the direct consumer of a potential drug, benefits from its entry into the market?

What's next?

Although forecasts for the fight against antibiotic-resistant infections are not yet very encouraging, the global community is trying to take measures to avoid the gloomy picture that experts paint for us. As discussed above, many scientific groups are developing new antibiotics or those drugs that, in combination with antibiotics, could successfully kill infections.

It would seem that there are many promising developments now. Preclinical experiments give hope that one day new drugs will “reach” the pharmaceutical market. However, it is already clear that the contribution of only developers of potential antibacterial drugs is not enough. It is also necessary to develop vaccines against certain pathogenic strains, review the methods used in animal husbandry, improve hygiene and diagnostic methods for diseases, educate the public about the problem and, most importantly, join forces to combat it (Figure 5). Much of this was discussed in the first part of the series.

It is not surprising that the Innovative Medicines Initiative ( Innovative Medicines Initiative, IMI) of the European Union, which facilitates cooperation between the pharmaceutical industry and leading scientific centers, announced the launch of the “New drugs against bad germs” program ( New Drugs 4 Bad Bugs, ND4BB). “The IMI program against antibiotic resistance is much more than clinical development of antibiotics, says Irene Norstedt ( Irene Norstedt), acting director of IMI. - It covers all areas from the basic science of antibiotic resistance (including the introduction of antibiotics into bacteria) through early stages of drug discovery and development to clinical trials and the creation of a pan-European clinical trials group.”. According to her, most parties involved in drug development, including industry and scientists, are already clear: problems on the scale of antimicrobial resistance can only be solved through everyone's cooperation. The program also includes finding new ways to avoid antibiotic resistance.

Other initiatives include the Global Action Plan on Antimicrobial Resistance and the annual Antibiotics: Use with Care! campaign. to raise awareness of the problem among medical personnel and the public. It appears that avoiding the post-antibiotic era may require a small contribution from anyone. Are you ready for this?

Superbug Solutions is a sponsor of a special project on antibiotic resistance

Company Superbug Solutions UK Ltd. ("Superbug Solutions", UK) is one of the leading companies engaged in unique research and development of solutions in the field of creating highly effective binary antimicrobial drugs of a new generation. In June 2017, Superbug Solutions received a certificate from the largest research and innovation program in the history of the European Union, Horizon 2020, certifying that the company’s technologies and developments are breakthroughs in the history of the development of research to expand the use of antibiotics.

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In recent years, the importance of studying microorganisms that can cause pathological changes in the human body has grown significantly. The relevance of the topic is determined by the increasing attention to the problem of microbial resistance to antibiotics, which is becoming one of the factors leading to curbing the widespread use of antibiotics in medical practice. This article is devoted to the study of the general picture of the isolated pathogens and the antibiotic resistance of the most common ones. During the work, data from bacteriological studies of biological material from patients of a clinical hospital and antibiograms for 2013-2015 were studied. According to the general information obtained, the number of isolated microorganisms and antibiograms is steadily growing. Based on the results obtained during the study of the resistance of isolated microorganisms to antibiotics of various groups, it is worth noting, first of all, its variability. To prescribe adequate therapy and prevent unfavorable outcomes, it is necessary to obtain timely data on the spectrum and level of antibiotic resistance of the pathogen in each specific case.

Microorganisms

antibiotic resistance

treatment of infections

1. Egorov N.S. Fundamentals of the doctrine of antibiotics - M.: Nauka, 2004. - 528 p.

2. Kozlov R.S. Current trends in antibiotic resistance of pathogens of nosocomial infections in Russian ICUs: what awaits us next? // Intensive care. No. 4-2007.

3. Guidelines MUK 4.2.1890-04. Determination of the sensitivity of microorganisms to antibacterial drugs - Moscow, 2004.

4. Sidorenko S.V. Research on the spread of antibiotic resistance: practical significance for medicine // Infections and antimicrobial therapy.-2002, 4(2): P.38-41.

5. Sidorenko S.V. Clinical significance of antibiotic resistance of gram-positive microorganisms // Infections and antimicrobial therapy. 2003, 5(2): pp.3–15.

In recent years, the importance of studying microorganisms that can cause pathological changes in the human body has grown significantly. New species are discovered and studied, their properties, influence on the integrity of the body, and the biochemical processes occurring in it. And along with this, attention is increasing to the problem of microbial resistance to antibiotics, which is becoming one of the factors leading to curbing the widespread use of antibiotics in medical practice. Various approaches to the practical use of these drugs are being developed to help reduce the emergence of resistant forms.

The purpose of our work was to study the general picture of the isolated pathogens and the antibiotic resistance of the most common ones.

During the work, data from bacteriological studies of biological material from patients of a clinical hospital and antibiograms for 2013-2015 were studied.

According to the general information obtained, the number of isolated microorganisms and antibiograms is steadily growing (Table 1).

Table 1. General information.

Basically, the following pathogens were isolated: about a third - Enterobacteriaceae, a third - Staphylococci, the rest (Streptococci, non-fermenting bacteria, Candida fungi) a little less. At the same time, gram-positive coccal flora was more often isolated from the upper respiratory tract, ENT organs, and wounds; gram-negative rods - most often from sputum, wounds, urine.

The pattern of antibiotic resistance of S.aureus over the years studied does not allow us to identify clear patterns, which is quite expected. For example, resistance to penicillin tends to decrease (however, it is at a fairly high level), and resistance to macrolides increases (Table 2).

Table 2. Resistance of S. aureus.

Penicillins
Methicillin
Vancomycin
Linezolid
Fluoroquinolones
Macrolides
Azithromycin
Aminoglycosides
Synercid
Nitrofurantoin
Trimetaprim/sulfamethoxazole
Tigecycline
Rifampicin

In accordance with the results obtained in the treatment of this pathogen, effective drugs (resistance to which is falling) are: Cephalosporins of the 1st-2nd generations, “Protected” Penicillins, Vancomycin, Linezolid, Aminoglycosides, Fluoroquinolones, Furans; undesirable - Penicillins, Macrolides.

As for the studied streptococci: group A pyogenic streptococcus remains highly sensitive to traditional antibiotics, that is, treatment with them is quite effective. Variations occur among group B or C streptococci isolated, with resistance gradually increasing (Table 3). For treatment, Penicillins, Cephalosporins, Fluoroquinolones should be used, and Macrolides, Aminoglycosides, Sulfonamides should not be used.

Table 3. Resistance of Streptococci.

Enterococci are more resistant by nature, so the range of choice of drugs is very narrow initially: “Protected” Penicillins, Vancomycin, Linezolid, Furans. According to the study results, there is no increase in resistance. “Simple” Penicillins and Fluoroquinolones remain undesirable for use. It is important to consider that Enterococci have species resistance to Macrolides, Cephalosporins, Aminoglycosides.

A third of the isolated clinically significant microorganisms are Enterobacteriaceae. Isolated from patients in the departments of Hematology, Urology, and Nephrology, they are often low-resistant, in contrast to those isolated from patients in intensive care units (Table 4), which is confirmed in all-Russian studies. When prescribing antimicrobial drugs, one should make a choice in favor of the following effective groups: “Protected” Amino- and Ureido-Penicillins, “Protected” Cephalosporins, Carbopenems, Furans. It is undesirable to use Penicillins, Cephalosporins, Fluoroquinolones, Aminoglycosides, resistance to which has increased in the last year.

Table 4. Resistance of Enterobacteriaceae.

Penicillins
Amoxicillin/clavulonate
Piperacillin/tazobactam
III (=IV) generation cephalosporins
Cefoperazone/sulbactam
Carbopenems
Meropenem
Fluoroquinolones
Aminoglycoside
Amikacin
Nitrofurantoin
Trimetaprim/sulfamethoxazole
Tigecycline

Based on the results obtained during the study of the resistance of isolated microorganisms to antibiotics of various groups, it is worth noting, first of all, its variability. Accordingly, a very important point is periodic monitoring of the dynamics and application of the obtained data in medical practice. To prescribe adequate therapy and prevent unfavorable outcomes, it is necessary to obtain timely data on the spectrum and level of antibiotic resistance of the pathogen in each specific case. Irrational prescription and use of antibiotics can lead to the emergence of new, more resistant strains.

Bibliographic link

Styazhkina S.N., Kuzyaev M.V., Kuzyaeva E.M., Egorova E.E., Akimov A.A. THE PROBLEM OF ANTIBIOTIC RESISTANCE OF MICROORGANISMS IN A CLINICAL HOSPITAL // International Student Scientific Bulletin. – 2017. – No. 1.;
URL: http://eduherald.ru/ru/article/view?id=16807 (access date: 01/30/2020). We bring to your attention magazines published by the publishing house "Academy of Natural Sciences"