home Audience 3 Causes of antibiotic resistance and methods to combat them. International student scientific bulletin. Bacteria as a weapon

Causes of antibiotic resistance and methods to combat them. International student scientific bulletin. Bacteria as a weapon

Antibiotics are one of the greatest achievements of medical science, saving the lives of tens and hundreds of thousands of people every year. However, as popular wisdom says, even an old woman can get screwed. What used to kill pathogens no longer works as well as before. So what is the reason: have antimicrobial drugs become worse or is antibiotic resistance to blame?

Determination of antibiotic resistance

Antimicrobial drugs (AMDs), commonly called antibiotics, were originally created to fight bacterial infections. And due to the fact that various diseases can be caused not by one, but by several varieties of bacteria combined into groups, the development of drugs effective against a certain group of infectious pathogens was initially carried out.

But bacteria, although the simplest, are actively developing organisms, acquiring more and more new properties over time. The instinct of self-preservation and the ability to adapt to different living conditions make pathogenic microorganisms stronger. In response to a threat to life, they begin to develop the ability to resist it, secreting a secret that weakens or completely neutralizes the effect of the active substance of antimicrobial drugs.

It turns out that once effective antibiotics simply cease to perform their function. In this case, they talk about the development of antibiotic resistance to the drug. And the point here is not at all in the effectiveness of the active substance AMP, but in the mechanisms for improving pathogens, thanks to which bacteria become insensitive to antibiotics designed to fight them.

So, antibiotic resistance is nothing more than a decrease in the susceptibility of bacteria to antimicrobial drugs that were created to destroy them. It is for this reason that treatment with seemingly correctly selected drugs does not give the expected results.

The problem of antibiotic resistance

The lack of effect of antibiotic therapy, associated with antibiotic resistance, leads to the fact that the disease continues to progress and becomes more severe, the treatment of which becomes even more difficult. Of particular danger are cases when a bacterial infection affects vital organs: heart, lungs, brain, kidneys, etc., because in this case, delay in death is similar.

The second danger is that some diseases, if antibiotic therapy is insufficient, can become chronic. A person becomes a carrier of improved microorganisms that are resistant to antibiotics of a certain group. It is now a source of infection, and it becomes pointless to fight it using old methods.

All this pushes pharmaceutical science to invent new, more effective products with other active ingredients. But the process again goes in circles with the development of antibiotic resistance to new drugs from the category of antimicrobial agents.

If anyone thinks that the problem of antibiotic resistance has arisen only recently, they are very mistaken. This problem is as old as time. Well, perhaps not that much, and yet she is already 70-75 years old. According to the generally accepted theory, it appeared along with the introduction of the first antibiotics into medical practice somewhere in the 40s of the twentieth century.

Although there is a concept of an earlier appearance of the problem of microbial resistance. Before the advent of antibiotics, this problem was not particularly addressed. After all, it is so natural that bacteria, like other living beings, tried to adapt to unfavorable environmental conditions and did it in their own way.

The problem of resistance of pathogenic bacteria came to light when the first antibiotics appeared. True, then the question was not yet so pressing. During that period, various groups of antibacterial agents were actively being developed, which was in some way due to the unfavorable political situation in the world, military operations, when soldiers died from wounds and sepsis only because they could not receive effective assistance due to the lack of necessary drugs. These drugs simply did not exist yet.

The greatest number of developments was carried out in the 50-60s of the twentieth century, and over the next 2 decades they were improved. Progress did not end there, but since the 80s, developments regarding antibacterial agents have become noticeably less. Whether this is due to the high cost of this enterprise (the development and release of a new drug in our time reaches the limit of 800 million dollars) or the banal lack of new ideas regarding “militant-minded” active substances for innovative drugs, but in this regard the problem of antibiotic resistance is emerging to a new scary level.

By developing promising AMPs and creating new groups of such drugs, scientists hoped to defeat multiple types of bacterial infections. But everything turned out to be not so simple “thanks” to antibiotic resistance, which is developing quite quickly in certain strains of bacteria. Enthusiasm is gradually drying up, but the problem remains unresolved for a long time.

It remains unclear how microorganisms can develop resistance to drugs that were supposed to kill them? Here you need to understand that “killing” bacteria occurs only when the drug is used as intended. But what do we really have?

Causes of antibiotic resistance

Here we come to the main question: who is to blame for the fact that bacteria, when exposed to antibacterial agents, do not die, but are actually reborn, acquiring new properties that are far from beneficial to humanity? What provokes such changes that occur in microorganisms that are the cause of many diseases that humanity has been struggling with for decades?

It is clear that the true reason for the development of antibiotic resistance is the ability of living organisms to survive in different conditions, adapting to them in different ways. But bacteria do not have the opportunity to dodge the deadly projectile in the form of an antibiotic, which in theory should bring death to them. So how is it that they not only survive, but also improve in parallel with the improvement of pharmaceutical technologies?

You need to understand that if there is a problem (in our case, the development of antibiotic resistance in pathogenic microorganisms), then there are provoking factors that create the conditions for it. It is precisely this issue that we will now try to understand.

Factors in the development of antibiotic resistance

When a person comes to a doctor with health complaints, he expects qualified help from a specialist. When it comes to respiratory tract infections or other bacterial infections, the doctor’s task is to prescribe an effective antibiotic that will prevent the disease from progressing, and to determine the dosage required for this purpose.

The doctor’s choice of medications is quite large, but how to determine exactly the drug that will really help cope with the infection? On the one hand, to justify the prescription of an antimicrobial drug, it is necessary to first find out the type of causative agent of the disease, according to the etiotropic concept of choosing a drug, which is considered the most correct. But on the other hand, this can take up to 3 or more days, while timely therapy in the early stages of the disease is considered the most important condition for successful recovery.

The doctor has no choice but to act almost at random in the first days, in order to somehow slow down the disease and prevent it from spreading to other organs (empirical approach). When prescribing outpatient treatment, the practitioner assumes that the causative agent of a particular disease may be certain types of bacteria. This is the reason for the initial choice of the drug. The prescription may change depending on the results of the pathogen analysis.

And it’s good if the doctor’s prescription is confirmed by test results. Otherwise, not only time will be lost. The fact is that for successful treatment there is another necessary condition - complete deactivation (in medical terminology there is the concept of “irradiation”) of pathogenic microorganisms. If this does not happen, the surviving microbes will simply “get sick”, and they will develop a kind of immunity to the active substance of the antimicrobial drug that caused their “disease”. This is as natural as the production of antibodies in the human body.

It turns out that if the antibiotic is chosen incorrectly or the dosing regimen and administration of the drug are ineffective, pathogenic microorganisms may not die, but change or acquire capabilities previously unknown to them. By multiplying, such bacteria form entire populations of strains that are resistant to antibiotics of a particular group, i.e. antibiotic-resistant bacteria.

Another factor that negatively affects the susceptibility of pathogenic microorganisms to antibacterial drugs is the use of AMPs in animal husbandry and veterinary medicine. The use of antibiotics in these areas is not always justified. In addition, the determination of the causative agent of the disease in most cases is not carried out or is carried out with a delay, because antibiotics are used mainly to treat animals that are in a rather serious condition, when timing is everything, and it is not possible to wait for test results. But in a village, the veterinarian does not always even have such an opportunity, so he acts “blindly.”

But this would be nothing, only there is another big problem - the human mentality, when everyone is their own doctor. Moreover, the development of information technology and the ability to purchase most antibiotics without a doctor’s prescription only aggravate this problem. And if we consider that we have more unqualified, self-taught doctors than those who strictly follow the doctor’s prescriptions and recommendations, the problem takes on global proportions.

Mechanisms of antibiotic resistance

Recently, antibiotic resistance has become the number one problem in the pharmaceutical industry involved in the development of antimicrobial drugs. The thing is that it is characteristic of almost all known varieties of bacteria, and therefore antibiotic therapy is becoming less and less effective. Such common pathogenic microorganisms as staphylococci, Escherichia coli, Pseudomonas aeruginosa, and Proteus have resistant strains that are more common than their ancestors exposed to antibiotics.

Resistance to different groups of antibiotics, and even to individual drugs, develops differently. The good old penicillins and tetracyclines, as well as newer developments in the form of cephalosporins and aminoglycosides, are characterized by the slow development of antibiotic resistance, and in parallel with this, their therapeutic effect decreases. The same cannot be said about such drugs, the active ingredients of which are streptomycin, erythromycin, rifampicin and lincomycin. Resistance to these drugs develops at a rapid pace, and therefore the prescription has to be changed even during the course of treatment, without waiting for its completion. The same applies to the drugs oleandomycin and fusidine.

All this suggests that the mechanisms of development of antibiotic resistance to different drugs differ significantly. Let's try to figure out what properties of bacteria (natural or acquired) do not allow antibiotics to eliminate them, as originally intended.

To begin with, let’s determine that resistance in a bacterium can be natural (the protective functions bestowed upon it initially) and acquired, which we discussed above. Until now, we have mainly talked about true antibiotic resistance, which is associated with the characteristics of the microorganism, and not with incorrect choice or prescription of the drug (in this case we are talking about false antibiotic resistance).

Every living creature, including protozoa, has its own unique structure and some properties that allow it to survive. All this is genetically determined and passed on from generation to generation. Natural resistance to specific active ingredients of antibiotics is also genetically determined. Moreover, in different types of bacteria, resistance is aimed at a specific type of drug, which is why the development of different groups of antibiotics that affect a particular type of bacteria is associated.

Factors that determine natural resistance can be different. For example, the structure of the protein shell of a microorganism may be such that an antibiotic cannot cope with it. But antibiotics can only affect the protein molecule, destroying it and causing the death of the microorganism. The development of effective antibiotics involves taking into account the structure of bacterial proteins against which the drug is targeted.

For example, antibiotic resistance of staphylococci against aminoglycosides is due to the fact that the latter cannot penetrate the microbial membrane.

The entire surface of the microbe is covered with receptors, with certain types of which AMPs bind. A small number of suitable receptors or their complete absence leads to the fact that binding does not occur, and therefore there is no antibacterial effect.

Among other receptors, there are those that serve as a kind of beacon for the antibiotic, signaling the location of the bacterium. The absence of such receptors allows the microorganism to hide from danger in the form of AMPs, which is a kind of camouflage.

Some microorganisms have the natural ability to actively remove AMPs from the cell. This ability is called efflux and it characterizes the resistance of Pseudomonas aeruginosa to carbapenems.

Biochemical mechanism of antibiotic resistance

In addition to the natural mechanisms for the development of antibiotic resistance listed above, there is another one related not to the structure of the bacterial cell, but to its functionality.

The fact is that bacteria can produce enzymes in the body that can have a negative effect on the molecules of the active substance of AMP and reduce its effectiveness. Bacteria also suffer when interacting with such an antibiotic; their effect is noticeably weakened, which creates the appearance of a cure for the infection. However, the patient remains a carrier of the bacterial infection for some time after the so-called “recovery”.

In this case, we are dealing with a modification of the antibiotic, as a result of which it becomes inactive against this type of bacteria. The enzymes produced by different types of bacteria may differ. Staphylococci are characterized by the synthesis of beta-lactamase, which provokes rupture of the lactem ring of penicillin antibiotics. The production of acetyltransferase can explain the resistance of gram-negative bacteria to chloramphenicol, etc.

Acquired antibiotic resistance

Bacteria, like other organisms, are no strangers to evolution. In response to “military” actions against them, microorganisms can change their structure or begin to synthesize such an amount of an enzyme substance that can not only reduce the effectiveness of the drug, but also destroy it completely. For example, the active production of alanine transferase makes Cycloserine ineffective against bacteria that produce it in large quantities.

Antibiotic resistance can also develop as a result of modification in the structure of the cell protein, which is also its receptor, with which AMP must bind. Those. this type of protein may be absent from the bacterial chromosome or change its properties, as a result of which the connection between the bacterium and the antibiotic becomes impossible. For example, loss or modification of the penicillin-binding protein causes insensitivity to penicillins and cephalosporins.

As a result of the development and activation of protective functions in bacteria previously exposed to the destructive effects of a certain type of antibiotic, the permeability of the cell membrane changes. This can be accomplished by reducing the channels through which the active substances of AMPs can penetrate into the cell. It is these properties that determine the insensitivity of streptococci to beta-lactam antibiotics.

Antibiotics can affect the cellular metabolism of bacteria. In response to this, some microorganisms have learned to do without chemical reactions that are affected by the antibiotic, which is also a separate mechanism for the development of antibiotic resistance that requires constant monitoring.

Sometimes bacteria use a certain trick. By attaching to a dense substance, they form communities called biofilms. Within a community, they are less sensitive to antibiotics and can easily tolerate dosages that are lethal for an individual bacterium living outside the “collective.”

Another option is to group microorganisms into groups on the surface of a semi-liquid medium. Even after cell division, part of the bacterial “family” remains within the “group”, which is not affected by antibiotics.

Antibiotic resistance genes

There are concepts of genetic and non-genetic drug resistance. We deal with the latter when we consider bacteria with inactive metabolism, which are not prone to reproduction under normal conditions. Such bacteria can develop antibiotic resistance to certain types of drugs, however, this ability is not passed on to their offspring, since it is not genetically determined.

This is characteristic of pathogenic microorganisms that cause tuberculosis. A person can become infected and not suspect the disease for many years until his immunity, for some reason, fails. This is the impetus for the proliferation of mycobacteria and the progression of the disease. But the same drugs are used to treat tuberculosis, although the bacterial offspring still remain sensitive to them.

The situation is exactly the same with the loss of protein in the cell wall of microorganisms. Let us again remember about bacteria sensitive to penicillin. Penicillins inhibit the synthesis of proteins that serve to build the cell membrane. Under the influence of penicillin-type AMPs, microorganisms can lose their cell wall, the building material of which is penicillin-binding protein. Such bacteria become resistant to penicillins and cephalosporins, which now have nothing to bind to. This phenomenon is temporary and not associated with gene mutation and inheritance of the modified gene. With the appearance of the cell wall characteristic of previous populations, antibiotic resistance in such bacteria disappears.

Genetic antibiotic resistance is said to occur when changes in cells and metabolism within them occur at the gene level. Gene mutations can cause changes in the structure of the cell membrane, provoke the production of enzymes that protect bacteria from antibiotics, and also change the number and properties of bacterial cell receptors.

There are 2 ways of development of events here: chromosomal and extrachromosomal. If a gene mutation occurs on the part of the chromosome that is responsible for sensitivity to antibiotics, we speak of chromosomal antibiotic resistance. Such a mutation itself occurs extremely rarely; it is usually caused by the action of drugs, but again not always. It is very difficult to control this process.

Chromosomal mutations can be passed on from generation to generation, gradually forming certain strains (varieties) of bacteria resistant to a particular antibiotic.

Extrachromosomal antibiotic resistance is caused by genetic elements that exist outside the chromosomes and are called plasmids. It is these elements that contain the genes responsible for the production of enzymes and the permeability of the bacterial wall.

Antibiotic resistance most often results from horizontal gene transfer, where some bacteria pass on some genes to others that are not their descendants. But sometimes unrelated point mutations can be observed in the genome of the pathogen (size 1 in 108 per process of copying the DNA of the mother cell, which is observed during chromosome replication).

Thus, in the fall of 2015, scientists from China described the MCR-1 gene, found in pork meat and the intestines of pigs. The peculiarity of this gene is the possibility of its transmission to other organisms. After some time, the same gene was found not only in China, but also in other countries (USA, England, Malaysia, European countries).

Antibiotic resistance genes can stimulate the production of enzymes that were not previously produced in the body of bacteria. For example, the enzyme NDM-1 (metallo-beta-lactamase 1), discovered in the bacteria Klebsiella pneumoniae in 2008. It was first discovered in bacteria native to India. But in subsequent years, the enzyme that provides antibiotic resistance to most AMPs was identified in microorganisms in other countries (Great Britain, Pakistan, USA, Japan, Canada).

Pathogenic microorganisms can exhibit resistance both to certain drugs or groups of antibiotics, and to different groups of drugs. There is such a thing as cross-antibiotic resistance, when microorganisms become insensitive to drugs with a similar chemical structure or mechanism of action on bacteria.

Antibiotic resistance of staphylococci

Staphylococcal infection is considered one of the most common community-acquired infections. However, even in a hospital setting, about 45 different strains of staphylococcus can be found on the surfaces of various objects. This suggests that the fight against this infection is almost the primary task of health workers.

The difficulty in performing this task is that most strains of the most pathogenic staphylococci, Staphylococcus epidermidis and Staphylococcus aureus, are resistant to many types of antibiotics. And the number of such strains is growing every year.

The ability of staphylococci to undergo multiple genetic mutations depending on living conditions makes them practically invulnerable. Mutations are passed on to descendants, and in a short time, entire generations of infectious pathogens from the genus Staphylococcus, resistant to antimicrobial drugs, appear.

The biggest problem is methicillin-resistant strains, which are resistant not only to beta-lactams (beta-lactam antibiotics: certain subgroups of penicillins, cephalosporins, carbapenems and monobactams), but also to other types of AMPs: tetracyclines, macrolides, lincosamides, aminoglycosides, fluoroquinolones, chloramphenicol.

For a long time, it was possible to destroy the infection only with the help of glycopeptides. Currently, the problem of antibiotic resistance of such staphylococcal strains is being solved through a new type of AMP – oxazolidinones, of which linezolid is a prominent representative.

Methods for determining antibiotic resistance

When creating new antibacterial drugs, it is very important to clearly define its properties: how they act and against which bacteria they are effective. This can only be determined through laboratory tests.

Antibiotic resistance testing can be carried out using various methods, the most popular of which are:

Disc method, or diffusion of AMPs into agar according to Kirby-Bayer
Serial dilution method
Genetic identification of mutations causing drug resistance.

The first method is considered the most common today due to its low cost and ease of implementation. The essence of the disk method is that bacterial strains isolated as a result of research are placed in a nutrient medium of sufficient density and covered with paper disks soaked in an AMP solution. The concentration of the antibiotic on the disks is different, so when the drug diffuses into the bacterial environment, a concentration gradient can be observed. Based on the size of the zone of absence of microorganism growth, one can judge the activity of the drug and calculate the effective dosage.

A variant of the disk method is the E-test. In this case, instead of disks, polymer plates are used, onto which a certain concentration of antibiotic is applied.

The disadvantages of these methods are the inaccuracy of calculations associated with the dependence of the concentration gradient on various conditions (medium density, temperature, acidity, calcium and magnesium content, etc.).

The serial dilution method is based on creating several versions of a liquid or solid medium containing different concentrations of the drug being studied. Each of the options is populated with a certain amount of the bacterial material being studied. At the end of the incubation period, bacterial growth or lack thereof is assessed. This method allows you to determine the minimum effective dose of the drug.

The method can be simplified by taking only 2 media as a sample, the concentration of which will be as close as possible to the minimum required to inactivate bacteria.

The serial dilution method is rightfully considered the gold standard for determining antibiotic resistance. But due to its high cost and labor intensity, it is not always applicable in domestic pharmacology.

The mutation identification method provides information about the presence of modified genes in a particular strain of bacteria that contribute to the development of antibiotic resistance to specific drugs, and in this regard, systematize emerging situations taking into account the similarity of phenotypic manifestations.

This method is characterized by the high cost of test systems for its implementation, however, its value for predicting genetic mutations in bacteria is undeniable.

No matter how effective the above methods for studying antibiotic resistance are, they cannot fully reflect the picture that will unfold in a living organism. And if we also take into account the fact that each person’s body is individual, the processes of distribution and metabolism of drugs can take place in it differently, the experimental picture can be very far from the real one.

Ways to overcome antibiotic resistance

No matter how good this or that drug is, given our current attitude to treatment, we cannot exclude the fact that at some point the sensitivity of pathogenic microorganisms to it may change. The creation of new drugs with the same active ingredients also does not solve the problem of antibiotic resistance. And the sensitivity of microorganisms to new generations of drugs gradually weakens due to frequent unjustified or incorrect prescriptions.

A breakthrough in this regard is considered to be the invention of combination drugs, which are called protected drugs. Their use is justified against bacteria that produce enzymes that are destructive to conventional antibiotics. Popular antibiotics are protected by including special agents in the new drug (for example, enzyme inhibitors that are dangerous for a certain type of AMP), which stop the production of these enzymes by bacteria and prevent the drug from being removed from the cell through a membrane pump.

Clavulanic acid or sulbactam are commonly used as beta-lactamase inhibitors. They are added to beta-lactam antibiotics, thereby increasing the effectiveness of the latter.

Currently, drugs are being developed that can act not only on individual bacteria, but also on those that have formed groups. Bacteria within a biofilm can be combated only after it has been destroyed and organisms previously linked through chemical signals have been released. In terms of the possibility of destroying biofilm, scientists are considering a type of drug such as bacteriophages.

The fight against other bacterial “groups” is carried out by transferring them to a liquid medium, where microorganisms begin to exist separately, and now they can be fought with conventional drugs.

Faced with the phenomenon of resistance during drug treatment, doctors solve the problem by prescribing various drugs that are effective against isolated bacteria, but with different mechanisms of action on pathogenic microflora. For example, they simultaneously use drugs with bactericidal and bacteriostatic effects or replace one drug with another from a different group.

Prevention of antibiotic resistance

The main goal of antibiotic therapy is the complete destruction of the population of pathogenic bacteria in the body. This problem can be solved only by prescribing effective antimicrobial drugs.

The effectiveness of the drug is accordingly determined by the spectrum of its activity (whether the identified pathogen is included in this spectrum), the ability to overcome the mechanisms of antibiotic resistance, and the optimally selected dosage regimen, which causes the death of pathogenic microflora. In addition, when prescribing a drug, the likelihood of side effects and the availability of treatment for each individual patient must be taken into account.

In an empirical approach to the treatment of bacterial infections, it is not possible to take into account all these points. High professionalism of the doctor and constant monitoring of information about infections and effective drugs to combat them are required so that the prescription does not turn out to be unjustified and does not lead to the development of antibiotic resistance.

The creation of medical centers equipped with high-tech equipment makes it possible to practice etiotropic treatment, when the pathogen is first identified in a shorter time, and then an effective drug is prescribed.

Antibiotic resistance can also be prevented by controlling the prescription of drugs. For example, in case of ARVI, the prescription of antibiotics is not justified in any way, but it contributes to the development of antibiotic resistance of microorganisms that are for the time being in a “dormant” state. The fact is that antibiotics can provoke a weakening of the immune system, which in turn will cause the proliferation of a bacterial infection buried inside the body or entering it from the outside.

It is very important that the drugs prescribed correspond to the goal that needs to be achieved. Even a drug prescribed for preventive purposes must have all the properties necessary to destroy pathogenic microflora. Choosing a drug at random may not only not give the expected effect, but also aggravate the situation by the development of resistance to the drug of a certain type of bacteria.

Particular attention should be paid to the dosage. Small doses that are ineffective to fight infection again lead to the development of antibiotic resistance in pathogens. But you should also not overdo it, because with antibiotic therapy there is a high probability of developing toxic effects and anaphylactic reactions that are life-threatening to the patient. Moreover, if the treatment is carried out on an outpatient basis in the absence of supervision from medical staff.

Through the media, it is necessary to convey to people the danger of self-medication with antibiotics, as well as incomplete treatment, when bacteria do not die, but only become less active with a developed mechanism of antibiotic resistance. Cheap unlicensed drugs, which illegal pharmaceutical companies position as low-cost analogues of existing drugs, have the same effect.

A highly effective measure for the prevention of antibiotic resistance is considered to be constant monitoring of existing infectious pathogens and the development of antibiotic resistance in them, not only at the district or regional level, but also throughout the country (and even the whole world). Alas, one can only dream about this.

In Ukraine, there is no infection control system as such. Only certain provisions have been adopted, one of which (back in 2007!), concerning obstetric hospitals, provides for the introduction of various methods for monitoring nosocomial infections. But everything again comes down to finances, and such studies are generally not carried out locally, not to mention doctors from other branches of medicine.

In the Russian Federation, the problem of antibiotic resistance has been treated with greater responsibility, and proof of this is the project “Map of Antimicrobial Resistance in Russia.” Research in this area, collection of information and its systematization to fill out the map of antibiotic resistance were carried out by such large organizations as the Research Institute of Antimicrobial Chemotherapy, the Interregional Association of Microbiology and Antimicrobial Chemotherapy, as well as the Scientific and Methodological Center for Monitoring Antibiotic Resistance, created on the initiative of the Federal Agency for Health Care and social development.

The information provided within the project is constantly updated and is available to all users who need information on antibiotic resistance and effective treatment of infectious diseases.

Understanding how relevant the issue of reducing the sensitivity of pathogenic microorganisms and finding a solution to this problem is today is coming gradually. But this is already the first step towards effectively combating the problem called “antibiotic resistance”. And this step is extremely important.

It is important to know!

Natural antibiotics not only do not weaken the body’s defenses, but rather strengthen it. Antibiotics of natural origin have long helped fight various diseases. With the discovery of antibiotics in the 20th century and the large-scale production of synthetic antibacterial drugs, medicine has learned to deal with serious and incurable diseases.

In recent years, nosocomial infections are increasingly caused by gram-negative microorganisms. Microorganisms belonging to the families Enterobacteriaceae and Pseudomonas have acquired the greatest clinical significance. From the family of Enterobacteriaceae, microorganisms of the genera Escherichia, Klebsiella, Proteus, Citrobacter, Enterobacter, Serratia have become often mentioned in the literature as causative agents of postoperative complications, sepsis, and meningitis. Most enterobacteriaceae belong to opportunistic microorganisms, since normally these bacteria (with the exception of the genus Serratia) are obligate or transient representatives of the intestinal microflora, causing infectious processes under certain conditions in weakened patients.

Enteric gram-negative bacilli with resistance to third-generation cephalosporins were first identified in the mid-1980s in Western Europe. Most of these strains (Klebsiella pneumoniae, other Klebsiella species, and Escherichia coli) were resistant to all betalactam antibiotics except cephamycins and carbapenems. The genes encoding information about extended-spectrum beta-lactamases are localized in plasmids, which facilitates the possibility of dissemination of extended-spectrum beta-lactamases among Gram-negative bacteria.

Studies of epidemics of nosocomial infections caused by enterobacteriaceae producing extended-spectrum beta-lactamases indicated that these strains arose in response to the intensive use of third-generation cephalosporins.

The prevalence of extended-spectrum beta-lactamases in Gram-negative bacilli varies among countries and among institutions within a country, often depending on the mix of antibiotics used. In a large US study, 1.3 to 8.6% of clinical E. coli and K. pneumoniae strains were resistant to ceftazidime. Some of the isolates in this study were subjected to more careful study, and it was found that in almost 50% of the strains, resistance was due to the production of extended-spectrum beta-lactamases. Currently, more than 20 extended spectrum beta-lactamases have been identified.

Clinical studies of antimicrobial therapy for infections caused by extended-spectrum beta-lactamase-producing bacteria are virtually absent, and the evidence base for the control of these pathogens consists only of anecdotal case reports and limited retrospective information from epidemiological studies. Data from the treatment of nosocomial epidemics caused by Gram-negative bacteria that produce these enzymes indicate that some infections (eg, urinary tract infections) can be treated with fourth-generation cephalosporins and carbapenems, but severe infections are not always amenable to such treatment.

There has been a sharp increase in the role of Enterobacter as a pathogen. Enterobacter spp. are notorious for their ability to acquire resistance to betalactam antibiotics during therapy, and this is due to inactivating enzymes (beta-lactamases). The emergence of multiresistant strains occurs through two mechanisms. In the first case, the microorganism is exposed to an enzyme inducer (such as a betalactam antibiotic), and increased levels of resistance occur as long as the inducer (antibiotic) is present. In the second case, a spontaneous mutation develops in the microbial cell to a stably derepressed state. Clinically, almost all manifestations of treatment failure are explained by this. Induced beta-lactamases cause the development of multidrug resistance during antibiotic therapy, including the second (cefamandole, cefoxitin) and third (ceftriaxone, ceftazidime) generations of cephalosporins, as well as antipseudomonal penicillins (ticarcillin and piperacillin).

A report of an outbreak of nosocomial infections in a neonatal intensive care unit shows how routine use of broad-spectrum cephalosporins can lead to the emergence of resistant organisms. In this unit, where ampicillin and gentamicin had been the standard empirical treatment for suspected sepsis for 11 years, serious infections due to gentamicin-resistant strains of K. pneumoniae began to appear. Gentamicin was replaced by cefotaxime and the outbreak was eradicated. But a second outbreak of severe infections caused by cefotaxime-resistant E. cloacae occurred 10 weeks later.

Heusser et al. warn about the dangers of empirical use of cephalosporins for infections of the central nervous system caused by gram-negative microorganisms that may have inducible beta-lactamases. In this regard, alternative drugs that are not sensitive to beta-lactamases (trimethoprim/sulfamethoxazole, chloramphenicol, imipenem) are proposed. Combination therapy with the addition of aminoglycosides or other antibiotics may be an acceptable alternative to cephalosporin monotherapy in the treatment of diseases caused by Enterobacter.

In the mid-1980s, Klebsiella infections became a therapeutic problem in France and Germany with the emergence of K. pneumoniae strains resistant to cefotaxime, ceftriaxone, and ceftazidime, which were considered completely stable to the hydrolytic action of beta-lactamases. New varieties of beta-lactamases have been discovered in these bacteria. Highly resistant Klebsiella can cause nosocomial epidemics of wound infections and sepsis.

Pseudomonas is no exception to the development of antibiotic resistance. All strains of P.aeruginosa have a cephalosporinase gene in their genetic code. To protect against antipseudomonal penicillins, plasmids carrying TEM-1 beta-lactamase can be imported. Also, genes for enzymes that hydrolyze antipseudomonal penicillins and cephalosporins are transmitted through plasmids. Aminoglycoside-activating enzymes are also not uncommon. Even amikacin, the most stable of all aminoglycosides, is powerless. There are more and more strains of P. aeruginosa resistant to all aminoglycosides, and this often becomes an insurmountable problem for physicians treating cystic fibrosis and burn patients. P.aeruginosa is increasingly becoming resistant to imipenem.

Haemophilus influenzae - how long will cephalosporins last?

In the 60s and 70s, doctors followed recommendations about the advisability of using ampicillin against H. influenzae. 1974 marked the end of this tradition. Then a plasmid-borne beta-lactamase called TEM was discovered. The frequency of isolation of beta-lactamase-resistant H. influenzae strains varies between 5 and 55%. In Barcelona (Spain), up to 50% of H. influenzae strains are resistant to 5 or more antibiotics, including chloramphenicol and co-trimoxazole. The first report of resistance of this microorganism to cephalosporins, namely to cefuroxime, when an increased MIC of cefuroxime was found, had already appeared in England in early 1992.

Fighting antibiotic resistance in bacteria

There are several ways to overcome bacterial resistance associated with the production of beta-lactamases, including:

Synthesis of antibiotics of new chemical structures that are not subject to the action of beta-lactamases (for example, quinolones), or chemical transformation of known natural structures;

Search for new betalactam antibiotics that are resistant to the hydrolytic action of beta-lactamases (new cephalosporins, monobactams, carbapenems, thienamycin);

Synthesis of beta-lactamase inhibitors.

The use of beta-lactamase inhibitors allows the benefits of known antibiotics to be maintained. Although the idea that beta-lactam structures could inhibit beta-lactamases dates back to 1956, clinical use of inhibitors began only in 1976 after the discovery clavulanic acid. Clavulanic acid acts as a "suicidal" enzyme inhibitor, causing irreversible inhibition of beta-lactamases. This inhibition of beta-lactamases occurs through an acylation reaction, similar to the reaction in which a beta-lactam antibiotic binds to penicillin-binding proteins. Structurally, clavulanic acid is a beta-lactam compound. Without having antimicrobial properties, it irreversibly binds beta-lactamases and disables them.

After the isolation of clavulanic acid, other beta-lactamase inhibitors (sulbactam and tazobactam) were subsequently obtained. In combination with beta-lactam antibiotics (ampicillin, amoxicillin, piperacillin, etc.), they exhibit a wide spectrum of activity against beta-lactamase-producing microorganisms.

Another way to combat antibiotic resistance of microorganisms is to organize monitoring of the prevalence of resistant strains through the creation of an international alert network. Identification of pathogens and determination of their properties, including sensitivity or resistance to antibiotics, must be carried out in all cases, especially when recording a nosocomial infection. The results of such studies must be generalized for each maternity hospital, hospital, microdistrict, city, region, etc. The obtained data on the epidemiological condition should be periodically brought to the attention of the attending physicians. This will allow you to correctly choose when treating a child the drug to which most strains are sensitive, and not prescribe the one to which most strains in a given area or medical institution are resistant.

Limiting the development of resistance of microorganisms to antibacterial drugs can be achieved by following certain rules, including:

Carrying out rationally based antibiotic therapy, including indications, targeted choice taking into account sensitivity and level of resistance, dosage (reduced dosage is dangerous!), duration (in accordance with the picture of the disease and individual condition) - all this requires advanced training of doctors;

Take a reasonable approach to combination therapy, using it strictly according to indications;

Introduction of restrictions on the use of medicines ("barrier policy"), which implies an agreement between clinicians and microbiologists on the use of the drug only in the absence of effectiveness of the drugs already used (creation of a group of reserve antibiotics).

The development of resistance is an inevitable consequence of the widespread clinical use of antimicrobial drugs. The variety of mechanisms by which bacteria acquire resistance to antibiotics is striking. All this requires efforts to find more effective ways to use available drugs aimed at minimizing the development of resistance and identifying the most effective methods for treating infections caused by multidrug-resistant microorganisms.

ANTIBIOTICS AND CHEMOTHERAPY, 1998-N4, pp. 43-49.

LITERATURE

1. Burns J.L. Pediatr Clin North Am 1995; 42: 497-517.

2. Gold H.S., Moellering R.S. New Engl J Med 1996; 335: 1445-1453.

3. New antimicrobial agents approved by the U.S. Food and Drug Administration in 1994. Antimicrob Agents Chemother 1995; 39:1010.

4. Cohen M.L. Science 1992; 257: 1050-1055.

5. Gibbons A. Ibid 1036-1038.

6. Hoppe J.E. Monatsschr Kinderheilk 1995; 143: 108-113.

7. Leggiadro R.J. Curr Probl Pediatr 1993; 23: 315-321.

9. Doern G.V., Brueggemann A., Holley H.P.Jr., Rauch A.M. Antimicrob Agents Chemother 1996; 40: 1208-1213.

10. Klugman K.R. Clin Microbiol Rev 1990; 3: 171-196.

11. Munford R.S., Murphy T.V. J Invest Med 1994; 42: 613-621.

12. Kanra G.Y., Ozen H., Secmeer G. et al. Pediatr Infect Dis J 1995; 14: 490-494.

13. Friedland I.R., Istre G.R. Ibid 1992; 11: 433-435. 14. Jacobs M.R. Clin Infect Dis 1992; 15: 119-127.

15. Schreiber J.R., Jacobs M.R. Pediatr Clinics North Am 1995; 42: 519-537.

16. Bradley J.S., Connor J.D. Pediatr Infect Dis J 1991; 10: 871-873.

17. Catalan M.J., Fernandez M., Vasquez A. et al. Clin Infect Dis 1994; 18: 766-770.

18. Sloas M.M., Barrett F.F., Chesney P.J. et al. Pediatr Infect Dis J 1992; 11: 662-666.

19. Webby P.L., Keller D.S., Cromien J.L. et al. Ibid 1994; 13: 281-286.

20. Mason E.O., Kaplan S.L., Lamberht L.B. et al. Antimicrob Agents Chemother 1992; 36: 1703-1707.

21. Rice L.B., Shlaes D.M. Pediatr Clin Noth Am 1995; 42: 601-618.

22. Christie C., Hammond J., Reising S. et al. J Pediatr 1994; 125: 392-400.

23. Shay D.K., Goldmann D.A., Jarvis W.R. Pediatr Clin North Am 1995; 42: 703-716.

24. Gaines R, Edwards J. Infect Control Hosp Epid 1996; 17: Suppl: 18.

25. Spera R.V., Faber B.F. JAMA 1992; 268:2563-2564.

26. Shay D.K., Maloney S.A., Montecalvo M. et al. J Infect Dis 1995; 172:993-1000.

27. Landman D., Mobarakai N.V., Quale J.M. Antimicrob Agents Chemother 1993; 37: 1904-1906.

28. Shlaes D.M., Etter L., Guttman L. Ibid 1991; 35: 770-776.

29. Centers for Disorder and Prevention 1994; 59: 25758-25770.

30. Hospital Infect Contr Pract Advisory Comm. Infect Control Hosp Epid 1995; 16: 105-113.

31. Jones R.N., Kehrberg E.N., Erwin M.E., Anderson S.C. Diagn Microbiol Infect Dis 1994; 19: 203-215.

32. Veasy G.L., Tani L.Y., Hill H.R. J Pediatr 1994; 124:9-13.

33. Gerber M.A. Pediatr Clin North Am 1995; 42: 539-551.

34. Miyamoto Y., Takizawa K., Matsushima A. et al. Antimicrob Agents Chemother 1978; 13: 399-404.

35. Gerber M.A. Pediatrics 1996; 97: Suppl: Part 2: 971-975.

36. Voss A., Milatovic D., Wallrauch-Schwarz C. et al. Eur J Clin Microbiol Infect Dis 1994; 13:50-55.

37. Moreira B.M., Daum R.S. Pediatr Clin North Am 1995; 42: 619-648. 38. Meyer R. Pädiatr Prax 1994; 46: 739-750.

39. Naquib M.H., Naquib M.T., Flournoy D.J. Chemotherapy 1993; 39: 400-404.

40. Walsh T.J., Standiford H.C., Reboli A.C. et al. Antimicrob Agents Chemother 1993; 37: 1334-1342.

41. Hill R.L.R., Duckworth G.J., Casewell M.W. J Antimicrob Chemother 1988; 22: 377-384.

42. Toltzis P., Blumer J.L. Pediatr Clin North Am 1995; 42: 687-702.

43. Philippon A, Labia R, Jacoby G. Antimicrob Agents Chemother 1989; 33: 1131-1136.

44. Sirot D., De Champs C., Chanal C. et al. Ibid 1991; 35: 1576-1581.

45. Meyer K.S., Urban C., Eagan J.A. et al. Ann Intern Med 1993; 119: 353-358.

46. Bush K., Jacoby G.A., Medeiros A.A. Antimicrob Agents Chemother 1995; 39: 1211-1233.

47. Dever C.A., Dermody T.S. Arch Intern Med 1991; 151:886-895.

48. Bryan C.S., John J.F., Pai M.S. et al. Am J Dis Child 1985; 139: 1086-1089.

49. Heusser M.F., Patterson J.E., Kuritza A.P. et al. Pediatr Infect Dis J 1990; 9: 509-512.

50. Coovadia Y.M., Johnson A.P., Bhana R.H. et al. J Hosp Infect 1992; 22: 197-205.

51. Reish O., Ashkenazi S., Naor N. et al. Ibid 1993; 25: 287-294.

52. Moellering R.S. J Antimicrob Chemother 1993; 31: Suppl A: 1-8.

53. Goldfarb J. Pediatr Clin North Am 1995; 42: 717-735.

54. Schaad U.B. Monatsschr Kinderheilk 1995; 143: 1135-1144.

Antibacterial drugs are an important and often the main component of complex therapy for infectious pathology in obstetric practice; their rational and justified use in most cases determines the effectiveness of the treatment and favorable obstetric and neonatal outcomes.

In Russia, 30 different groups of antibiotics are currently used, and the number of drugs (excluding non-original ones) is approaching 200. In the USA, it has been shown that antibiotics are one of the most frequently prescribed drugs to pregnant women: 3 out of 5 drugs used during pregnancy are antibacterial agents. Although a small number of studies have identified possible negative effects of antimicrobial therapy during pregnancy, the incidence of antimicrobial use during gestation remains largely unknown.

It must be said that the microbiological feature of purulent-inflammatory diseases in obstetrics, gynecology and neonatology is the polymicrobial etiology of these diseases. Among the causative agents of purulent-inflammatory diseases of the urogenital tract in pregnant and postpartum women, opportunistic enterobacteria dominate ( E. coli, Klebsiella spp ., Proteus spp.), often in association with obligate anaerobes of the Bacteroides family - Prevotella spp. and anaerobic cocci. In recent years, the role of enterococci in the etiology of purulent-inflammatory diseases in obstetrics and neonatology has increased, which is apparently due to the resistance of these bacteria to cephalosporins, widely used in obstetric practice. General patterns of the dynamics of the etiological structure of purulent-inflammatory diseases allow us to say that in each hospital there is a certain epidemiological situation, biological characteristics of pathogens and their sensitivity to antibiotics, and therefore local monitoring of the species composition and antibiotic resistance of isolated microorganisms is necessary, which determines the choice of drugs for prevention and treatment of the disease.

The use of antibacterial drugs in obstetric practice has a number of features that should be taken into account for the effective treatment of infectious and inflammatory diseases in pregnant and postpartum women. Antibacterial therapy for purulent-inflammatory diseases in obstetrics and gynecology can be effective only taking into account their clinical picture, etiology, pathogenesis and a number of features that arise in the body of pregnant women and determine the correct choice and adequate use of antibacterial drugs.

During pregnancy, antibacterial therapy should be aimed at eliminating the infection, preventing infection of the fetus and newborn, as well as the development of postpartum purulent-inflammatory diseases. Rational and effective use of antibiotics during pregnancy requires the following conditions:

it is necessary to use drugs only with established safety for use during pregnancy, with known metabolic pathways (US Food and Drug Administration (FDA) criteria);
when prescribing drugs, the duration of pregnancy should be taken into account; it is necessary to be especially careful when prescribing antimicrobial drugs in the first trimester of gestation;
During treatment, careful monitoring of the condition of the mother and fetus is necessary.

Antibacterial drugs for use in obstetric practice should not have either teratogenic or embryotoxic properties; as far as possible, with maximum efficiency, be low-toxic, with a minimum frequency of adverse drug reactions. A number of modern antibiotics fully satisfy these requirements, in particular inhibitor-protected penicillins, cephalosporins and macrolides. Modern antibiotic therapy for individual nosological forms begins with empirical treatment, when antibiotics are administered immediately after diagnosis of the disease, taking into account possible pathogens and their sensitivity to drugs. When choosing a drug for initial therapy, the known literature data on its spectrum of action on microorganisms, pharmacokinetic characteristics, the etiological structure of this inflammatory process, and the structure of antibiotic resistance are taken into account. Before starting therapy, material should be obtained from the patient for microbiological testing.

From the first days of the disease, it is advisable to prescribe an antibiotic or a combination of antibiotics that maximally covers the spectrum of possible pathogens of the disease. To do this, it is necessary to use combinations of synergistically acting antibiotics with a complementary spectrum of action or one drug with a broad spectrum of action. If the disease dynamics are positive, based on the results of a microbiological study, you can switch to drugs with a narrower spectrum of action. After isolating the pathogen and determining its sensitivity to antimicrobial drugs, in the absence of a clinical effect from the started empirical therapy, it is advisable to continue treatment with the drug to which, according to the analysis, the causative agent is sensitive. Targeted monotherapy is often more effective and more cost-effective. A combination of antibacterial drugs is indicated in the treatment of diseases of polymicrobial etiology in order to reduce the possibility of developing antibiotic resistance of certain types of bacteria, to take advantage of the combined action of antibiotics, including reducing the dose of drugs used and their side effects. However, it should be borne in mind that combination therapy is usually less cost-effective than monotherapy.

Antibacterial therapy for purulent-inflammatory diseases in obstetrics and gynecology should be systemic and not local. With systemic treatment, it is possible to create the necessary concentration of antibiotics in the blood and the lesion, maintaining it for the required time. Local use of antibacterial drugs does not allow achieving this effect, which in turn can lead to the selection of resistant strains of bacteria and insufficient effectiveness of local antibiotic therapy.

Antibiotic resistance of microorganisms is one of the most pressing problems of modern medicine. Resistance of microorganisms is distinguished into two types: primary (species), due to the absence of a target for the drug, impermeability of the cell membrane, and the enzymatic activity of the pathogen; and secondary, acquired, when using incorrect doses of the drug, etc.

“If modern medicine... does not fundamentally reconsider its attitude towards the use of antibiotics, sooner or later a post-antibiotic era will come, in which there will be no treatment for many common infectious diseases, and they will again claim many human lives. Surgery, transplantation and many other branches of medicine will become impossible...” These bitter words of the Director General of the World Health Organization (WHO), Dr. Margaret Chan, spoken on World Health Day 2011, ring even more relevant today. Drug-resistant bacteria are rapidly spreading across the planet. More and more essential drugs are no longer effective against bacteria. The arsenal of therapeutic agents is rapidly shrinking. Today, in the European Union, Norway and Iceland, about 25 thousand people die every year from infections caused by resistant bacteria, with the majority of such cases occurring in hospitals. The domestic problem of drug resistance of microorganisms is also regarded as a threat to national security, which is confirmed by the World Economic Forum, which included Russia in the list of countries at global risk, since 83.6% of Russian families take antimicrobial drugs uncontrollably. According to the Russian Ministry of Health, about 16% of Russians currently have antibiotic resistance. At the same time, 46% of the Russian population are convinced that antibiotics kill viruses in the same way as bacteria, and therefore prescribe antibiotics to themselves at the first symptoms of ARVI and influenza. Currently, 60–80% of doctors in the Russian Federation prescribe antibiotics to be on the safe side, without checking whether it will act on a given strain of bacteria in a given patient. We are growing monsters with our own hands - superbugs. At the same time, over the past 30 years, not a single new class of antibiotics has been discovered, but during this same time, the resistance of some pathogens to certain antibiotics has completely excluded the possibility of their use at the present time.

A key reason for the development of resistance is the inappropriate use of antimicrobials, such as:

using drugs unnecessarily or against a disease that the drug does not treat;
taking medications without prescription by a medical specialist;
non-compliance with the prescribed antibiotic regimen (under- or over-use of drugs);
excessive prescription of antibiotics by doctors;
transferring antibiotics to others or using leftover prescription drugs.

Resistance threatens advances in modern medicine. A return to the pre-antibiotic era could result in many infectious diseases becoming untreatable and uncontrollable in the future. Many countries already have government programs to combat antibiotic resistance.

In recent years, the term “superbug” has begun to appear more and more often not only in professional literature, but also in the media for non-medical audiences. We are talking about microorganisms that are resistant to all known antibiotics. As a rule, superbugs are nosocomial strains. The emergence of antibiotic resistance is a natural biological phenomenon that reflects the evolutionary laws of variability and natural selection of Charles Darwin in action, with the only difference being that human activity acts as a “selection” factor, namely the irrational use of antibiotics. Bacterial resistance to antibiotics develops due to mutations or as a result of the acquisition of resistance genes from other bacteria that are already resistant. It turned out that what distinguishes superbugs from others is the presence of the enzyme New Delhi metallo-b-lactamase-1 (NDM1; it was first discovered in New Delhi). The enzyme provides resistance to one of the most effective classes of antibiotics - carbapenems. At least every tenth strain of bacteria carrying the NDM1 enzyme gene has an additional, not yet deciphered set of genes that provide pan-resistance - not a single antibiotic is able to act on this microorganism either bactericidal or even bacteriostatic. The probability of transfer of the NDM1 gene from bacteria to bacteria is high, since it is found in plasmids - additional extrachromosomal carriers of genetic information. These life forms transfer genetic material to each other horizontally, without division: they are connected in pairs by cytoplasmic bridges, along which circular RNAs (plasmids) are transported from one cell to another. The variety of bacteria involved in the “super process” is increasing. These are primarily the causative agents of anaerobic and aerobic wound infections - clostridia, Staphylococcus aureus (in some countries, more than 25% of the strains of this infection are resistant to one or many antibiotics), Klebsiella, Acinetobacter, Pseudomonas. And also the most common pathogen in inflammatory diseases of the urinary tract is Escherichia coli.

In the fight against the problem of resistance, it is very important to follow the rules for prescribing antifungals and antibiotics. Against the backdrop of advancing superbugs, optimistic reports began to appear that ways had been found to combat the invincible enemy. Some rely on bacteriophages, others on coatings with nanopores that attract any bacteria due to the difference in charges, while others persistently search for new antibiotics.

Medical options for overcoming antibiotic resistance include the use of alternative methods of treating infectious processes. In the USA, Europe and Russia, there is a renaissance in targeted therapy of infections using bacteriophages. The advantages of phage therapy are its high specificity, absence of suppression of normal flora, bactericidal effect, including in biofilms, self-replication of bacteriophages in the lesion, i.e. “automatic dosing”, absence of toxic and teratogenic effects, safety during pregnancy, good tolerability and very low chemotherapeutic index. The administration of bacteriophages can be called, without exaggeration, highly specific antibacterial therapy. Historically, the only drugs that suppress bacterial growth were antibacterial viruses - bacteriophages. Bacteriophage preparations have good prospects as an alternative to chemotherapeutic antibacterial therapy. Unlike antibiotics, they have strict selectivity of action, do not suppress normal microflora, stimulate factors of specific and nonspecific immunity, which is especially important in the treatment of chronic inflammatory diseases or bacterial carriage.

Therapeutic and prophylactic bacteriophages contain polyclonal virulent bacteriophages with a wide range of action, which are also active against bacteria resistant to antibiotics. Phage therapy can be successfully combined with the administration of antibiotics.

Thus, in the context of the formation of antimicrobial resistance and the formation of resistant bacterial films, the need for new alternative therapeutic technologies and antimicrobial drugs is becoming increasingly important. The prospects for the use of bacteriophages concern not only antimicrobial therapy, but also high-precision diagnostics, as well as oncology.

But all this should not be reassuring. Bacteria are still smarter, faster and more experienced than us! The surest way is a total change in the system of using antibiotics, tightening control, sharply limiting the availability of drugs without a prescription, and a ban on the non-therapeutic use of antibiotics in agriculture. The United States has adopted the “Getsmart” program, aimed at the judicious use of antibiotics. Canadian program “Do bugs need drugs?” (“Do Microbes Need Medicines?”) reduced the use of antibiotics for respiratory tract infections by almost 20%. In Russia, the problem of widespread and uncontrolled use of antibiotics is still little discussed and does not meet with active opposition from the medical community and government agencies regulating the circulation of medicines.

In the second quarter of 2014, the World Health Organization published a report on global antibiotic resistance. This is one of the first detailed reports in 30 years on such a pressing global issue. It analyzed data from 114 countries, including Russia, on the basis of which it was concluded that antibiotic resistance is now observed in all countries of the world, regardless of their level of welfare and economic development. In 2014, the Russian Federation, for its part, initiated the signing of a document which stipulates that assessing the situation with antibiotic resistance in the country is a national priority. The current situation is of great socio-economic importance and is considered a threat to national security. To overcome this problem, a series of summits of specialists in antibacterial therapy were successfully held in 2014 in Samara, Yekaterinburg, St. Petersburg and Novosibirsk. The Expert Council on Healthcare under the Social Policy Committee of the Federation Council is actively developing strategic directions on this issue. Holding summits of this format will allow us to formalize and consolidate the opinion of leading experts in all regions of the Russian Federation and convey our ideas to the Ministry of Health and the Government of the Russian Federation. The World Health Organization recommends meaningful interventions to prevent infections at the outset, through improved hygiene and access to clean water, infection control in health care settings and vaccination, and the need to develop new medicines and diagnostic tests for microbial resistance, and also the development of national recommendations for the rational use of antibiotics and national regulations to monitor their compliance. An example of the effectiveness of these measures are national companies in European countries. For example, the “Antibiotics: A Smart Approach” program adopted in Thailand is aimed at tightening control over the prescription and dispensing of antibacterial drugs and is addressed to both doctors and patients. Initially, changes to the principles of prescribing antibiotics were developed and implemented, which led to a reduction in their consumption by 18–46%. Next, decentralized networks were created that brought together local and central partners to further expand the program. Australia has adopted a comprehensive package of measures aimed at increasing antibiotic consumption. The key role in curbing antimicrobial resistance, given the decades-long fight against it, now lies with governments and policymakers, as well as the education of health care workers. Many countries implement continuing education programs on antibiotic stewardship.

An analysis of literary sources, reports on the implementation of the tasks of the global strategy and resolutions on antibiotic resistance showed a small amount of information about Russia’s participation in this global process, as evidenced by the lack of research in this area. In this regard, domestic healthcare is faced with the task of creating a reliable surveillance system for the use of antibiotics, organizing a network for monitoring antibiotic resistance, systematically collecting antibiogram data and disseminating the clinical consequences of this phenomenon. Overcoming bacterial resistance to antibiotics requires a systemic, intersectoral approach and proactive action at the national level.

The research was supported by a grant from the Russian Science Foundation (project no. 15–15–00109).

Literature

L. V. Adamyan,Doctor of Medical Sciences, Professor, Academician of the Russian Academy of Sciences
V. N. Kuzmin 1, Doctor of Medical Sciences, Professor
K. N. Arslanyan, Candidate of Medical Sciences
E. I. Kharchenko, Candidate of Medical Sciences
O. N. Loginova, Candidate of Medical Sciences

State Budgetary Institution of Higher Professional Education MGMSU named after. A. I. Evdokimova, Ministry of Health of the Russian Federation, Moscow

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).

Preventative 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 who suffer from the current situation. Antibiotic resistance is already impacting morbidity, mortality, and 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 mortality rate at 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 hope 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 amyloid beta, 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 version 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 using them 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 probability 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 showed 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 Superbug Solutions agent 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 intend 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 establishment of a pan-European clinical trials group.”. According to her, it is already clear to most parties involved in drug development, including industry and scientists, that 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.

On September 19, 2017, a report from the World Health Organization was released on the problem of the dire situation with antibiotics on our planet.

We will try to talk in detail about a problem that cannot be underestimated, because it is a serious threat to human life. This problem is called antibiotic resistance.

According to the World Health Organization, the situation on the planet is fundamentally the same in all countries. That is, antibiotic resistance is developing everywhere and it doesn’t matter whether it’s in the USA or Russia.

When we say antibiotic resistance, we must understand that this is a kind of jargon. Antibiotic resistance refers not only to resistance to antibiotics but also to viral drugs, antifungal drugs and drugs against protozoa.

So where does antibiotic resistance come from?

It's quite simple. People live on a planet whose masters have been microorganisms for three and a half billion years. These organisms are at war with each other, trying to survive. And of course, in the process of evolution, they have developed a colossal number of ways to defend themselves from any type of attack.

The source of resistant microorganisms in our everyday life is medicine and agriculture. Medicine because for 3 generations of people, since 1942, they have been using antibiotics to treat all possible diseases. Of course, there is no way to do without antibiotics for now. Any operation, any treatment of infection requires the prescription of an antibacterial drug. With each use of such a drug, some of the microorganisms die, but the surviving part remains. This is what passes on resistance to the next generation. And over time, superbugs or super-infections appear - microorganisms that are immune to almost any antibiotic. Such superbugs have already appeared in our everyday life and, unfortunately, are reaping a rich harvest of victims.

The second source of the problem is agriculture. Between 80 and 90% of all antibiotics are used for non-medical purposes and non-human use. Antibiotics are practically fed to cattle, otherwise there is no weight gain and the animal gets sick. It cannot be any other way, because we collect millions of heads of livestock in a limited space, keep them in unnatural conditions and feed them with feed that nature does not provide for this type of organism. Antibiotics are a kind of guarantee that Scott will not get sick and will gain the required weight. As a result, tens of thousands of tons of antibiotics end up in nature, and there the selection of resistant strains begins, which come back to us with food.

Of course, not everything is so simple and it’s not just about medicine and agriculture. Tourism and the global economy play a very important role here (when food, some raw materials, fertilizer are transported from one country to another). All this makes it impossible to somehow block the spread of superbugs.

Essentially, we live in one big village, so some superbug that originated in one country becomes a big problem in other countries.

It is worth mentioning such an important reason for the development of antibiotic resistance as the use of drugs without a doctor’s prescription. According to American statistics, approximately 50% of cases of antibiotic use are due to viral infections. That is, any cold and a person begins to use an antibacterial drug. Not only is this ineffective (antibiotics do not work on viruses!!!), but it also leads to the emergence of more resistant types of infections.

And finally, a problem that may seem surprising to many. We have no new antibiotics left. Pharmaceutical companies are simply not interested in developing new antibacterial drugs. Development, as a rule, takes up to 10 years of hard work, a lot of investment, and as a result, even if this drug reaches the market, this does not provide any guarantee that resistance will not appear in a year or two.

In fact, our medical arsenal contains antibiotics developed many years ago. Fundamentally new antibiotics have not appeared in our medical practice for 30 years. What we have are modified and reworked old versions.

And now we are faced with a rather serious situation. We arrogantly set out to compete with a gigantic number of microorganisms that have their own understanding of how to live, how to survive and how to react to the most unexpected circumstances. Moreover, our antibiotics, even the most chemical ones, are not very big news for the microcosm. This is because, for the most part, antibiotics are the experience of the microcosm itself. We observe how microbes fight each other and, drawing conclusions, create an antibacterial drug (for example, penicillin). But even the inventor of the antibiotic himself, Sir Alexander Fleming, warned that the active use of antibiotics will certainly cause the emergence of strains of microorganisms resistant to them.

In connection with the above, simple rules for personal safety when using antibacterial drugs can be derived:

Don't rush to use an antibiotic if you or someone you love coughs.
Use only the antibiotics prescribed by your doctor.
Buy medications only from pharmacies.
If you start taking the drug, be sure to complete the entire course of treatment.
Do not stock up on antibiotics; each medicine has its own expiration date.
Do not share antibiotics with other people. Each person is individually selected for one or another drug.