We thought that after the discovery of penicillin, we would no longer be afraid of germs. But we were wrong. It's like a real war. Man invents new means of defense against bacterial attacks. In response, microorganisms improve weapons, train fighters, use camouflage and sabotage groups. The problem of antibiotic resistant infections has become so serious that a special session of the UN General Assembly was recently devoted to it. According to the data presented, at least 700,000 people die every year due to drug-resistant infections. Indestructible microbes are on a par with global climate change and other problems on a planetary scale.
Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium that is resistant to many antibiotics (particularly penicillins). It causes severe pneumonia and sepsis. Of course, in reality, the microbe does not look quite like this: the evil grin is the artist's fantasy. Photo: "Schrödinger's Cat"
In the winter of 2003, Ricky Lannetty, a successful 21-year-old soccer player, developed a cough and then nausea. A few days later, Ricky's mother forced her son to see a doctor. All the symptoms pointed to the flu virus, so he did not prescribe antibiotics to Ricky, because they kill bacteria, not viruses. But the disease did not go away, and the mother took Ricky to a local hospital - by this time, the young man's kidneys were already failing. He was prescribed two strong antibiotics: cefepime and vancomycin. But less than a day later, Ricky died. Tests revealed the killer was methicillin-resistant Staphylococcus aureus (MRSA), a toxic bacterium that is resistant to multiple antibiotics.
Strains such as MRSA are now referred to as supermicrobes. Like horror heroes, they mutate and acquire superpowers that allow them to resist their enemies - antibiotics.
End of the era of antibiotics
In 1928, after returning from vacation, the British biologist Alexander Fleming discovered that the Petri dishes with bacterial cultures he left inadvertently were overgrown with mold. A normal person would take it and throw it away, but Fleming began to study what happened to microorganisms. And I found out that in those places where there is mold, there are no staphylococcus bacteria. This is how penicillin was discovered.
Fleming wrote: "When I woke up on September 28, 1928, I certainly did not plan to revolutionize medicine by discovering the world's first antibiotic, but I believe that is exactly what I did." The British biologist for the discovery of penicillin in 1945 received the Nobel Prize in Physiology or Medicine (together with Howard Flory and Ernst Cheyne, who developed the technology for purifying the substance).
Modern man is accustomed to the fact that antibiotics are affordable and reliable helpers in the fight against infectious diseases. No one panics about a sore throat or a scratch on their arm. Although two hundred years ago, this could lead to serious health problems and even death. The 20th century was the era of antibiotics. Together with vaccination, they saved millions, maybe even billions of people who would certainly have died from infections. Vaccines, thank God, are working properly (doctors do not seriously consider the social movement of vaccine fighters). But the era of antibiotics seems to be coming to an end. The enemy is coming.
How supermicrobes are born
Single-celled creatures began to explore the planet first (3.5 billion years ago) - and continuously fought with each other. Then multicellular organisms appeared: plants, arthropods, fish ... Those who retained the unicellular status thought: what if we put an end to civil strife and start capturing new territories? Inside the multicellular is safe and there is plenty of food. Attack! Microbes moved from one creature to another until they got to a person. True, if some bacteria were "good" and helped the owner, then others only caused harm.
People opposed these "bad" microbes blindly: they introduced quarantine and practiced bloodletting (for a long time this was the only way to fight all diseases). And only in the XIX century it became clear that the enemy has a face. Hands began to be washed, hospitals and surgical instruments began to be treated with disinfectants. After the discovery of antibiotics, it seemed that mankind had received a reliable means of fighting infections. But bacteria and other single-celled organisms did not want to leave the warm place and began to acquire resistance to drugs.
A supermicrobe can resist an antibiotic in different ways. For example, it is able to produce enzymes that degrade the drug. Sometimes he is just lucky: as a result of mutations, his membrane becomes invulnerable - a shell on which drugs used to deal a crushing blow. Resistant bacteria are born in different ways. Sometimes, as a result of horizontal gene transfer, bacteria harmful to humans borrow drug defenses from beneficial ones.
Another, more realistic image of methicillin-resistant Staphylococcus aureus (MRSA). Every year it spreads more widely, especially inside hospitals and among people with weakened immune systems. According to some reports, in the United States, this microbe kills about 18 thousand people every year (the exact number of sick and dead is still impossible to determine). Photo: "Schrödinger's Cat"
Sometimes a person himself turns the body into a training center for killer bacteria. Let's say we treat pneumonia with antibiotics. The doctor prescribed: you need to take the medicine for ten days. But on the fifth, everything goes away and we decide that it’s enough to poison the body with all sorts of filth and stop taking it. At this point, we have already killed some of the bacteria that are least resistant to the drug. But the strongest remained alive and were able to reproduce. So, under our strict guidance, natural selection began to work.
"Drug resistance is a natural phenomenon of evolution. Under the influence of antimicrobials, the most sensitive microorganisms die, while resistant ones remain. And they begin to multiply, passing resistance to their offspring, and in some cases to other microorganisms," explains the World Health Organization.
Single-celled attack
In the fall of 2016, a meeting of the UN General Assembly is taking place in New York, which is attended by representatives of 193 countries, that is, in fact, the entire planet. Usually, issues of war and peace are discussed here. But now we are not talking about Syria, but about microbes that have developed resistance to drugs.
The forecast is grim. “Infections are becoming increasingly difficult for patients to cure as the level of resistance of pathogenic microorganisms to antibiotics and, even worse, reserve antibiotics, is steadily increasing. Combined with the extremely slow development of new antibiotics, this increases the likelihood that respiratory and skin infections, urinary infections paths, blood flow can become incurable, and therefore fatal," explains Dr. Nedret Emiroglu from the WHO European Office.
I would definitely add malaria and tuberculosis to this list of diseases. In recent years, it has become increasingly difficult to fight them, as the pathogens have become resistant to drugs, Yury Vengerov specifies.
Keiji Fukuda, Assistant Director General of WHO for Health Security, says about the same thing: "Antibiotics are losing their effectiveness, so that common infections and minor injuries that have been cured for many decades can now kill again."
Model of a bacteriophage that infects a microbe. These viruses invade bacteria and cause their lysis, that is, dissolution. Although bacteriophages were discovered at the beginning of the 20th century, they are only now being included in official medical reference books. Photo: "Schrödinger's Cat"
Bacteria began to resist especially zealously when antibiotics began to be used in large quantities in hospitals and in agriculture, assures biochemist Konstantin Miroshnikov (Doctor of Chemistry, Head of the Laboratory of Molecular Bioengineering of the Institute of Bioorganic Chemistry named after Academicians M.M. Shemyakin and Yu.A. Ovchinnikov RAS). - For example, to stop diseases in chickens, farmers use tens of thousands of tons of antibiotics. Often for prevention, which allows bacteria to get to know the enemy better, get used to it and develop resistance. Now the use of antibiotics began to be limited by law. I believe that public discussion of such issues and further tightening of the law will slow down the growth of resistant bacteria. But they won't be stopped.
The possibilities of creating new antibiotics are almost exhausted, and the old ones are failing. At some point, we will be powerless against infections, - Yuri Vengerov admits. - It is also important to understand that antibiotics turn into a medicine only when there is a dose that can kill microbes, but not harm a person. The probability of finding such substances is less and less.
Did the enemy win?
The World Health Organization periodically publishes panic statements: they say that first-line antibiotics are no longer effective, more modern ones are also close to capitulation, and fundamentally new drugs have not yet appeared. Is the war lost?
There are two ways to fight microbes, - says biologist Denis Kuzmin (PhD in Biology, employee of the Educational and Scientific Center of the Institute of Bioorganic Chemistry of the Russian Academy of Sciences). - First, to look for new antibiotics that affect specific organisms and targets, because it is the "large caliber" antibiotics that affect a whole bunch of bacteria at once that cause an accelerated growth of resistance. For example, it is possible to design medicines that begin to act only when a bacterium with a certain metabolism is ingested. Moreover, manufacturers of antibiotics - producing microbes - need to be sought in new places, more actively use natural sources, unique geographical and ecological zones of their habitat. Secondly, new technologies for obtaining and cultivating antibiotic producers should be developed.
These two methods are already being implemented. New methods for finding and testing antibiotics are being developed. Microorganisms that can become a new generation of weapons are being searched everywhere: in rotting plant and animal remains, silt, lakes and rivers, air ... For example, scientists managed to isolate an antimicrobial substance from the mucus that forms on the skin of a frog. Remember the ancient tradition of putting a frog in a jug of milk so that it doesn't turn sour? Now this mechanism has been studied and they are trying to bring it to medical technology.
Another example. More recently, Russian scientists from the Research Institute for the Discovery of New Antibiotics. G.F. Gause researched the inhabitants of edible mushrooms and found several potential sources of new medicines.
Scientists from Novosibirsk working in the Russian-American laboratory of biomedical chemistry of the ICBFM SB RAS went the other way. They managed to develop a new class of substances - phosphorylguanidines (it is difficult to pronounce, and it is not easy to write down). These are artificial analogues of nucleic acids (more precisely, their fragments), which easily penetrate the cell and interact with its DNA and RNA. Such fragments can be created for each specific pathogen based on the analysis of its genome. The project is headed by the American Sidney Altman (Nobel Prize winner in chemistry in 1989 (together with Thomas Check). Yale University professor. In 2013 he received a Russian mega-grant and began working at the Institute of Chemical Biology and Fundamental Medicine of the Siberian Branch of the Russian Academy of Sciences).
But the most popular areas for finding drugs against infections are bacteriophages and antimicrobial peptides.
Allies from the puddle
From a bird's eye view, the IBCh RAS building looks like a DNA double helix. And just outside the gate stands an incomprehensible sculpture. The plate explains that this is a complex of the antibiotic valinomycin with a potassium ion in the middle. Fifty years ago, the staff of the institute understood how metal ions bind to each other and how they then pass through the cell membrane thanks to ionophores.
Now the IBCh is also working on another topic - bacteriophages. These are special viruses that selectively attack bacteria. The head of the laboratory of molecular bioengineering, Konstantin Miroshnikov, affectionately calls his bacteriophage wards animals.
Phages are good and at the same time bad because they act on a specific pathogen. On the one hand, we aim only at those microbes that interfere with life, and do not disturb the rest, and on the other hand, it takes time to find the right phage, which is usually not enough, - the head of the laboratory smiles.
Both bacteria and bacteriophages are in every puddle. They are constantly fighting each other, but for millions of years, neither side can defeat the other. If a person wants to overcome bacteria that attack his body or potatoes in a warehouse, more of the corresponding bacteriophages must be delivered to the breeding site of bacteria. Here is a metaphor, for example: when they developed the coast of Golden Sands in Bulgaria, there were a lot of snakes, then they brought a lot of hedgehogs and they quickly shifted the balance of the fauna.
Two years ago, we began to cooperate with the Rogachevo agricultural park near Dmitrov. The general director of the organization, Alexander Chuenko, is a former electronics engineer and an enlightened capitalist, not alien to the scientific approach, - says Konstantin. - The potato crop was eaten by pectolytic bacteria - soft rot that lives in warehouses. If the problem is not solved, potatoes quickly turn into tons of smelly slurry. Treatment of potatoes with phages at least sharply slows down the development of infection - the product retains its taste and presentation longer both in storage and on store shelves. At the same time, the phages attacked putrefactive microbes and biodegraded - they disintegrated into DNA particles, proteins and went to feed other microorganisms. After successful tests, the management of several large agricultural complexes became interested in such bioprotection of the crop.
How did you manage to find the right bacteriophages and turn them into an antidote? I ask, glancing at the toy phage on top of the stack of books.
There is a classic double agar method to look for. First, lay a kind of lawn of bacteria on the first layer of agar in a Petri dish, pour water from the puddle on top and cover with a second layer of agar. After some time, a clean spot appears on this muddy lawn, which means that the phage ate the bacterium. We isolate the phage and study it.
Miroshnikov's laboratory, together with Russian and foreign colleagues, received a grant from the Russian Science Foundation for the study and diagnosis of potato pathogens. There is something to work on: plant bacteria have been studied much worse than human ones. However, with our body, too, a lot of unclear. According to scientists, this is not how doctors examine a person: all tests and examinations are tailored for antibiotics, and other methods are needed for phage therapy.
Phage therapy is not a medicine in the current sense, but rather a comprehensive service that includes rapid diagnosis and selection of the right remedy against a specific pathogen. In Russia, phage preparations are included in the list of drugs, but are not mentioned in the guidelines for therapists. So doctors who are in the subject are forced to use phages at their own peril and risk. And in Poland, for example, the law says that if a patient cannot be cured by traditional evidence-based medicine, you can use at least dancing with a tambourine, even homeopathy, even phage therapy. And at the Hirschfeld Institute in Wroclaw, phages are used as personalized medical care. And with great success, even in the case of advanced purulent infections. The use of phages is a scientifically substantiated and biologically understandable, although not a banal method, Miroshnikov sums up.
Peptides are a family of substances composed of amino acid residues. Recently, scientists are increasingly considering peptides as the basis for future drugs. It's not just about antibiotics. For example, at Moscow State University. M.V. Lomonosov and the Research Institute of Molecular Genetics of the Russian Academy of Sciences created a peptide drug that normalizes brain function, improves memory, attention and resistance to stress. Photo: "Schrödinger's Cat"
And here is the news from the science city of Pushchino. Scientists from the branch of the IBCh RAS, the Institute of Theoretical and Experimental Biophysics of the RAS and the Institute of Biochemistry and Physiology of Microorganisms. G.K. Scriabin RAS studied how the enzyme of the bacteriophage T5 acts on E. coli. That is, they worked not with the bacteriophages themselves, but with their enzyme proteins. These enzymes destroy the cell walls of bacteria - they begin to dissolve and die. But some microbes have a strong outer membrane, and this method does not work on them. In Pushchino, they decided to attract substances that increase the permeability of the membrane to help the enzyme. As a result of experiments on E. coli cell cultures, scientists found that together the enzyme and the agent destroy bacteria much more effectively than individually. The number of surviving cells was reduced by almost a million times relative to the control experiment. Cheap common antiseptics such as chlorhexidine were used as an assistant substance, and in very low concentrations.
Phages can be used not only as a medicine, but also as a means of increasing the effectiveness of vaccinations.
As part of a project supported by the Ministry of Education and Science of Russia, we are going to use bacteriophage proteins to enhance the immunogenic properties of an artificial antigen, - says microbiologist Andrey Letarov (Doctor of Biology, Head of the Laboratory of Microorganism Viruses at the S.N. Vinogradsky Institute of Microbiology, Federal Research Center of Biotechnology of the Russian Academy of Sciences ). - For this, antigen fragments are linked by genetic engineering with some bacteriophage proteins that are able to assemble into ordered structures, such as tubes or spheres.
As the scientist explains, such structures with their properties resemble particles of pathogenic viruses, although in fact they do not pose any danger to humans and animals. The immune system is much more likely to recognize such virus-like particles and quickly develops an antibody response. This is the way to create an improved vaccine that, in addition to traditional long-term protection, will provide a rapid protective effect to prevent the spread of the disease in the focus of infection.
Worm and pig immunity
Pavel Panteleev, a junior researcher at the Educational and Scientific Center of the Institute of Bioorganic Chemistry, RAS (PhD in Chemistry) likes to ride a bicycle in the mountains. He also likes to study marine invertebrates, more precisely, their antimicrobial peptides, which fight bacteria in living organisms on a daily basis. Peptides are the younger brothers of proteins: they also consist of amino acids, only there are no more than fifty of them, and there are hundreds and thousands in proteins.
At the beginning of each article about peptides, something like this is written: "There is an urgent need to create new antibiotics, because the old ones no longer work due to resistance. And antimicrobial peptides have a wonderful property - resistance from bacteria is developed to them with great difficulty." The educational and scientific center where I work is looking for peptides that would allow us to resist pathogenic microorganisms, says Pavel.
Today, more than 800 such peptides are known, but all of them do not work in humans. Peptide-based drugs fail clinical trials over and over again: it is not possible to find stable structures that would go to the right place in the right amount and not cause side effects. They tend to accumulate in the body: for example, they can kill the infection, but not go out with urine, but remain in the kidneys.
We are studying marine annelids, says Pavel. - Together with colleagues from the Institute of Experimental Medicine, we isolated two peptides from the worms Arenicola marina (marine sandworm) and studied them. When I was a graduate student, we still went to the White Sea for worms, but no new peptides were found in them. Of course, this may be due to the imperfection of the search technique, but, most likely, this worm really has only two peptides, and this is enough to defend itself against pathogens.
Why worms, are they easier to study?
The fact is that there is a concept according to which the innate immunity system of ancient invertebrates should be very strong, because many of them live in not the most favorable environmental conditions and still exist. Now one of the objects of my research are horseshoe crab peptides.
Pavel takes out his phone and shows something with a tortoise shell and a bunch of disgusting crab legs. This can only be seen in a horror movie or in a bad dream.
Bacteriophage. Its real height is about 200 nanometers. The thickening at the top is called the head. It contains nucleic acid. Photo: "Schrödinger's Cat"
However, it does not matter what you study, worms, horseshoe crabs or pigs, Pavel continues. - In all organisms, you will examine the same tissues and cells where the peptides are located. For example, blood cells are neutrophils in mammals or hemocytes in invertebrates. While it is not known why, one can only put forward hypotheses, including playful ones. The pig is not a particularly clean animal, so it needs more protectors to prevent the bacteria from its mud bath from infecting the body with something. But there is also a universal answer: in each case, there are as many peptides as necessary to protect the body.
Why are peptides better than antibiotics?
Peptides are cleverly arranged. Unlike antibiotics, which, as a rule, act on a specific molecular target, peptides are integrated into the bacterial cell wall and form special structures in it. Eventually, the cell membrane collapses under the weight of the peptides, the invaders get inside, and the cell itself explodes and dies. In addition, peptides act quickly, and the evolution of the membrane structure is a very disadvantageous and complicated process for bacteria. Under such conditions, the likelihood of developing resistance to peptides is minimized. By the way, in our laboratory, peptides are studied not only from animals, but also from plants, for example, protective compounds of a protein-peptide nature from lentils and dill. On the basis of selected natural samples, we create something interesting. The resulting substance may well be a hybrid - something between a peptide of a worm and a horseshoe crab, Pavel assures.
P.S.
Hopefully, in five, ten or twenty years, a new era of microbial control will come. Bacteria are cunning creatures and, perhaps, will create even more powerful means of defense and attack in response. But science will not stand still, so that in this arms race victory will still remain with man.
Man and bacteria. Metaphors
Friends
Staff members- Bacteria that live in our body. According to some estimates, their total mass is from one to three kilograms, and by number they are more than human cells. They can be employed in manufacturing (vitamin production), the processing industry (digesting food), and the military (in our gut, these bacteria suppress the growth of their pathogenic counterparts).
Guest food experts- lactic acid and other bacteria are used to produce cheese, kefir, yogurt, bread, sauerkraut and other products.
Double agents Basically, they are enemies. But they managed to recruit and force them to work for the needs of our defense. We are talking about vaccinations, that is, the introduction of weakened variants of bacteria into the body.
Adopted children- these are no longer bacteria, but parts of our cells - mitochondria. Once they were independent organisms, but, having penetrated the cell membrane, they lost their independence and since then have been regularly providing us with energy.
POW Workers- genetically modified bacteria are used to produce medicines (including antibiotics) and many other useful substances.
Enemies
Fifth column- some bacteria that live in our body or on the skin, in a normal situation, can be quite harmless. But when the body is weakened, they cunningly raise an uprising and go on the offensive. They are also called opportunistic pathogens.
defensive fortresses- colonies of bacteria that cover themselves with mucus and films that protect against the action of drugs.
Armored infantry- among bacteria resistant to antibiotics, there are those that can make their outer shells impenetrable to drug molecules. The power of the infantry is hidden in the lipopolysaccharide layer. After the bacteria die, this layer of fat and sugar enters the bloodstream and can cause inflammation or even septic shock.
Training bases- situations in which the most resistant and dangerous strains survive. Such a training base for bacterial special forces can serve as a human body that violates the course of taking antibiotics.
Chemical weapon- some bacteria have learned to produce substances that decompose drugs, depriving them of their healing properties. For example, enzymes from the beta-lactamase group block the action of antibiotics from the group of penicillins and cephalosporins.
Disguise- microbes that change the outer shell and protein composition so that drugs "do not notice" them.
Trojan horse- some bacteria use special tricks to defeat the enemy. For example, the causative agent of tuberculosis (Mycobacterium tuberculosis) is able to get inside macrophages - immune cells that trap and digest wandering pathogenic bacteria.
super soldiers- these all-powerful bacteria are not afraid of almost no drugs.
Ten Commandments of Antibacterial Behavior
1. Get vaccinated in a timely manner.
2. Use antimicrobials only when prescribed by a licensed physician.
3. Once again: do not self-medicate with antibiotics!
4. Remember that antibiotics do not help against viruses. Treating them with influenza and many types of "colds" is not only useless, but also harmful. It seems that this is done at school, but during the VTsIOM study, the question "Do you agree with the statement that antibiotics kill viruses as well as bacteria?" 46% of respondents answered "yes".
5. Take the medicine exactly in those doses and for as many days as prescribed by the doctor. Do not stop taking even when you feel healthy. “If you don’t complete the treatment, there is a risk that the antibiotics won’t kill all the bacteria that caused your illness, that these bacteria will mutate and become resistant. This does not happen in every case - the problem is that we don’t know who may end treatment prematurely and without consequences," WHO experts admit.
6. Never share antibiotics.
7. Do not use previously prescribed and remaining after taking antibiotics.
8. Wash your hands. Drink only clean water.
9. Use protective equipment during sexual intercourse.
10. Avoid close contact with patients. If you yourself get sick, show nobility - do not try to infect your classmates, fellow students or colleagues. I mean, stay at home.