The uncontrolled and unjustified use of antimicrobial drugs led to the appearance of antibiotic resistance of bacteria. Now this problem has acquired a worldwide scale. International organizations introduce monitoring programs, trying to control the appearance of populations resistant to antimicrobial drugs, such as vanimicine-resistant enterococci, meticulin-resisted golden staphylococci and the like. From the point of view of microbiology, nothing strange happens, because the Universe has its own laws that have helped it exist for many millions of years. This is one of the mechanisms for adapting bacteria for survival.
Other forms of life — viruses have various kinds of survival mechanisms. Almost every now known type of bacteria is a master for one or more viruses (bacteriophages). The first mention of the therapeutic use of phages in veterinary medicine is associated with the name of Felix d’erell. In the spring of 1919, in France there was an outbreak of bird typhoid at chickens. He examined several dead carcasses, highlighted and identified the pathogen — Salmonella Gallinam. He also secreted bacteriophages from dead chickens and experienced their effectiveness in the prevention and treatment of a disease caused by Salmonella Gallinam in six experimentally infected birds. As a result, the use of phages warned the death of a bird from a bacterial infection, while two control chicken (which did not receive bacteriophage) died from a single injection of the pathogen. The results of this test became the basis for large -scale research.
Thus, the first biological model that was used to study the therapeutic effect of bacteriophages was salmonellosis and chickens, later scientific research was expanded to diseases such as pasteurellosis, escherchiosis, vibriosis, strepto — staphylocosis and the like.
The use of bacteriophages
Bacteria phages are common in almost all ecosystems: in the soil, water, air, feces of humans and animals, industrial and domestic drains and the like. They are one of the elements of these systems, respectively, the spectrum of bacterial pathogens, which can be targets of phages, are quite wide. This makes them a significant alternative to antibiotics and an ideal “weapon” against microbes.
The scientific discussion regarding the effectiveness of phagish therapy was unfolded immediately after the application for the possibility of the prevention and treatment of bacterial infections using bacteria viruses. Some scientists considered bacteriophages as live enzymes, some claimed to have antibacterial substances. Indeed, the first drugs were somewhat unfinished, because they contained the remains of nutrient media, metabolism products and the remnants of bacterial cells. Metabolism products may contain antimicrobials, and fragments of lysed bacterial cells are lipopolysaccharides that activate the immune system, which smooth out the effect of faculi therapy. Therefore, technologies for obtaining highly purified phagic drugs were developed. Phagoprusias are divided into species -specific (act only on a certain type of microorganisms) and phages, which affect several types of microorganisms.
Definition of effectiveness
Discussions regarding the effectiveness of these drugs are still continuing. That is why one of the most common universal phagic drugs was tested, which, according to the instructions for use, should act against microorganisms of seven species. Chose four of them and picked up the reference representatives of these births.
As a result of the studies, it was found that in all cases in Wednesdays with the addition of a universal fabric drug, the concentration of bacterial cells was much less, but the complete death of microorganisms and enlightenment of the medium did not occur.
Therefore, the studied drug did not show one hundred percent effectiveness with test microorganisms. However, this experience requires further research, since it is considered necessary to study the mechanism of action of phages at the molecular genetic level — observing the replacement of the phage of the bacterial genome and the exclusion of the possibility of the formation of lysogenic populations of bacteria treated with a universal phagish drug.
In any case, this experience only confirms the possibility of using bacteriophages as an alternative to antibiotics and gives the basis for their use in the food and processing industry to prevent contamination of foods by pathogens of food toxicoinfections. After all, the contamination of poultry products with salmonella, leaferii, campilobacteria, Jersinius and esherchia is a problem not only in Russia, but throughout the world.
It should be noted that according to scientific publications, domestic scientists have already conducted research, which were aimed at studying the possibility of decontamination of poultry products from Salmonella Gallinam Pullom using bacteriophages. As a result of the studies, it was found that the meat, which was treated with a solution of the phage, after 12 hours was 92.3% less contaminated by salmonella (compared to control), and after 24 hours — by 97.4%, which was almost 90, 9 times less level of contamination of the control group meat.
Such results are very encouraging, but, unfortunately, so far there is no way to reproduce this experience, because the researchers have not deposited the phage they use in any of the depository of Russia.
The mechanism of action of bacteriophages
Of course, a clear understanding is necessary that bacteriophages are not replacing antibiotics, but are an alternative. Since they have a slightly different mechanism of action and effect on microbial biocenosis. First of all, the high specificity of bacteriophages should be emphasized: their action is aimed against a certain type of microorganism — other species remain unchanged. At the same time, the action of antibiotics applies to both pathogenic and bond (normoflora) microorganisms, which inevitably causes dysbiosis. Indeed, in the case of the “destruction” of a certain type of microorganism, a free ecological niche occurs, which can potentially become a “place of residence” for other, more strict, microorganisms. That is why the doctor of veterinary medicine must clearly understand the microbiological processes occurring in the poultry and use probiotic drugs after the course of antibiotics. The phenomenon of vidospecifications of bacteriophages allows minimizing the size of the ecological niche, which is formed after their use and, accordingly, to restore and stabilize the populations of bond bacteria faster.
The development of secondary resistance for bacteriophages is not characteristic, since the mechanism of their action is to include its (viral) DNA in the bacteria genome with its subsequent lysis (the action of virulent phages). When using antibiotics and other chemotherapeutic drugs, the development of resistance to them is a fairly common phenomenon and ranges from 60-90% of cases.
The ability of antibacterial drugs to penetrate the body tissues ranges from high to very low, while in bacteriophages this ability is very high. This contributes to a high concentration of phages in the place of the infectious process, their number increases by self -cutting, and they are eliminated from macroorganism after the complete elimination of an infectious agent. The concentration of antibiotics in the foci of infection depends on many factors: the bioavailability of the drug, the type of microorganism and its localization in macroorganism, the duration of the infectious process.
In the case of prescribing antibiotic therapy, the rational combination of drugs depends on their class and can go through the type of summation, potention, etc. D. Depending on the mechanism of action on the bacterial cell. In the case of phages — combination always takes place according to the type of potential, regardless of the class of the drug.
The side effects of chemotherapeutic agents are mainly known and manifested in the form of allergic reactions, toxic effects on the tissue and organs of macroorganism, and also causes dysbiotic phenomena. At the same time, the only now-known side effect of bacteriophageotherapy in isolated cases is allergic reactions that occur due to the massive destruction of bacterial cells and the release of phage particles.
The preventive use of antibiotics, from the point of view of microbiology, is irrational. However, this does not apply to the use of phages.
The process of creating new antibacterial drugs requires several to several decades. The drug based on bacteriophages can be created and tested during the year, provided that there is an active and specific virulent facet.
So, the era of antibiotics is gradually fading away, scientists around the world are in active search for their adequate and effective replacement, and bacteria viruses are one of such means that can successfully cope with this task. Due to certain circumstances, this direction has slowly developed for a long time, but now veterinary medicine has come to the need to intensify research.