The bulk of the intestinal microflora of adults are. Normal microflora. What is normal intestinal flora

"Second brain" - this is what neurophysiologists call the digestive organs. They proved the direct connection and constant exchange of information between the intestines and the brain, as well as the existence of an autonomous (separate) mini-nervous system in the digestive tract. This fact proves the direct dependence of the state of physical health and psychological comfort of a person on the good work of his intestines. In turn, the normal functioning of the intestine depends on the balance of the microflora inhabiting it.

Members of the intestinal microflora

Microorganisms in the intestine can be represented by both beneficial and pathogenic species:

1. Useful microflora is represented by a wide variety of bacteria (several hundred species). The most studied and necessary are: lactobacilli, bifidobacteria, Escherichia coli.

2. Pathogenic microflora, which can normally be present in the intestine, but should not exceed 1%, is represented by cocci, fungi, yeast, clostridia, protozoa and other species. The predominance of such flora is most often manifested by rumbling, or disturbances in the stool, and from stool.

The role of beneficial microflora in the body

Intestinal microorganisms under normal conditions of life perform the most important functions:

Digestion

The bacteria covering the walls of the intestines produce a large number of enzymes and active substances (for example, lactic and acetic acids) necessary for the final digestion of food and the absorption of nutrients (vitamins, minerals) and water from it. The microflora breaks down and assimilates amino acids, fatty acids, carbohydrates, thereby participating in the metabolism.

Immunity

The main number of cells responsible for immune defense is concentrated in the intestine, since the synthesis of compounds that make up immunoglobulins occurs in it. In addition, bacteria are able to synthesize antibiotic substances that are involved in the local defense of the body in the form of suppression of harmful and putrefactive microbes, protozoa and worms, as well as substances that stimulate the protective function of the blood.

Synthesis of necessary substances

Scientists have proven that the microflora, in a healthy intestine, provides the body with almost all types of vitamins (B-group, including the mythical B12, K, H, PP, C and others) and amino acids (including essential ones).

Body detoxification

Representatives of a healthy microflora are able to participate in the neutralization of endo- and exotoxins and their removal.

Microorganisms directly affect intestinal motility, and indirectly - on the condition of the skin, hair, blood vessels, bones, joints and other body systems. Based on the considered main functions carried out by the microorganisms of a healthy intestine, the role of microflora in the balance of the whole organism is truly enormous and multifaceted, and, unfortunately, is often underestimated neither by doctors nor by people without special knowledge. education.

Factors that are detrimental to microflora and lead to imbalance

1. Wrong eating style. Food harms beneficial intestinal microorganisms:

• over-processed (refined, boiled, fried),
• with a large percentage of confectionery, flour and starch products,
• canned, smoked, saturated with artificial additives,
• high in animal protein and fat,
• carbonated drinks, coffee, tea,
• hot and chilled, spicy and salty, as well as: foods with a small amount of fiber from plants, fruits and vegetables,
• binge eating,
• insufficient drinking water.

2. Stress, emotional tension, as well as lack of physical activity - make it difficult for the intestines to work in the form of constipation or diarrhea, disrupting the composition of the microflora.

3. They deplete the beneficial microflora, causing dysbacteriosis, and the abuse of alcohol-containing drinks, smoking, treatment with antibiotics and most chemicals.

All of these factors, killing and weakening the beneficial intestinal microflora (as well as skin, mucous membranes), increase the unpleasant processes of fermentation and decay in the body, thereby causing most diseases (for example, cardiovascular and oncology), as well as premature aging.

Obviously, to maintain a balance of intestinal microflora, it is necessary to adhere to healthy life principles in general, and for most people - to radically change their habits.

The most ancient and effective method of healing is fasting. There are many techniques that differ in duration and methods of entry and exit from fasting. The safest, but no less effective, is a weekly one-day refusal of food. In the process of such a rest, the balance of microflora is naturally restored, and the body launches self-purification mechanisms.

In contact with

Classmates

The intestinal microflora in a broad sense is a combination of various microorganisms. In the human intestine, all microorganisms are in symbiosis with each other. On average, about 500 species of various microorganisms live in the human intestine, both beneficial bacteria (which help digest food and give vitamins and complete protein to a person) and harmful bacteria (which feed on fermentation products and produce decay products).

Modification of the quantitative ratio and species composition of the normal microflora of an organ, mainly the intestine, accompanied by the development of microbes atypical for it, is called dysbacteriosis. Most often this happens due to malnutrition.

But a violation of the microflora can occur not only due to malnutrition, but also due to the intake of various antibiotics. In any case, there is a violation of the microflora.

Normal intestinal microflora

The main representatives of the mandatory microflora of the human colon are bifidobacteria, bacteriods, lactobacilli, E. coli and enterococci. They make up 99% of all microbes, only 1% of the total number of microorganisms belongs to opportunistic bacteria such as staphylococci, proteus, clostridia, Pseudomonas aeruginosa and others. Pathogenic microflora in the normal state of the intestine should not be, the normal intestinal microflora in humans begins to develop already during the passage of the fetus through the birth canal. Its formation is completely completed by the age of 7-13.

What is the function of the normal intestinal microflora? First of all, protective. So, bifidobacteria secrete organic acids that inhibit the growth and reproduction of pathogenic and putrefactive bacteria. Lactobacilli have antibacterial activity due to their ability to form lactic acid, lysozyme and other antibiotic substances. Colibacteria antagonistically act on pathogenic flora through immune mechanisms. In addition, on the surface of the cells of the intestinal epithelium, representatives of the normal microflora form the so-called "microbial turf", which mechanically protects the intestine from the penetration of pathogenic microbes.

In addition to the protective function, normal microorganisms of the large intestine are involved in the metabolism of the macroorganism. They synthesize amino acids, proteins, many vitamins, take part in cholesterol metabolism. Lactobacilli synthesize enzymes that break down milk proteins, as well as the enzyme histaminase, thereby performing a desensitizing function in the body. The beneficial microflora of the colon promotes the absorption of calcium, iron, vitamin D, preventing the development of the oncological process.

Causes of violation of microflora

There are a number of social factors that disrupt the microflora. This is primarily acute and chronic stress. Such “critical” conditions for human health affect both children and adults. For example, a child goes to the first grade, respectively, he worries and worries. The process of adaptation in a new team is often accompanied by health problems. In addition, during the learning process, tests, exams, and workload can cause stress.

Another reason why the microflora suffers is nutrition. Our diet today is high in carbohydrates and low in protein. If you remember what the diet of our grandparents included, it turns out that they ate much more healthy food: for example, fresh vegetables, gray bread - simple and healthy food that has a beneficial effect on the microflora.

Also, the cause of violations of the intestinal microflora are diseases of the gastrointestinal tract, fermentopathy, active therapy with antibiotics, sulfa drugs, chemotherapy, hormonal therapy. Dysbacteriosis is favored by harmful environmental factors, starvation, depletion of the body due to serious illnesses, surgical interventions, burn disease, and a decrease in the body's immunological reactivity.

Prevention of microflora

In order to be in good shape, a person needs to maintain a balance of microflora that supports his immune system. Thus, we help the body resist stress and cope with pathogenic microbes on its own. That is why the microflora must be taken care of daily. This should become as common as brushing your teeth in the morning or taking vitamins.

Prevention of violations of microflora is aimed at maintaining beneficial bacteria in the body. This is facilitated by eating foods rich in plant fiber (vegetables, fruits, cereals, wholemeal bread), as well as fermented milk products.

Today, from TV screens, we are offered to start the day with a “sip of health”: kefirs and yogurtsenriched with bifidobacteria. However, it must be remembered that the amount of these beneficial elements in products with a long shelf life is quite small in order to stimulate the growth of microflora. Therefore, as a preventive measure, it is worth considering fermented milk products (kefirs, tans, etc.), which contain truly “live cultures”. As a rule, these products are sold in pharmacy chains and their shelf life is limited. And, of course, do not forget about the rules of healthy eating, sports and mental balance - all this helps to maintain immunity at its best!

Intestinal dysbacteriosis are conditions in which the normal microbial composition of the intestine.

Representatives of the so-called normal microflora live on the skin, in the urogenital tract, in the pancreas, etc., as well as on the mucous membranes of the upper respiratory tract and perform functions peculiar only to them, which we have already discussed in detail in previous chapters...

Including normal microflora is present in a small amount in the esophagus (this microflora practically repeats the microflora of the upper respiratory tract), in the stomach (the microbial composition of the stomach is poor and is represented by lactobacilli, streptococci, helicobacteria and yeast-like fungi resistant to stomach acid), in duodenum and small intestine the microflora is not numerous (represented mainly by streptococci, lactobacilli, veillonella), in the air intestine the number of microbes is higher (E. coli, etc. are added to all of the above microorganisms). But the largest number of microorganisms of normal microflora lives in the large intestine.

About 70% of all microorganisms of normal human microflora are concentrated precisely in the large intestine. If you put together the entire intestinal microflora - all its bacteria, then put it on a scale and weigh it, then you get about three kilograms! We can say that the human microflora is a separate human organ, which is of great importance for human life as well as the heart, lungs, liver, etc.

The composition of the intestinal microflora of a healthy person

99% of the microbes in the intestines are useful human helpers. These microorganisms are permanent inhabitants of the intestine, so they are called permanent microflora. These include:

• The main flora is bifidobacteria and bacteroids, the amount of which is 90-98%;
• Associated flora- lactobacilli, propionobacteria, E. coli, enterococci. Their number is 1-9% of all bacteria.

Under certain conditions, all representatives of the normal microflora, with the exception of bifido-, lactobacilli and propionobacteria, have the ability to cause diseases, i.e. bacteroids, Escherichia coli, enterococci, under certain circumstances, have pathogenic properties (I will talk about this a little later).

• Bifidobacteria, lactobacilli, propionobacteria are absolutely positive microorganisms and under no circumstances will they perform a pathogenic harmful function in relation to the human body.

But in the intestine there is also the so-called residual microflora: staphylococci, streptococci, clostridia, klebsiella, yeast-like fungi, citrobacter, veillonella, proteus and some other “malicious” pathogenic microorganisms ... As you understand, under certain conditions, these microorganisms perform a lot of pathogenic functions that are harmful to humans. But in a healthy state of a person, the number of these bacteria does not exceed 1%, respectively, while they are in the minority, they are simply not able to bring any harm, but, quite the contrary, they benefit the body, being a conditionally pathogenic microflora and performing immunogenic function(this function is one of the main functions of the microflora of the upper respiratory tract, I already mentioned it in chapter 17).

Microflora imbalance

All these bifidobacteria, lactobacilli and others perform a huge number of different functions. And if the normal composition of the intestinal microflora is shaken, the bacteria will not be able to cope with their functions, then ...

- Vitamins from food simply will not be absorbed and assimilated, hence a million diseases.

- A sufficient amount of immunoglobulins, interferons, lysozyme, cytokines and other immune factors will not be produced, which will result in a decrease in immunity and endless colds, infectious diseases, acute respiratory infections, acute respiratory viral infections, and influenza. A small amount of the same immunoglobulins, interferons, lysozyme, etc. will also be in mucous secretions, as a result of which the microflora of the respiratory tract will be disturbed and cause a variety of rhinitis, pharyngitis, tonsillitis, bronchitis, etc. The acid balance in the nasal cavity, pharynx, throat, and mouth will be disturbed - pathogenic bacteria will continue to increase their populations.

- If the renewal of cells of the intestinal mucosa is disturbed, many different poisons and allergens that must remain in the intestines will now begin to be absorbed into the blood, poisoning the entire body, hence all kinds of diseases arise, including many allergic diseases (bronchial asthma, allergic dermatitis, etc. .).

- Digestive disorders, absorption of decay products of putrefactive microflora can be reflected in peptic ulcer, colitis, gastritis, etc.

- If patients with diseases of the gastrointestinal tract, for example, pancreatitis, have intestinal dysfunction, then dysbacteriosis, which successfully develops against the background of this disease, is most likely to blame.

— Gynecological diseases (during the transition of microorganisms to the skin of the perineum, and then to the urinary organs), purulent-inflammatory diseases (boils, abscesses, etc.), metabolic disorders (menstrual irregularities, atherosclerosis, urolithiasis, gout), etc. .

- Disorders of the nervous system with all kinds of manifestations, etc.

- Skin diseases.

The diseases caused can be listed for a very, very long time!

The human body is a very fine system that is capable of self-regulation, this system is not easy to unbalance ... But some factors still affect the composition of the intestinal microflora. These may include the nature of nutrition, season, age, but these factors have little effect on fluctuations in the composition of microflora and are quite fixable, the balance of microflora is restored very quickly or a slight imbalance does not affect human health in any way. The question arises differently when, due to serious malnutrition or some other reasons, the biological balance of the intestinal microflora is disturbed and begins to pull along a whole chain of reactions and disturbances in the work of other organs and systems of the body, mainly diseases of the nasal cavity, throat, lungs, frequent colds, etc. That's it then and you need to talk about dysbacteriosis.

Microorganisms belonging to the normal intestinal microflora colonize both the lumen of the intestinal tract and the surface of the mucous membrane.

Gram-positive obligate anaerobic bacteria

Bifidobacteria are the most significant representatives of obligate bacteria in the intestines of children and adults. These are anaerobic bacteria, morphologically representing large gram-positive non-spore-forming rods of an even or slightly curved shape. The ends of the rods in most bifidobacteria are forked, but can also be thinned or thickened in the form of spherical swellings. Among the various types of bifidobacteria in breastfed children, Bifidobacterium bifidum predominates. Most of the bifidobacteria are located in the large intestine, being its main parietal and luminal microflora. Bifidobacteria are present in the intestines throughout a person's life, in children they make up from 90 to 98% of all intestinal microorganisms, depending on age. The dominant position in the intestinal microbial landscape in healthy breastfed newborns is occupied by bifidoflora by the 5–20th day of birth. Normally, the number of bifidobacteria in infants is 10 9 -10 10 CFU / g of feces, in older children and adults - 10 8 -10 9 CFU / g.

Bifidobacteria perform different functions:

By association with the intestinal mucosa, the physiological protection of the intestinal barrier from the penetration of microbes and toxins into the internal environment of the body is carried out;

They have high antagonistic activity against pathogenic and opportunistic microorganisms due to the production of organic fatty acids;

Participate in the utilization of food substrates and the activation of parietal digestion;

They synthesize amino acids and proteins, vitamin K, pantothenic acid, B vitamins: thiamine, riboflavin, nicotinic acid, folic acid, pyridoxine and cyanocobalamin;

Contribute to the strengthening of the processes of absorption through the walls of the intestine of calcium ions, iron, vitamin D;

They participate in cellular immunity reactions, prevent the degradation of secretory immunoglobulin A, stimulate interferon formation and produce lysozyme.

Bifidobacteria can be resistant to penicillin, streptomycin, rifampicin. Diseases caused by bifidobacteria are unknown.

Lactobacilli are obligate microflora, they are gram-positive, rod-shaped bacteria with pronounced polymorphism, arranged in chains or singly, non-spore-forming. The genus of lactobacilli includes 44 species.

Lactoflora inhabits the body of a newborn child in the early postnatal period. The habitat of lactobacilli is the various parts of the gastrointestinal tract, from the oral cavity to the large intestine, where they maintain a pH of 5.5-5.6. Being constantly present in the body, in a number of periods in the life of girls and women of reproductive age, they are the prevailing flora of the vulva and vagina. Lactoflora can be found in human and animal milk. In healthy breastfed children, lactobacilli are found in the amount of 10 6 -10 7 CFU / g of the test material. In artificially fed children, the level of lactobacilli is often higher, reaching 10 8 CFU/g of the test material. In 73% of adults, lactobacilli were detected in the amount of 10 9 CFU/g of the test material, and in persons using a strict vegetarian diet, lactobacilli were detected in 95% of cases in the amount of 10 11 CFU/g of the test material.

Lactobacilli in the process of life enter into a complex relationship with other microorganisms, as a result of which putrefactive and pyogenic opportunistic microorganisms, primarily proteas, as well as pathogens of acute intestinal infections, are suppressed. In the process of normal metabolism, they are able to form lactic acid, hydrogen peroxide, produce lysozyme, and other substances with antibiotic activity: reuterin, plantaricin, lactocidin, lactolin. Lactobacilli are assigned an immunomodulatory role, including stimulation of the phagocytic activity of neutrophils, macrophages, the synthesis of immunoglobulins and the formation of interferons, interleukin 1 and tumor necrosis factor alpha. In the stomach and small intestine, lactobacilli, in cooperation with the host organism, are the main microbiological link in the formation of colonization resistance. Lactobacilli are often resistant to penicillin and vancomycin.

Eubacteria are gram-positive, non-spore-forming, polymorphic rod-shaped bacteria or coccobacilli, strict anaerobes. These microorganisms are rarely found in children during breastfeeding. However, in artificially fed children, bacteria belonging to this genus can be detected in a large percentage of cases in amounts of 10 10 CFU / g of the test material, and more characteristic of healthy adults. of people. The role of these bacteria is still not clear enough, but it has been established that E. lentum are involved in the transformation of cholesterol into coprostanol. Other types of eubacteria are involved in the deconjugation of bile acids.

Peptostreptococci are non-fermenting gram-positive anaerobic streptococci. They belong to the obligate intestinal microflora. Just like eubacteria, they are rare in children during breastfeeding, but in children receiving artificial nutrition, their number can reach from 10 9 CFU / g of the test material. In the intestinal microflora of adult healthy people, their numerical level is from 10 9 to 10 10 CFU/g of the material under study. In the process of life, peptostreptococci form hydrogen, which in the intestine turns into hydrogen peroxide, which helps to maintain a pH of 5.5 and below, participate in the proteolysis of milk proteins, fermentation of carbohydrates. Does not have hemolytic properties. Getting as a result of translocation into habitats unusual for them, they can become the etiological factor of various infections. Often they are sown in septicemia, osteomyelitis, purulent arthritis, appendicitis and other deep abscesses, occupying, according to various estimates, the second place in the group of anaerobic bacteria in terms of frequency of detection in pathological material. Along with other anaerobes, they are detected in gingivitis and periodontitis.

Clostridia are gram-positive, spore-forming, often motile, rod-shaped bacteria, strict anaerobes. Mobility is carried out due to peritrichially located flagella. They belong to an optional part of the normal intestinal microflora. These bacteria are involved in the deconjugation of bile acids. In addition, many lecithinase-negative clostridia are involved in maintaining colonization resistance by suppressing the multiplication of pathogenic clostridia in the intestine. On the other hand, some clostridia can produce toxic metabolic products when proteins are broken down. With a decrease in the body's resistance, they can become they can become the cause of endogenous infection. In the intestines of newborns, these bacteria appear by the 6th–7th day of life and can reach a level of 106–107 CFU/g of the test material. Subsequently, in children who are breastfed, lecithinase-negative clostridia are detected only in 50% of children, and their level normally does not exceed 10 6 CFU/g of the test material. In artificially fed children, the number of these microorganisms often exceeds the norm and reaches 10 7 -10 8 CFU / g of the test material, while Clostridium difficile and Clostridium perfringens can often be found in them, capable of producing enterotoxins. In addition, C. difficile is an etiological factor in pseudomembranous colitis, which often occurs during antibiotic treatment. Antibiotics, by suppressing the normal intestinal microflora, especially the level of non-toxigenic clostridia, lead to the overgrowth of C. difficile. In adults, clostridia levels may be 10 6 -10 7 cfu/g of test material for lecithinase-negative clostridia and less than 10 4 -10 5 cfu/g of test material for lecithinase-positive clostridia. However, this balance changes in older people. After 65–70 years, an increase in the number of clostridia is often found against the background of a decrease in the level of bifidobacteria. In addition, an increase in the level of clostridia occurs with an unbalanced diet with a predominance of meat food in the diet.

Gram-negative obligate anaerobic bacteria

The bacteria included in this group and related to the endogenous flora of the human intestine, primarily include bacteroids, fusobacteria and veillonella. It should be noted that bacteria belonging to the genera Porphyromonas and Prevotella, which are often isolated from the human oral cavity, can also be isolated from the intestines of a healthy person.

Bacteroides are gram-negative, non-spore-forming, polymorphic rods, strict anaerobes. Along with bifidobacteria, they colonize the intestines of newborns by the 6–7th day of life. During breastfeeding, they are excreted in approximately 50% of children, and their level, inferior to the level of bifidobacteria, does not normally exceed 10 9 CFU / g of the test material. In artificially fed children, bacteroids are sown in a large percentage of cases in the amount of 10 10 CFU / g. In adults, the normal level of bacteroids reaches 10 9 -10 10 CFU/g of the test material. The role of bacteroids has not been fully elucidated, but it has been established that they take part in digestion, break down bile acids, and participate in lipid metabolism.

Fusobacteria are gram-negative, non-spore-forming, polymorphic rod-shaped bacteria. Strict anaerobes. They are characteristic of the intestinal microflora of adults, in which these microorganisms are found at a concentration of 10 8 -10 10 CFU/g of the test material. Fusobacteria are often isolated from pathological material with purulent complications of various localization. At the same time, the species F.necrophorum is the most common. Bacteria of this species are able to secrete leukotoxin and platelet aggregation factor responsible for thromboembolism in severe septicemia.

Veillonella are gram-negative obligate anaerobic cocci. Their level in children of the first year of life does not exceed 10 5 CFU / g of the test material, and they are excreted by less than 50% of children. On the other hand, in children receiving artificial nutrition, they are found much more often in concentrations often exceeding 10 8 CFU / g of the material under study. Veileonella are bacteria that weakly ferment sugars and are capable of reducing nitrate, and have complex nutritional needs. Their distinguishing feature is the ability to produce gas, often in large quantities, which, if they multiply excessively in the intestines, can cause dyspeptic disorders.

Facultative anaerobic microorganisms

Escherichia are Gram-negative motile rods belonging to the family Enterobacteriaceae. The amount is insignificant compared to the dominant, non-spore-forming anaerobes (bifidobacteria, lactobacilli, bacteroids). The quantitative level of Escherichia in a healthy person is less than 0.01% of the total number of the most important representatives of the normal microflora. In the human intestine, Escherichia appear in the first days after birth, remaining during a person's life at a level of 107–108 CFU/g of the material under study.

The main functions of Escherichia in the body:

Promote the hydrolysis of lactose;

Participate in the production of vitamins, primarily vitamin K, group B;

Produces colicins - antibiotic-like substances that inhibit the growth of enteropathogenic Escherichia coli;

Stimulates antibody formation and has a powerful immunomodulatory effect;

Promotes the activation of systemic humoral and local immunity;

Causing constant antigenic irritation of the local immunity system, Escherichia maintain it in a physiologically active state: they initiate the synthesis of secretory immunoglobulins in the intestine, which are capable of interacting with pathogenic microorganisms belonging to the Enterobacteriaceae family due to cross-reactions, and prevents their penetration into the mucous membrane of the intestinal wall.

Along with useful properties, many Escherichia strains have a number of pathogenic properties. The percentage of enterropathogenic Escherichia strains in the feces of healthy people ranges from 9.1% to 32.4%. Pathogenic variants can cause colienteritis, cholera-like and dysenteric diseases. It is not uncommon for E. coli in association with staphylococci or other opportunistic microorganisms to cause nosocomial infections in surgical, gynecological clinics and in neonatal wards. At the same time, hospital strains often have multiple resistance to antibiotics. Formula-fed children are more susceptible to colienteritis, which may be due to endogenous Escherichia.

An important diagnostic criterion for assessing the severity of intestinal dysbiosis is the determination of the number of hemolysin-producing and lactose-negative Escherichia coli. Normally, Escherichia with such properties are detected only in 2% of the examined in an amount not exceeding 10 4 CFU / g. In intestinal dysbacteriosis, they can be excreted with a frequency above 40-50%, and their level often significantly exceeds the level of normal lactose-positive non-hemolysin-producing E. coli. On the other hand, a sharp decrease in the number of normal Escherichia, which occurs in some cases with dysentery, should be regarded as a state of microflora that requires correction.

Other representatives of the Enterobacneriaceae family: Klebsiella, Proteus, Morganella, Enterobacter, Citrobacter, Serratia, etc. are conditionally pathogenic microorganisms. They can be part of the facultative intestinal microflora in an amount not exceeding 10 4 CFU / g. The decrease in the resistance of the human body, due to various factors, such as antibiotic therapy, hormonal therapy, the use of cytostatics, contributes to the implementation of the pathogenic properties of these microorganisms, which, in turn, leads to the development of diarrhea and other syndromes associated with a violation of the microflora.

Propionic bacteria are Gram-positive bacteria. These are "domesticated" microorganisms that have long been used in cheese making.

The probiotic properties of propionic acid bacteria are associated with:

Formations of useful metabolites and antimicrobial components;

Antimutagenic properties;

They are a source of beta-galactosidase, an enzyme that breaks down lactose;

Promote the growth of bifidobacteria;

Form in significant quantities low-calorie sugar - trehalose;

Their biomass contains trace elements in the amount (mg/kg) of Mn(267), Cu (102), Fe(535), which exceeds their content in the biomass of dairy and bifidobacteria.

They reduce the activity of the enzymes beta-glucuronidase, nitroreductase, nitrogen reductase, under the influence of which fecal procarcinogens are converted into active forms of carcinogens.

In addition, they form and accumulate NO during the reduction of nitrates and nitrites. Nitric oxide is important for many vital functions such as neurotransmission, vasodilation, intestinal peristalsis, and mucosal protection. Chronic intestinal disorders may be associated with insufficient formation of nitric oxide in the body.

The antimutagenic activity of propionic acid bacteria against mutations induced by 4-nitroquinoline and nitrosoguanidine (point mutations), as well as by 9-aminoacridine and alpha-nitrofluorene (frameshift mutations) was demonstrated. Considering the fact that many of the foods we eat contain some amount of mutagens (especially when frying food, eating moldy foods), the antimutagenic properties of propionic acid bacteria can hardly be overestimated. Propionic acid bacteria form and secrete bifidogenic metabolites that promote the growth of a number of strains of bifidobacteria. Moreover, this influence is reciprocal.

Effective probiotic bacteria must have good adhesion and the ability to survive despite many adverse factors, including stomach acids and enzymes, bile salts and enzymes of the small intestine, as well as the antagonistic action of other bacteria. In model experiments, it was shown that the level of adhesion of propionic bacteria is 0.2–0.6% of all introduced bacteria. In lactobacilli and bifidobacteria, the level of adhesion is much higher: from 1.3 to 24.3%. It has been established that the adhesion of propionic bacteria can be increased by their preliminary coaggregation with other probiotic bacteria. The resistance of propionic bacteria to acid and bile salts was increased by preliminary adaptation to these stress factors.

Staphylococci- Gram-positive cocci, they colonize the intestines from the first days of a newborn's life and subsequently are present in almost all parts of the gastrointestinal tract. In the first year of life, their level, both in children who are breastfed and in children who are bottle-fed, normally ranges from 10 4 to 10 5 CFU / g. Moreover, these indicators refer exclusively to non-pathogenic species of staphylococci and, above all, to Staphylococcus epidermidis, which is most often found in the human intestine. Subsequently, their number decreases, and in older children, as in adults, their level normally does not exceed 10 3 -10 4 CFU / g. In the intestines of a healthy person, staphylococci belonging to the species S. aureus can also be found, but their number should normally not exceed 10 2 CFU / g of the test material. Being present in the intestine in small concentrations, staphylococci, which have pathogenic properties, do not cause the formation of pathological processes until the resistance of the macroorganism decreases as a result of any adverse effects. The development of staphylococcal infections is also possible in the case of transmission of these bacteria from "healthy" carriers to people with reduced resistance: from the staff of medical institutions to patients, from mother to child, for example, during breastfeeding. In many cases, pathogenic staphylococci belonging to nosocomial strains are resistant to antibiotics, which often explains the lack of a positive effect from antibiotic therapy. S. aureus can cause inflammatory diseases of the digestive tract, food poisoning, and septic processes.

streptococci- Gram-positive cocci. The main representatives of this genus are enterococci: Enterococcus faecalis and E. Faecium. In newborns, they are sown from the first days of life, and subsequently in the first year, in children who are breastfed, their level, while remaining stable, ranges from 10 6 to 10 7 CFU / g. On the other hand, in the case when a child receives artificial feeding, the number of these microorganisms may exceed the norm and reach up to 10 8 -10 9 CFU / g of the test material. In the intestines of adult healthy people, their number is 10 7 -10 8 CFU / g. Moreover, E. faecium has a less pathogenic effect than E. Faecalis. By colonizing the intestinal surface and producing lactic acid during the fermentation of carbohydrates, intestinal streptococci acidify the environment and thus participate in maintaining colonization resistance at an optimal level. However, their excessive reproduction, associated with a decrease in the levels of obligate representatives of the intestinal microflora in dysbiosis of various etiologies, can lead to the development of endogenous infectious processes.

bacilli Gram-positive, rod-shaped, spore-forming bacteria. Thanks to their spores, which provide them with high resistance to the external environment, these organisms are distributed almost everywhere. Their main ecological niche is the soil. Often, bacilli are found in water and food, through which they enter the human digestive tract. The main species found in the human intestine is Bacillus subtilis, sometimes Bacillus cereus can be isolated. However, when entering the intestines in high concentrations, bacilli can cause food poisoning. They are rarely sown in healthy children who are breastfed, in amounts not exceeding 10 2 -10 3 CFU / g of the test material. In artificially fed children, bacilli can be detected in 50% of cases in an amount reaching 10 8 -10 9 CFU / g of the test material. In healthy adults, the level of bacilli in the norm should not exceed 10 4 CFU / g of the test material.

Yeast-like fungi of the genus Candida are rarely found in healthy people and adults. Their normal level cannot exceed 10 4 CFU/g of feces. However, in each case, the detection of yeast-like fungi, even in small quantities, especially in young children and in patients with reduced immune resistance, should be accompanied by a clinical examination in order to exclude candidiasis. The main species that are most often found in the examination of the intestinal microflora are C. albicans and C. tropicalis.

As can be seen from the above material, none of the body's functions can be realized without the participation of microflora. By creating an acidic environment, due to the formation of organic acids and a decrease in the pH of the colon to 5.3-5.8, the symbiotic microflora prevents the reproduction of pathogenic, putrefactive and gas-producing intestinal microflora. Bifido- and lactobacilli, having a pronounced antagonistic activity against pathogenic bacteria, regulate the quantitative and qualitative composition of the intestinal microflora, slow down the growth and reproduction of pathogenic and opportunistic microbes in it.

The antagonistic activity of the intestinal microflora is provided by a number of factors.

Intestinal saprophytes versus pathogenic bacteria:

They produce a variety of bactericidal and bacteriostatic substances, including antibiotic-like ones;

Contribute to the enzymatic digestion of food ingredients, breaking down proteins, fats, high molecular weight carbohydrates;

Proteins and carbohydrates not absorbed in the small intestine in the caecum undergo deeper bacterial cleavage, mainly by Escherichia coli and anaerobes;

Perform a detoxification function: inactivate enterokinase, alkaline phosphatase;

Promote the breakdown of cellulose;

They play an important role in the final stages of cholesterol and bile acid metabolism. The conversion of cholesterol into non-absorbable coprostapol in the colon occurs with the participation of saprophytes;

Participate in the metabolism of cholesterol, contributing to its conversion into bile acids, and the transformation of bilirubin into stercobilin and urobilin;

Stimulate intestinal peristalsis, optimize the evacuation of intestinal contents;

Intestinal microflora is a collection of non-pathogenic microorganisms that live in the intestines of a healthy person. Human organisms and bacteria coexist in conditions of mutually beneficial cooperation - symbiosis. Flora in the intestine appears in infancy and persists throughout a person's life.

Members of the intestinal flora

Microorganisms in the human intestine

Violation of the intestinal microflora

Changing the composition of the intestinal microflora can lead to serious consequences.

It can be associated both with the penetration of pathogenic microorganisms that are not normally found in the digestive system, or with a decrease in the content of normal microflora -.

The reasons

Symptoms

Symptoms of dysbiosis depend on the severity of disorders and the presence of concomitant diseases.

• . The patient develops flatulence, belching, diarrhea or constipation may occur. Patients constantly feel an unpleasant aftertaste in the mouth.
• . Many patients note the appearance of food allergies to those products that were previously tolerated normally. This manifestation is most typical for children. Allergies can be expressed as skin symptoms (itching, hives, swelling) and intestinal symptoms. These include sharp pains in the lower abdomen, nausea, vomiting, loose stools with foam.
• Malabsorption. With prolonged presence of dysbacteriosis, this leads to a change in the entire metabolism - the occurrence of energy deficiency, hypovitaminosis. The condition is usually accompanied by anemia, calcium deficiency, and other ionic disorders.
• Intoxication. It is characterized by the occurrence of weakness, headache, a slight increase in temperature.

How to check the intestinal microflora?

To assess the state of the intestinal microflora, the patient is carried out. For this, either a scraping or an aspirate from the intestine is taken. The resulting material is sent for bacteriological examination. In the laboratory, bacteria are cultured on nutrient media. According to the grown colonies of microorganisms, one can judge the state of the intestinal flora. This study is an accurate way to diagnose its disorders.

Indirectly, the presence of dysbacteriosis may be indicated by research methods that are aimed at detecting changes in the composition of feces. These include the biochemical study of feces. Such diagnostics makes it possible to detect characteristic chemical changes that indicate the presence of certain microorganisms in the intestine.

Prevention and treatment of microflora disorders

Food

First of all, it involves the preparation of a balanced diet. It must necessarily include fermented milk products containing. Food should contain enough natural vitamins. At the risk of seasonal hypovitaminosis, it is recommended to additionally use multivitamin complexes.

Destruction of pathogenic bacteria

To eliminate pathogens from the intestines, special antibacterial drugs with selective effects are used. They do not affect the state of normal microflora, but at the same time destroy harmful bacteria. This group includes non-absorbable antibiotics (eg, nifuroxazide) and (rifaximin).

Restoration of normal microflora

Medicines from several groups are used for:

• include live cultures of microorganisms that are normally found in the human intestine.
• Medicines from the group include all the necessary substances so that “beneficial” bacteria can multiply rapidly.
• Both those and other components are part of the combined means -.

Restoration of immunity

Normalization of local immunity helps to maintain a constant composition of the intestinal flora. For this purpose, the patient is prescribed drugs with an immunomodulatory effect - drugs based on echinacea, nucleic acids.