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 unique to them, which we have already discussed in detail in previous chapters...

Including normal microflora is present in small quantities 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, Helicobacter and yeast-like fungi resistant to stomach acid), in the duodenum and in the small intestine the microflora is small (represented mainly by streptococci, lactobacilli, veillonella), in the ileum 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 in the large intestine. If you put together all the intestinal microflora - all its bacteria, then put it on a scale and weigh it, you will get about three kilograms! We can say that the human microflora is a separate human organ, which is of utmost importance for human life, just like the heart, lungs, liver, etc.

Composition of the intestinal microflora of a healthy person

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

• The main flora is bifidobacteria and bacteroides, the number 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 normal microflora, with the exception of bifidobacteria, lactobacilli and propionobacteria, have the ability to cause diseases, i.e. Bacteroides, Escherichia coli, and enterococci have pathogenic properties under certain circumstances (I’ll talk about this a little later).

1. Bifidobacteria, lactobacilli, propionobacteria are absolutely positive microorganisms and under no circumstances will 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 “harmful” pathogenic microorganisms... As you understand, under certain conditions these microorganisms perform a lot of pathogenic harm to human functions. But in a healthy person, the number of these bacteria does not exceed 1%, respectively, while they are in the minority, they are simply not capable of causing any harm, but, quite the contrary, they benefit the body, being opportunistic microflora and performing an immunogenic function (this function 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 absorbed, 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 disrupted and cause a variety of rhinitis, pharyngitis, tonsillitis, bronchitis, etc. The acid balance in the nasal cavity, pharynx, throat, mouth will be disrupted - pathogenic bacteria will continue to increase their populations.

If the renewal of cells in the intestinal mucosa is disrupted, 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 sorts 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 ulcers, colitis, gastritis, etc.

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

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

Nervous system disorders with all sorts of manifestations, etc.

Diseases caused by intestinal dysbiosis can be listed for a very, very long time!

The human body is a very finely tuned system that is capable of self-regulation; this system is not easy to throw out of balance... But some factors still influence the composition of the intestinal microflora. These may include the nature of nutrition, time of year, age, however, these factors have little effect on fluctuations in the composition of the microflora and are quite correctable, the balance of the microflora is restored very quickly or a small imbalance does not affect human health in any way. The question arises differently when, due to serious nutritional disorders or some other reasons, the biological balance of the intestinal microflora is disturbed and begins to lead to a whole chain of reactions and disturbances in the functioning of other organs and systems of the body, mainly diseases of the nasal cavity, throat, lungs, frequent colds, etc. That’s when we need to talk about dysbiosis.

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Barrier function – neutralization of various toxins and allergens;

Enzymatic function - production of a significant amount of digestive enzymes and, above all, lactase;

Ensuring normal motility of the gastrointestinal tract;

Participation in metabolism;

Participation in the body’s immune reactions, stimulation of defense mechanisms and competition with pathogenic and opportunistic microorganisms.

Obligate - the main or indigenous microflora (it includes bifidobacteria and bacteroides), which make up 90% of the total number of microorganisms;

Facultative - saprophytic and opportunistic microflora (lactobacteria, Escherichia, enterococci), which makes up 10% of the total number of microorganisms;

Residual (including transient) - random microorganisms (Citrobacter, Enterobacter, Proteus, yeast, clostridia, staphylococci, aerobic bacilli, etc.), which constitutes less than 1% of the total number of microorganisms.

Mucosal (M) flora - mucosal microflora interacts with the mucous membrane of the gastrointestinal tract, forming a microbial-tissue complex - microcolonies of bacteria and their metabolites, epithelial cells, goblet cell mucin, fibroblasts, immune cells of Peyre's patches, phagocytes, leukocytes, lymphocytes, neuroendocrine cells;

Luminal (L) flora - luminal microflora is located in the lumen of the gastrointestinal tract and does not interact with the mucous membrane. The substrate for its life activity is indigestible dietary fiber, on which it is fixed.

Endogenous factors - the influence of the mucous membrane of the digestive canal, its secretions, motility and the microorganisms themselves;

Exogenous factors - influence directly and indirectly through endogenous factors, for example, the intake of one or another food changes the secretory and motor activity of the digestive tract, which transforms its microflora.

Bacteroides (especially Bacteroides fragilis),

Anaerobic lactic acid bacteria (for example, Bifidumbacterium),

Clostridia (Clostridium perfringens),

Gram-negative coliform bacteria (primarily Escherichia coli - E.Coli),

Fungi of the genus Candida,

Certain types of spirochetes, mycobacteria, mycoplasmas, protozoa and viruses.

Intestinal dysbiosis. Causes, symptoms, modern diagnosis and effective treatment

FAQ

The site provides reference information. Adequate diagnosis and treatment of the disease is possible under the supervision of a conscientious doctor.

Anatomy and physiology of the intestine

1. The small intestine, which is the initial section of the intestine, consists of loops that are longer than the large intestine (from 2.2 to 4.4 m) and smaller in diameter (from 5 to 3 cm). The processes of digestion of proteins, fats and carbohydrates take place in it. The small intestine begins at the pylorus of the stomach and ends at the ileocecal angle. The small intestine is divided into 3 sections:

• The initial section is the duodenum, starts from the pylorus of the stomach, has the shape of a horseshoe, goes around the pancreas;
• The jejunum is a continuation of the duodenum, it makes up approximately the initial 6-7 loops of the small intestine, the border between them is not pronounced;
• The ileum is a continuation of the jejunum and is represented by the following 7-8 loops. It ends at a right angle into the initial part of the large intestine (cecum).

1. The large intestine is the final section of the digestive tract, where water is absorbed and formed feces are formed. It is located so that it borders (surrounds) the loops of the small intestine. Its wall forms protrusions (haustra), which is one of the differences from the wall of the small intestine. The length of the large intestine is about 150 cm and the diameter is from 8 to 4 cm, depending on the section. The large intestine consists of the following sections:

• The cecum with the appendicular process is the initial section of the large intestine, located below the ileocecal angle, its length is from 3 to 8 cm;
• The ascending part of the colon is a continuation of the cecum, occupies the extreme right lateral position of the abdominal cavity, rises upward from the level of the ilium to the level of the lower edge of the right lobe of the liver, and ends with the right flexure of the colon;
• The transverse colon starts from the right flexure of the colon (level of the right hypochondrium), passes in the transverse direction and ends with the left flexure of the colon (level of the left hypochondrium);
• The descending part of the colon occupies the extreme left lateral position of the abdominal cavity. Starts from the left flexure of the colon, goes down to the level of the left ilium;
• The sigmoid colon, 55 cm long, is a continuation of the previous section of the intestine, and at the level of the 3rd sacral vertebra it passes into the next section (rectum). The diameter of the sigmoid colon, compared with the diameter of the rest of the large intestine, is the smallest, about 4 cm;
• The rectum, is the final section of the large intestine, has a length of about 18 cm. It starts from the level of the 3rd sacral vertebra (end of the sigmoid colon) and ends with the anus.

What is normal intestinal flora?

Normally, the intestinal flora is represented by 2 groups of bacteria:

Symptoms characteristic of 3rd and 4th degree intestinal dysbiosis:

1. Abnormal stool:

• Most often it manifests itself in the form of loose stools (diarrhea), which develops as a result of increased formation of bile acids and increased intestinal motility, inhibiting the absorption of water. Later, the stool becomes unpleasant, putrid odor, mixed with blood or mucus;
• With age-related (in older people) dysbiosis, constipation most often develops, which is caused by a decrease in intestinal motility (due to a lack of normal flora).

1. Bloating is caused by increased formation of gases in the large intestine. The accumulation of gases develops as a result of impaired absorption and excretion of gases by the altered intestinal wall. A swollen intestine may be accompanied by rumbling and cause unpleasant sensations in the abdominal cavity in the form of pain.
2. Cramping pain is associated with an increase in pressure in the intestines; after the passage of gas or stool, it decreases. With dysbiosis of the small intestine, pain occurs around the navel; if the large intestine suffers, the pain is localized in the iliac region (lower abdomen on the right);
3. Dyspeptic disorders: nausea, vomiting, belching, loss of appetite, are the result of impaired digestion;
4. Allergic reactions, in the form of itchy skin and rashes, develop after consuming foods that usually do not cause allergies, and are the result of insufficient antiallergic action and disrupted intestinal flora.
5. Symptoms of intoxication: there may be a slight increase in temperature up to 38 0 C, headaches, general fatigue, sleep disturbances, which are the result of the accumulation of metabolic products (metabolism) in the body;
6. Symptoms characterizing a lack of vitamins: dry skin, seizures around the mouth, pale skin, stomatitis, changes in hair and nails, and others.

Complications and consequences of intestinal dysbiosis

• Chronic enterocolitis is a chronic inflammation of the small and large intestines, developing as a result of prolonged action of pathogenic intestinal flora.

• Deficiency of vitamins and microelements in the body leads to the development of iron deficiency anemia, hypovitaminosis of B vitamins and others. This group of complications develops as a result of impaired digestion and absorption in the intestines.
• Sepsis (blood infection) develops as a result of pathogenic flora from the intestines entering the patient’s blood. Most often, this complication develops when the patient does not seek medical help in a timely manner.
• Peritonitis develops as a result of the aggressive action of pathogenic flora on the intestinal wall, with the destruction of all its layers and the release of intestinal contents into the abdominal cavity.
• The addition of other diseases as a result of decreased immunity.
• Gastroduodenitis and pancreatitis develop as a result of the spread of pathogenic intestinal flora through the digestive tract.
• The patient's weight loss develops as a result of impaired digestion.

Diagnosis of intestinal dysbiosis

1. Using an objective examination, which includes palpation of the abdomen, pain is determined along the small and/or large intestine.
2. Microbiological examination of stool: carried out to confirm the diagnosis of intestinal dysbiosis.

Indications for microbiological examination of stool:

• Intestinal disorders last a long time, in cases where it is not possible to isolate a pathogenic microorganism;
• Long recovery period after acute intestinal infections;
• The presence of purulent-inflammatory foci that are not amenable to antibiotic therapy;
• Impaired bowel function in individuals undergoing radiotherapy or exposure to radiation;
• Immunodeficiency conditions (AIDS, cancer and others);
• Retarded physical development of an infant and others.

Rules for collecting stool for microbiological examination: before collecting stool, 3 days before, you must be on a special diet that excludes products that increase fermentation in the intestines (alcohol, lactic acid products), as well as any antibacterial drugs. The feces are collected in a special sterile container equipped with a lid and a screwed-in spoon. To correctly evaluate the results, it is recommended to conduct the study 2-3 times, with an interval of 1-2 days.

There are 4 degrees of intestinal dysbacteriosis:

• 1st degree: characterized by a quantitative change in ischerichia in the intestine, bifidoflora and lactoflora are not changed, most often not clinically manifested;
• 2nd degree: quantitative and qualitative changes in ischerichia, i.e. a decrease in the amount of bifid flora and an increase in opportunistic bacteria (fungi and others), accompanied by local inflammation of intestinal areas;
• 3rd degree: change (decrease) in bifido and lactoflora and development of opportunistic flora, accompanied by intestinal dysfunction;
• 4th degree: the absence of bifid flora, a sharp decrease in lacto flora and the growth of opportunistic flora, can lead to destructive changes in the intestine, with the subsequent development of sepsis.

Treatment of intestinal dysbiosis

Drug treatment

Groups of drugs used for intestinal dysbiosis:

1. Prebiotics - have a bifidogenic property, i.e. contribute to the stimulation and growth and reproduction of microbes that are part of the normal intestinal flora. Representatives of this group include: Hilak-forte, Duphalac. Hilak-forte is prescribed dropwise 3 times a day.
2. Probiotics (eubiotics) are preparations containing live microorganisms (i.e. bacteria of normal intestinal flora), they are used to treat grade 2-4 dysbacteriosis.

• 1st generation drugs: Bifidumbacterin, Lifepack probiotics. They are liquid concentrates of lactobacilli and bifidobacteria and are not stored for long (about 3 months). This group of drugs is unstable under the influence of gastric juice or enzymes of the gastrointestinal tract, which leads to their rapid destruction and the intake of insufficient concentrations, the main disadvantage of 1st generation probiotics. Bifidumbacterin is prescribed orally, 5 doses of the drug 2-3 times a day, 20 minutes before meals;
• 2nd generation drugs: Bactisubtil, Flonivin, Enterol. They contain spores of bacteria of normal intestinal flora, which in the patient’s intestines secrete enzymes for the digestion of proteins, fats and carbohydrates, stimulate the growth of bacteria of normal intestinal flora, and also suppress the growth of putrefactive flora. Subtil is prescribed 1 capsule 3 times a day, 1 hour before meals;
• 3rd generation drugs: Bifikol, Linex. They consist of several types of bacteria from the normal intestinal flora, therefore they are highly effective compared to the previous 2 generations of probiotics. Linex is prescribed 2 capsules 3 times a day;
• 4th generation drugs: Bifidumbacterin forte, Biosorb-Bifidum. This group of drugs consists of bacteria of normal intestinal flora in combination with an enterosorbent (with activated carbon or others). Enterosorbent is necessary to protect microorganisms when passing through the stomach, it actively protects them from inactivation by gastric juice or enzymes of the gastrointestinal tract. Bifidumbacterin forte is prescribed 5 doses 2-3 times a day, before meals.

1. Symbiotics (Bifidobak, Maltodophilus) are combined preparations (prebiotic + probiotic), i.e. simultaneously stimulate the growth of normal flora and replace the missing number of microbes in the intestines. Bifidobac is prescribed 1 capsule 3 times a day, with meals.
2. Antibacterial drugs are used for the 4th degree of intestinal dysbiosis, to destroy pathogenic flora. The most commonly used antibiotics are: tetracyclines (Doxycycline), cephalosporins (Cefuroxime, Ceftriaxone), penicillins (Ampiox), nitroimidazoles: Metronidazole, prescribed 500 mg 3 times a day, after meals.
3. Antifungal drugs (Levorin) are prescribed if there are yeast-like fungi such as Candida in the stool. Levorin is prescribed 500 thousand units 2-4 times a day.
4. Enzymes are prescribed in case of severe digestive disorders. Mezim tablets, 1 tablet 3 times a day, before meals.
5. Sorbents are prescribed for severe signs of intoxication. Activated carbon is prescribed 5-7 tablets at a time, for 5 days.
6. Multivitamins: Duovit, 1 tablet 1 time per day.

Diet for intestinal dysbiosis

Prevention of intestinal dysbiosis

In second place for the prevention of intestinal dysbiosis is a balanced diet and a rational regimen.

Is there any intestinal dysbiosis at all? Does such a disease exist?

Western doctors never give this diagnosis to their patients. In Russian healthcare, dysbacteriosis is mentioned in a document called “Standards (protocols) for the diagnosis and treatment of diseases of the digestive system,” approved by order of the Ministry of Health of the Russian Federation No. 125 dated April 17, 1998. But even here it does not appear as an independent disease, but only in connection with other intestinal diseases.

Surely, when you took a blood test, you heard terms such as “increased leukocytosis”, “increased ESR”, “anemia”. Dysbacteriosis is something similar. This is a microbiological concept, one of the manifestations of the disease, but not the disease itself.

How is intestinal dysbiosis designated in the ICD?

Most often, such doctors use two codes:

• A04 - other bacterial intestinal infections.
• K63 - other specified diseases of the digestive system.

The word “dysbacteriosis” does not appear in either of the two paragraphs. This means that such a diagnosis indicates that the disease has not been fully diagnosed.

What diseases can be hidden under the term “dysbacteriosis”? Most often these are intestinal infections and helminthic infestations, celiac disease, irritable bowel syndrome, side effects of treatment with antibiotics, chemotherapy and some other drugs, all kinds of diseases that weaken the immune system. In young children, bowel symptoms may accompany atopic dermatitis.

Sometimes dysbiosis is a temporary condition, for example, in travelers, especially if they have poor personal hygiene. “Foreign” microflora enters the intestines, which a person does not encounter at home.

Which doctor treats intestinal dysbiosis?

Most often, diseases that lead to disruption of the intestinal microflora should be treated by an infectious disease specialist or gastroenterologist. A number of diseases are treated by a general practitioner in adults and by a pediatrician in children.

What is the best treatment for intestinal dysbiosis?

Although, relevant recommendations do exist - they are spelled out in the OST 91500.11 standard. It was put into effect by Order of the Ministry of Health of the Russian Federation dated 06/09/2003 N 231. This document suggests treating dysbiosis with the help of prebiotics and eubiotics, antibacterial and antifungal drugs.

But the effectiveness of these drugs against dysbiosis has not been proven. In the same OST there is the following phrase: “the degree of persuasiveness of evidence is C.” This means that there is not enough evidence. There is no evidence on which to recommend treatment of dysbiosis with these drugs.

Here it is once again appropriate to remember that doctors who work in clinics outside the CIS never give such a diagnosis to their patients, much less prescribe treatment against dysbiosis.

Is there a connection between intestinal dysbiosis and thrush?

The infection can develop in any organ. In this regard, candidiasis of the skin and nails, oral mucosa (this form is called thrush), intestines, and genitals is isolated. The most severe form of the disease is generalized candidiasis, or candidal sepsis, when the fungus affects the skin, mucous membranes, and internal organs.

Candida are opportunistic fungi. They are not always capable of causing infection, but only under certain conditions. One of these conditions is decreased immunity. Thrush may well be combined with intestinal damage, which leads to dysbiosis. There is, in fact, a connection between these two conditions.

In this case, the same reasons lead to the development of thrush and intestinal dysbiosis - decreased immunity and fungal infection. They need to be treated.

Is it possible to use folk remedies to treat intestinal dysbiosis?

Due to the fact that the topic is inflated and very popular, “remedies against dysbacteriosis” are offered by all kinds of traditional healers, healers, manufacturers of dietary supplements, and MLM companies. Food producers were not left out either.

As already mentioned above, dysbiosis as a disease does not exist, it does not have its own specific symptoms, and it cannot be cured without eliminating the root cause. Therefore, first of all, you need to visit a doctor, undergo an examination, establish the correct diagnosis and begin treatment.

What can a dysbacteriosis test show?

• The concept of “normal microflora” is very vague. Nobody knows the exact standards. Therefore, if you force any healthy person to take a test, many will be “identified” as having dysbacteriosis.
• The content of bacteria in feces differs from their content in the intestines.
• While the stool is delivered to the laboratory, the composition of the bacteria present in it may change. Especially if it is collected incorrectly, in a non-sterile container.
• The composition of the microflora in the human intestine can change depending on different conditions. Even if you take an analysis at different times from the same healthy person, the results can vary greatly.

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Intestinal microflora

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

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

But microflora disturbance can occur not only due to poor nutrition, but also due to the use of various antibiotics. In any case, microflora is disrupted.

Normal intestinal microflora

The main representatives of the obligatory microflora of the human colon are bifidobacteria, bacteriodes, lactobacilli, Escherichia 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. In a normal state of the intestine, there should be no pathogenic microflora; normal intestinal microflora in a person 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 years.

What function does normal intestinal microflora perform? First of all, protective. Thus, 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 have an antagonistic effect on pathogenic flora through immune mechanisms. In addition, on the surface of intestinal epithelial cells, representatives of normal microflora form the so-called “microbial turf”, which mechanically protects the intestine from the penetration of pathogenic microbes.

In addition to their protective function, normal colon microorganisms participate in the metabolism of the macroorganism. They synthesize amino acids, proteins, many vitamins, and 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 microflora disturbances

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

Another reason why microflora suffers is nutrition. Today our diet contains many carbohydrates and little protein. If we 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 disturbances in the intestinal microflora are diseases of the gastrointestinal tract, fermentopathy, active therapy with antibiotics, sulfonamide drugs, chemotherapy, and hormonal therapy. Dysbacteriosis is favored by harmful environmental factors, fasting, exhaustion 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. In this way, we help the body resist stress and cope with pathogenic microbes on its own. That is why microflora must be taken care of daily. This should become as common as brushing your teeth in the morning or taking vitamins.

Prevention of microflora disorders 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”: kefir and yoghurt enriched with bifidobacteria. However, we must remember that the amount of these useful 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, don’t forget about the rules of a healthy diet, exercise and mental balance - all this helps keep your immune system at its best!

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Normal intestinal microflora

Human evolution took place with constant and direct contact with the world of microbes, as a result of which close relationships were formed between macro- and microorganisms, characterized by a certain physiological need.

The settlement (colonization) of body cavities communicating with the external environment, as well as the skin, is one of the types of interaction of living beings in nature. Microflora is found in the gastrointestinal tract and genitourinary system, on the skin, mucous membranes of the eyes and respiratory tract.

The most important role is played by the intestinal microflora, since it occupies an area of ​​about 2 (for comparison, the lungs are 80 m2, and the skin of the body is 2 m2). It is recognized that the ecological system of the gastrointestinal tract is one of the body’s defense systems, and if it is violated in a qualitative and quantitative sense, it becomes a source (reservoir) of pathogens of infectious diseases, including those with an epidemic nature of spread.

All microorganisms with which the human body interacts can be divided into 4 groups.

■ The first group includes microorganisms that are not capable of long-term residence in the body, and therefore they are called transient.

Their detection during examination is random.

■ The second group is bacteria that are part of the obligate (most permanent) intestinal microflora and play an important role in activating the metabolic processes of the macroorganism and protecting it from infection. These include bifidobacteria, bacteroides, lactobacilli, E. coli, enterococci, and catenobacteria. Changes in the stability of this composition usually lead to health problems.

■ The third group is microorganisms, which are also found with sufficient constancy in healthy people and are in a certain state of equilibrium with the host organism. However, with a decrease in resistance, with changes in the composition of normal biocenoses, these opportunistic forms can aggravate the course of other diseases or themselves act as an etiological factor.

Their specific gravity in the microbiocenosis and their relationship with microbes of the second group are of great importance.

These include staphylococcus, yeast fungi, Proteus, streptococci, Klebsiella, Citrobacter, Pseudomonas and other microorganisms. Their specific gravity can be only less than 0.01-0.001% of the total number of microorganisms.

■ The fourth group consists of pathogens of infectious diseases.

The microflora of the gastrointestinal tract is represented by more than 400 species of microorganisms, with more than 98% of it being obligate anaerobic bacteria. The distribution of microbes in the gastrointestinal tract is uneven: each department has its own, relatively constant microflora. The species composition of the oral microflora is represented by aerobic and anaerobic microorganisms.

In healthy people, as a rule, the same types of Lactobadillus are found, as well as micrococci, diplococci, streptococci, spirilla, and protozoa. Saprophytic inhabitants of the oral cavity can cause caries.

Table 41 Criteria for normal microflora

The stomach and small intestine contain relatively few microbes, which is explained by the bactericidal effect of gastric juice and bile. However, in some cases, lactobacilli, acid-resistant yeasts, and streptococci are detected in healthy people. In pathological conditions of the digestive organs (chronic gastritis with secretory insufficiency, chronic enterocolitis, etc.), colonization of the upper parts of the small intestine by various microorganisms is observed. In this case, there is a violation of fat absorption, steatorrhea and megaloplastic anemia develop. The transition through the Bauhinian valve into the large intestine is accompanied by significant quantitative and qualitative changes.

The total number of microorganisms is 1-5x10n microbes per 1 g of content.

In the microflora of the colon, anaerobic bacteria (bifidobacteria, bacteroides, various spore forms) make up more than 90% of the total number of microbes. Aerobic bacteria represented by E. Coli, lactobacilli and others average 1-4%, and staphylococcus, clostridia, Proteus and yeast-like fungi do not exceed 0.01-0.001%. Qualitatively, the microflora of feces is similar to the microflora of the large intestine cavity. Their quantity is determined in 1 g of feces (see table 41).

Normal intestinal microflora undergoes changes depending on nutrition, age, living conditions and a number of other factors. Primary colonization of the child's intestinal tract by microbes occurs during birth with Doderlein bacilli, which belong to the lactic acid flora. In the future, the nature of the microflora depends significantly on nutrition. For children who are breastfed from 6-7 days, bifid flora is prevalent.

Bifidobacteria are found in 1 g of feces and constitute up to 98% of the total intestinal microflora. The development of bifid flora is supported by lactose and bifidus factor I and II contained in breast milk. Bifidobacteria, lactobacilli are involved in the synthesis of vitamins (group B, PP, folic acid) and essential amino acids, promote the absorption of calcium salts, vitamin D, iron, inhibit the growth and reproduction of pathogenic and putrefactive microorganisms, regulate the motor-evacuation function of the colon, activate local protective intestinal reactions. In children of the first year of life who are bottle-fed, the content of bifid flora drops to 106 or less; Escherichia coli, acidophilus bacilli, and enterococci predominate. The frequent occurrence of intestinal disorders in such children is explained by the replacement of bifid flora with other bacteria.

The microflora of toddlers is characterized by a high content of E. coli and enterococci; the aerobic flora is dominated by bifidobacteria.

In older children, the microflora in its composition is close to the microflora of adults.

Normal microflora is well adapted to the conditions of existence in the intestines and successfully competes with other bacteria coming from outside. High antagonistic activity of bifido-, lactoflora and normal Escherichia coli is manifested against the causative agents of dysentery, typhoid fever, anthrax, diphtheria bacillus, Vibrio cholerae, etc. Intestinal saprophytes produce a variety of bactericidal and bacteriostatic substances, including types of antibiotics.

The immunizing property of normal microflora is of great importance for the body. Escherichia, along with enterococci and a number of other microorganisms, cause constant antigenic irritation of the local immune system, maintaining it in a physiologically active state (Hazenson JI. B., 1982), which promotes the synthesis of immunoglobulins that prevent the penetration of pathogenic enterobacteria into the mucous membrane.

Intestinal bacteria are directly involved in biochemical processes, the decomposition of bile acids and the formation of stercobilin, coprosterol, and deoxycholic acid in the colon. All this has a beneficial effect on metabolism, peristalsis, absorption and formation of feces. When the normal microflora changes, the functional state of the colon is disrupted.

The intestinal microflora is in close connection with the macroorganism, performs an important non-specific protective function, and helps maintain the constancy of the biochemical and biological environment of the intestinal tract. At the same time, normal microflora is a highly sensitive indicator system that responds with pronounced quantitative and qualitative changes to changes in environmental conditions in its habitat, which is manifested by dysbacteriosis.

Reasons for changes in normal intestinal microflora

Normal intestinal microflora can only exist in a normal physiological state of the body. With various adverse effects on the macroorganism, a decrease in its immunological status, pathological conditions and processes in the intestines, changes occur in the microflora of the gastrointestinal tract. They can be short-term and disappear spontaneously after eliminating the external factor causing the adverse effects, or they can be more pronounced and persistent.

GIT MICROFLORA

MICROFLORA OF THE GASTROINTESTINAL TRACT

BASIC FUNCTIONS OF NORMAL MICROFLORA OF THE INTESTINAL TRACT

Normal microflora (normoflora) of the gastrointestinal tract is a necessary condition for the life of the body. The microflora of the gastrointestinal tract in the modern understanding is considered as the human microbiome.

Normal flora (microflora in a normal state) or Normal state of microflora (eubiosis) is a qualitative and quantitative ratio of diverse populations of microbes in individual organs and systems, maintaining the biochemical, metabolic and immunological balance necessary to maintain human health. The most important function of microflora is its participation in the formation of the body's resistance to various diseases and ensuring the prevention of colonization of the human body by foreign microorganisms.

In any microbiocenosis, including intestinal, there are always permanently inhabiting species of microorganisms - 90% belonging to the so-called. obligate microflora (synonyms: main, autochthonous, indigenous, resident, obligate microflora), which has a leading role in maintaining the symbiotic relationship between the macroorganism and its microbiota, as well as in the regulation of intermicrobial relationships, and there are also additional (accompanying or facultative microflora) - about 10% and transient (random species, allochthonous, residual microflora) - 0.01%

Those. the entire intestinal microflora is divided into:

• obligate- home or obligatory microflora, about 90% of the total number of microorganisms. The obligate microflora mainly includes anaerobic saccharolytic bacteria: bifidobacteria (Bifidobacterium), propionic acid bacteria (Propionibacterium), bacteroides (Bacteroides), lactobacilli (Lactobacillus);
• optional- accompanying or additional microflora, makes up about 10% of the total number of microorganisms. Facultative representatives of the biocenosis: Escherichia (Escherichia coli), Enterococcus, Fusobacterium, Peptostreptococcus, Clostridium, Eubacterium, etc., of course, have a number of physiological functions that are important for the biotope and the body as a whole. However, the predominant part of them is represented by opportunistic species, which, with a pathological increase in populations, can cause serious infectious complications.
• residual - transient microflora or random microorganisms, less than 1% of the total number of microorganisms. The residual microflora is represented by various saprophytes (staphylococci, bacilli, yeast fungi) and other opportunistic representatives of enterobacteria, which include intestinal bacteria: Klebsiella, Proteus, Citrobacter, Enterobacter, etc. Transient microflora (Citrobacter, Enterobacter, Proteus, Klebsiella, Morganella, Serratia, Hafnia, Kluyvera, Staphylococcus, Pseudomonas, Bacillus, yeast and yeast-like fungi, etc.), mainly consists of individuals introduced from outside. Among them, there may be variants with a high aggressive potential, which, when the protective functions of the obligate microflora are weakened, can increase populations and cause the development of pathological processes.

The stomach contains little microflora, much more in the small intestine and especially much in the large intestine. It is worth noting that the absorption of fat-soluble substances, the most important vitamins and microelements occurs mainly in the jejunum. Therefore, the systematic inclusion in the diet of probiotic products and dietary supplements, which contain microorganisms that regulate intestinal absorption processes, becomes a very effective tool in the prevention and treatment of nutritional diseases.

Intestinal absorption is the process of the entry of various compounds through a layer of cells into the blood and lymph, as a result of which the body receives all the substances it needs.

The most intensive absorption occurs in the small intestine. Due to the fact that small arteries branching into capillaries penetrate into each intestinal villi, absorbed nutrients easily penetrate into the body fluids. Glucose and proteins broken down into amino acids are absorbed into the blood mediocre. Blood carrying glucose and amino acids is sent to the liver, where carbohydrates are deposited. Fatty acids and glycerol - a product of fat processing under the influence of bile - are absorbed into the lymph and from there enter the circulatory system.

In the figure on the left (diagram of the structure of the villi of the small intestine): 1 - cylindrical epithelium, 2 - central lymphatic vessel, 3 - capillary network, 4 - mucous membrane, 5 - submucous membrane, 6 - muscular plate of the mucous membrane, 7 - intestinal gland, 8 - lymphatic channel.

One of the significance of the microflora of the large intestine is that it is involved in the final decomposition of undigested food residues. In the large intestine, digestion ends with the hydrolysis of undigested food residues. During hydrolysis in the large intestine, enzymes that come from the small intestine and enzymes from intestinal bacteria are involved. Absorption of water, mineral salts (electrolytes), breakdown of plant fiber, and formation of feces occurs.

Microflora plays a significant (!) role in peristalsis, secretion, absorption and cellular composition of the intestine. Microflora is involved in the decomposition of enzymes and other biologically active substances. Normal microflora provides colonization resistance - protection of the intestinal mucosa from pathogenic bacteria, suppressing pathogenic microorganisms and preventing infection of the body. Bacterial enzymes break down fiber fibers that are undigested in the small intestine. Intestinal flora synthesizes vitamin K and B vitamins, a number of essential amino acids and enzymes necessary for the body. With the participation of microflora in the body, the exchange of proteins, fats, carbons, bile and fatty acids, cholesterol occurs, procarcinogens (substances that can cause cancer) are inactivated, excess food is utilized and feces are formed. The role of normal flora is extremely important for the host organism, which is why its disruption (dysbacteriosis) and the development of dysbiosis in general leads to serious diseases of a metabolic and immunological nature.

The composition of microorganisms in certain parts of the intestine depends on many factors: lifestyle, nutrition, viral and bacterial infections, as well as drug treatment, especially antibiotics. Many gastrointestinal diseases, including inflammatory diseases, can also disrupt the intestinal ecosystem. The result of this imbalance is common digestive problems: bloating, indigestion, constipation or diarrhea, etc.

The intestinal microflora is an incredibly complex ecosystem. One individual has at least 17 families of bacteria, 50 genera, species and an indefinite number of subspecies. The intestinal microflora is divided into obligate (microorganisms that are constantly part of the normal flora and play an important role in metabolism and anti-infective protection) and facultative (microorganisms that are often found in healthy people, but are opportunistic, i.e. capable of causing diseases when reduced resistance of the macroorganism). The dominant representatives of obligate microflora are bifidobacteria.

Table 1 shows the most well-known functions of the intestinal microflora (microbiota), while its functionality is much broader and is still being studied

BARRIER ACTION AND IMMUNE PROTECTION

It is difficult to overestimate the importance of microflora for the body. Thanks to the achievements of modern science, it is known that normal intestinal microflora takes part in the breakdown of proteins, fats and carbohydrates, creates conditions for optimal digestion and absorption processes in the intestine, takes part in the maturation of cells of the immune system, which ensures enhanced protective properties of the body, etc. . The two most important functions of normal microflora are: barrier against pathogenic agents and stimulation of the immune response:

BARRIER ACTION. Intestinal microflora has a suppressive effect on the proliferation of pathogenic bacteria and thus prevents pathogenic infections.

The process of attachment of microorganisms to epithelial cells includes complex mechanisms. Bacteria of the intestinal microflora suppress or reduce the adhesion of pathogenic agents through competitive exclusion.

For example, bacteria of the parietal (mucosal) microflora occupy certain receptors on the surface of epithelial cells. Pathogenic bacteria that could bind to the same receptors are eliminated from the intestines. Thus, intestinal bacteria prevent the penetration of pathogenic and opportunistic microbes into the mucous membrane (in particular, propionic acid bacteria P. freudenreichii have fairly good adhesive properties and attach to intestinal cells very reliably, creating the aforementioned protective barrier. Also, bacteria of permanent microflora help maintain intestinal peristalsis and the integrity of the intestinal mucosa. Thus, bacteria - commensals of the colon during the catabolism of carbohydrates indigestible in the small intestine (so-called dietary fiber) form short-chain fatty acids ( SCFA, short-chain fatty acids), such as acetate, propionate and butyrate, which support the barrier functions of the mucin layer of mucus (increase the production of mucins and the protective function of the epithelium).

IMMUNE INTESTINAL SYSTEM. More than 70% of immune cells are concentrated in the human intestine. The main function of the intestinal immune system is to protect against bacteria entering the blood. The second function is the elimination of pathogens (pathogenic bacteria). This is ensured by two mechanisms: congenital (inherited by the child from the mother; people have antibodies in their blood from birth) and acquired immunity (appears after foreign proteins enter the blood, for example, after suffering an infectious disease).

Upon contact with pathogens, the body's immune defense is stimulated. When interacting with Toll-like receptors, the synthesis of various types of cytokines is triggered. Intestinal microflora influence specific accumulations of lymphoid tissue. Due to this, the cellular and humoral immune response is stimulated. Cells of the intestinal immune system actively produce secretory immunolobulin A (LgA), a protein that is involved in providing local immunity and is the most important marker of the immune response.

ANTIBIOTIC-LIKE SUBSTANCES. Also, the intestinal microflora produces many antimicrobial substances that inhibit the reproduction and growth of pathogenic bacteria. With dysbiotic disorders in the intestines, not only an excessive growth of pathogenic microbes is observed, but also a general decrease in the body’s immune defense. Normal intestinal microflora plays a particularly important role in the life of newborns and children.

Thanks to the production of lysozyme, hydrogen peroxide, lactic, acetic, propionic, butyric and a number of other organic acids and metabolites that reduce the acidity (pH) of the environment, bacteria of normal microflora effectively fight pathogens. In this competitive struggle of microorganisms for survival, antibiotic-like substances such as bacteriocins and microcins occupy a leading place. Below in the figure Left: Colony of acidophilus bacillus (x 1100), Right: Destruction of Shigella flexneri (a) (Shigella flexneri is a type of bacteria that causes dysentery) under the influence of bacteriocin-producing cells of acidophilus bacillus (x 60000)

HISTORY OF STUDYING THE COMPOSITION OF GIT MICROFLORA

The history of studying the composition of the microflora of the gastrointestinal tract (GIT) began in 1681, when the Dutch researcher Antonie Van Leeuwenhoek first reported his observations of bacteria and other microorganisms found in human feces, and hypothesized the coexistence of various types of bacteria in the gastrointestinal tract. -intestinal tract.

In 1850, Louis Pasteur developed the concept of the functional role of bacteria in the fermentation process, and the German physician Robert Koch continued research in this direction and created a technique for isolating pure cultures that allows the identification of specific bacterial strains, which is necessary to distinguish between pathogenic and beneficial microorganisms.

In 1886, one of the founders of the doctrine of intestinal infections, F. Esherich, first described Escherichia coli (Bacterium coli communae). Ilya Ilyich Mechnikov in 1888, working at the Louis Pasteur Institute, argued that the human intestine contains a complex of microorganisms that have an “autointoxication effect” on the body, believing that the introduction of “healthy” bacteria into the gastrointestinal tract can modify the action of intestinal microflora and counteract intoxication . The practical implementation of Mechnikov's ideas was the use of acidophilic lactobacilli for therapeutic purposes, which began in the USA in 1920–1922. Domestic researchers began to study this issue only in the 50s of the 20th century.

In 1955 Peretz L.G. showed that E. coli in healthy people is one of the main representatives of normal microflora and plays a positive role due to its strong antagonistic properties against pathogenic microbes. Research on the composition of the intestinal microbiocenosis, its normal and pathological physiology, and the development of ways to positively influence the intestinal microflora, begun more than 300 years ago, continues to this day.

HUMAN AS A HABITAT FOR BACTERIA

The main biotopes are: gastrointestinal tract (oral cavity, stomach, small intestine, large intestine), skin, respiratory tract, urogenital system. But the main interest for us here is the organs of the digestive system, because... the bulk of various microorganisms live there.

The microflora of the gastrointestinal tract is the most representative; the mass of the intestinal microflora in an adult is more than 2.5 kg, and the number is up to CFU/g. Previously, it was believed that the microbiocenosis of the gastrointestinal tract includes 17 families, 45 genera, more than 500 species of microorganisms (the latest data - about 1500 species) are constantly being adjusted.

Taking into account new data obtained from studying the microflora of various gastrointestinal biotopes using molecular genetic methods and gas-liquid chromatography-mass spectrometry, the total genome of gastrointestinal bacteria contains 400 thousand genes, which is 12 times the size of the human genome.

The parietal (mucosal) microflora of 400 different sections of the gastrointestinal tract, obtained during endoscopic examination of various sections of the intestines of volunteers, was analyzed for homology of sequenced 16S rRNA genes.

As a result of the study, it was shown that the parietal and luminal microflora includes 395 phylogenetically distinct groups of microorganisms, of which 244 are completely new. Moreover, 80% of new taxa identified during molecular genetic research belong to uncultivated microorganisms. Most of the putative new phylotypes of microorganisms are representatives of the genera Firmicutes and Bacteroides. The total number of species is approaching 1500 and requires further clarification.

The gastrointestinal tract communicates through the sphincter system with the external environment of the world around us and, at the same time, through the intestinal wall, with the internal environment of the body. Thanks to this feature, the gastrointestinal tract has its own environment, which can be divided into two separate niches: chyme and mucous membrane. The human digestive system interacts with various bacteria, which can be designated as “endotrophic microflora of the human intestinal biotope.” Human endotrophic microflora is divided into three main groups. The first group includes eubiotic indigenous or eubiotic transient microflora that is beneficial to humans; the second - neutral microorganisms that are constantly or periodically sown from the intestines, but do not affect human life; the third group includes pathogenic or potentially pathogenic bacteria (“aggressive populations”).

CAVITY AND WALL MICROBIOTOPE OF THE GASTROINTESTINAL TRACT

In microecological terms, the gastrointestinal biotope can be divided into tiers (oral cavity, stomach, intestinal sections) and microbiotopes (cavity, parietal and epithelial).

The ability to apply in the parietal microbiotope, i.e. Histadhesiveness (the property of being fixed and colonizing tissues) determines the essence of the transient or indigeneity of bacteria. These signs, as well as belonging to a eubiotic or aggressive group, are the main criteria characterizing a microorganism interacting with the gastrointestinal tract. Eubiotic bacteria participate in the creation of colonization resistance of the body, which is a unique mechanism of the anti-infective barrier system.

The cavity microbiotope throughout the gastrointestinal tract is heterogeneous; its properties are determined by the composition and quality of the contents of a particular tier. The tiers have their own anatomical and functional characteristics, so their contents differ in the composition of substances, consistency, pH, speed of movement and other properties. These properties determine the qualitative and quantitative composition of the cavity microbial populations adapted to them.

The parietal microbiotope is the most important structure that limits the internal environment of the body from the external one. It is represented by mucous deposits (mucus gel, mucin gel), a glycocalyx located above the apical membrane of enterocytes and the surface of the apical membrane itself.

The wall microbiotope is of the greatest (!) interest from the point of view of bacteriology, since it is in it that beneficial or harmful interactions with bacteria for humans occur - what we call symbiosis.

It should be noted that in the intestinal microflora there are 2 types:

• mucosal (M) flora - mucosal microflora interacts with the mucous membrane of the gastrointestinal tract, forming a microbial-tissue complex - microcolonies of bacteria and their metabolites, epithelial cells, goblet cell mucin, fibroblasts, immune cells of Peyre's patches, phagocytes, leukocytes, lymphocytes, neuroendocrine cells;
• luminal (L) flora - luminal microflora is located in the lumen of the gastrointestinal tract and does not interact with the mucous membrane. The substrate for its life activity is indigestible dietary fiber, on which it is fixed.

Today it is known that the microflora of the intestinal mucosa is significantly different from the microflora of the intestinal lumen and feces. Although every adult's intestine is inhabited by a certain combination of predominant bacterial species, the composition of the microflora can change depending on lifestyle, diet and age. A comparative study of the microflora in adults who are genetically related to one degree or another revealed that the composition of the intestinal microflora is influenced more by genetic factors than by nutrition.

The number of microorganisms of mucosal and luminal microflora in different parts of the digestive tract.

Note to the figure: FOG - fundus of the stomach, AOG - antrum of the stomach, duodenum - duodenum (

In the gastrointestinal tract – The human intestinal tract contains obligate (main microflora), facultative (opportunistic and saprophytic microflora) and transient microflora (microorganisms accidentally entering the gastrointestinal tract).

In the esophagus and stomach, transient microflora is usually detected, entering them with food or from the oral cavity. Despite the entry of a large number of microbes into the stomach, in healthy people a small number of microorganisms are normally detected in the stomach (less than 10 3 CFU/ml). This is due to the acidic pH value of the stomach contents and the bactericidal properties of gastric juice, which reliably protects a person from the penetration of pathogenic and opportunistic bacteria into the intestines. Gastric juice contains mainly acid-fast bacteria – lactobacilli, yeast fungi. In some people, streptococci are detected in it, S. ventriculus, B. subtilis, anaerobic gram-positive cocci.

In the thickness of the gastric mucosa, anaerobes veillonella, bacteroides, and peptococci are found.

In a study of healthy children aged 8 – For 15 years, staphylococci, streptococci, enterococci, corynebacteria, peptococci, lactobacilli and propionibacteria were identified in the antral mucosa of the stomach. Microbiological examination of stomach contents is carried out relatively rarely.

The number and composition of microbes in the small intestine varies depending on the part of the intestine. The total number of microbes in the small intestine is no more than 10 4 – 10 5 CFU/ml contents. The low concentration of microbes is due to the action of bile, the presence of pancreatic enzymes, and intestinal peristalsis, which ensures the rapid removal of microbes to the distal intestine; the production of immunoglobulins by mucosal cells, the state of the intestinal epithelium and mucus secreted by intestinal goblet cells containing microbial growth inhibitors. The microflora of the small intestine is represented predominantly by gram-positive facultative – anaerobic and anaerobic bacteria (enterococci, lactobacilli, bifidobacteria), yeast-like fungi, less common bacteroides and veillonella, and extremely rarely enterobacteria. After eating, the number of microbes in the small intestine may increase significantly, but then in a short time it quickly returns to its original level. In the lower parts of the small intestine (in the ileum), the number of microbes increases and can reach 10 7 CFU/ml of contents.

In the large intestine, the gram-positive flora changes to gram-negative. The number of obligate anaerobes begins to exceed the number of facultative anaerobes. Representatives of microbes characteristic of the large intestine appear.

The growth and development of microbes in the large intestine is facilitated by the absence of digestive enzymes, the presence of a large amount of nutrients, the presence of food for a long time, the structural features of the mucous membrane and, in particular, the mucous membranes of the large intestine. They determine the organ tropism of some types of anaerobic bacteria, which, as a result of their vital activity, form products used by facultative anaerobic flora, which in turn create conditions for the life of obligate anaerobes.

More than 400 species of different microbes are present in the human large intestine, with the number of anaerobes being 100 – 1000 times the number of facultative anaerobes. Obligate anaerobes make up 90-95% of the total composition. They are represented by bifidobacteria, lactobacilli, bacteroides, veillonella, peptostreptococci, clostridia and fusobacteria (Fig. 1)

The share of other microorganisms accounts for 0.1 – 0.01% is residual microflora: enterobacteria (Proteus, Klebsiella, Serration), enterococci, staphylococci, streptococci, bacilli, yeast fungi (Fig. 3). Opportunistic amoebas, Trichomonas, and some types of intestinal viruses can live in the intestines.

B

Figure 1. Lactobacilli (A) and bifidobacteria (B).

In the human large intestine, M-mucosal microflora is isolated - microbes that live in the thickness of the mucous membrane. The number of microbes in the thickness of the mucosa is 10 8 CFU per gram of intestinal tissue. Some authors call mucosal microflora – "bacterial turf".

Microbes living in the lumen of the human intestine are called P – microflora (luminal or cavity). The number of microbes in human feces reaches 10 12 CFU/g. contents and makes up 1/3 of human fecal matter. Facultative anaerobes account for 5-10% of the microflora of the large intestine. It contains: Escherichia coli and enterococci (Fig. 2)

The obligate permanent microflora of the human intestine is represented mainly by bifidobacteria, lactobacilli, E. coli and enterococci. Facultative flora is less common, it is represented by other anaerobic and facultative – anaerobic bacteria.

Dysbacteriosis (dysbiosis, dismicrobiocenosis) of the intestine – qualitative and quantitative changes in microflora. Dysbacteriosis is accompanied by a decrease in obligate anaerobic flora (bifidobacteria and lactobacilli) and an increase in conditionally pathogenic microflora, which are normally absent or found in small quantities (staphylococci, pseudomonads, yeast-like fungi, proteas, etc.). The appearance of dysbiosis can lead to immunological disorders with the possible development of gastrointestinal disorders.

The development of dysbiosis in humans is facilitated by exogenous and endogenous factors: infectious diseases of the digestive system, diseases of the gastrointestinal tract, liver, oncological pathology, allergic diseases. Changes in microflora are facilitated by the use of antibiotics, hormones, immunosuppressants, cytostatics, psychotropic, laxatives and contraceptives, and exposure to industrial poisons and pesticides. The composition of microflora is greatly influenced by the season of the year, human nutrition, stress, smoking, drug addiction, and alcoholism.

The appearance of dysbacteriosis in newborns can be caused by bacterial vaginosis and mastitis in the mother, resuscitation measures, late breastfeeding, long stay in the maternity hospital, immaturity of intestinal motor function, intolerance to breast milk, maladsorption syndrome.

In infancy, the development of dysbacteriosis is promoted by: early artificial feeding, frequent acute respiratory viral infections, rickets, anemia, malnutrition, allergic and neuropsychiatric diseases.

BASIC FUNCTIONS OF NORMAL MICROFLORA OF THE INTESTINAL TRACT

Normal microflora (normoflora) of the gastrointestinal tract is a necessary condition for the life of the body. The microflora of the gastrointestinal tract in the modern understanding is considered as the human microbiome.

Normoflora(microflora in normal condition) or Normal state of microflora (eubiosis) is a qualitative and quantitative ratio of diverse microbial populations of individual organs and systems, maintaining the biochemical, metabolic and immunological balance necessary to maintain human health. The most important function of microflora is its participation in the formation of the body's resistance to various diseases and ensuring the prevention of colonization of the human body by foreign microorganisms.

In any microbiocenosis, including intestinal, there are always permanently inhabiting species of microorganisms - 90% belonging to the so-called. obligate microflora ( synonyms: main, autochthonous, indigenous, resident, obligate microflora), which has a leading role in maintaining the symbiotic relationship between the macroorganism and its microbiota, as well as in the regulation of intermicrobial relationships, and there are also additional (accompanying or facultative microflora) - about 10% and transient ( random species, allochthonous, residual microflora) - 0.01%

Those. the entire intestinal microflora is divided into:

• obligate — home orobligatory microflora , about 90% of the total number of microorganisms. The obligate microflora mainly includes anaerobic saccharolytic bacteria: bifidobacteria (Bifidobacterium), propionic acid bacteria (Propionibacterium), bacteroides (Bacteroides), lactobacilli (Lactobacillus);
• optional — accompanying oradditional microflora, makes up about 10% of the total number of microorganisms. Facultative representatives of the biocenosis: Escherichia ( coli and - Escherichia), enterococci (Enterococcus), fusobacterium (Fusobacterium), peptostreptococci (Peptostreptococcus), clostridia (Clostridium) eubacteria (Eubacterium) and others, of course, have a number of physiological functions that are important for the biotope and the organism as a whole. However, the predominant part of them is represented by opportunistic species, which, with a pathological increase in populations, can cause serious infectious complications.
• residual — transient microflora or random microorganisms, less than 1% of the total number of microorganisms. The residual microflora is represented by various saprophytes (staphylococci, bacilli, yeast fungi) and other opportunistic representatives of enterobacteria, which include intestinal bacteria: Klebsiella, Proteus, Citrobacter, Enterobacter, etc. Transient microflora (Citrobacter, Enterobacter, Proteus, Klebsiella, Morganella, Serratia, Hafnia, Kluyvera, Staphylococcus, Pseudomonas, Bacillus, yeast and yeast-like fungi, etc.), mainly consists of individuals introduced from outside. Among them, there may be variants with a high aggressive potential, which, when the protective functions of the obligate microflora are weakened, can increase populations and cause the development of pathological processes.

The stomach contains little microflora, much more in the small intestine and especially much in the large intestine. It is worth noting that suction fat-soluble substances, the most important vitamins and microelements occur mainly in the jejunum. Therefore, the systematic inclusion in the diet of probiotic products and dietary supplements, which contain microorganisms that regulate intestinal absorption processes, becomes a very effective tool in the prevention and treatment of nutritional diseases.

Intestinal absorption- this is the process of the entry of various compounds through a layer of cells into the blood and lymph, as a result of which the body receives all the substances it needs.

The most intensive absorption occurs in the small intestine. Due to the fact that small arteries branching into capillaries penetrate into each intestinal villi, absorbed nutrients easily penetrate into the body fluids. Glucose and proteins broken down into amino acids are absorbed into the blood mediocre. Blood carrying glucose and amino acids is sent to the liver, where carbohydrates are deposited. Fatty acids and glycerol - a product of fat processing under the influence of bile - are absorbed into the lymph and from there enter the circulatory system.

In the picture on the left(diagram of the structure of the villi of the small intestine): 1 - columnar epithelium, 2 - central lymphatic vessel, 3 - capillary network, 4 - mucous membrane, 5 - submucous membrane, 6 - muscular plate of the mucous membrane, 7 - intestinal gland, 8 - lymphatic channel .

One of the meanings of microflora colon is that it participates in the final decomposition of undigested food residues. In the large intestine, digestion ends with the hydrolysis of undigested food residues. During hydrolysis in the large intestine, enzymes that come from the small intestine and enzymes from intestinal bacteria are involved. Absorption of water, mineral salts (electrolytes), breakdown of plant fiber, and formation of feces occurs.

Microflora plays a significant (!) role in peristalsis, secretion, absorption and cellular composition of the intestine. Microflora is involved in the decomposition of enzymes and other biologically active substances. Normal microflora provides colonization resistance - protection of the intestinal mucosa from pathogenic bacteria, suppressing pathogenic microorganisms and preventing infection of the body. Bacterial enzymes break down fiber fibers that are undigested in the small intestine. Intestinal flora synthesizes vitamin K and B vitamins, a number of essential amino acids and enzymes necessary for the body. With the participation of microflora in the body, the exchange of proteins, fats, carbons, bile and fatty acids, cholesterol occurs, procarcinogens (substances that can cause cancer) are inactivated, excess food is utilized and feces are formed. The role of normal flora is extremely important for the host organism, which is why its disruption (dysbacteriosis) and the development of dysbiosis in general leads to serious diseases of a metabolic and immunological nature.

The composition of microorganisms in certain parts of the intestine depends on many factors: lifestyle, nutrition, viral and bacterial infections, as well as drug treatment, especially antibiotics. Many gastrointestinal diseases, including inflammatory diseases, can also disrupt the intestinal ecosystem. The result of this imbalance is common digestive problems: bloating, indigestion, constipation or diarrhea, etc.

The intestinal microflora is an incredibly complex ecosystem. One individual has at least 17 families of bacteria, 50 genera, 400-500 species and an indefinite number of subspecies. The intestinal microflora is divided into obligate (microorganisms that are constantly part of the normal flora and play an important role in metabolism and anti-infective protection) and facultative (microorganisms that are often found in healthy people, but are opportunistic, i.e. capable of causing diseases when reduced resistance of the macroorganism). The dominant representatives of obligate microflora are bifidobacteria.

Table 1 shows the most well-known functions of the intestinal microflora (microbiota), while its functionality is much broader and is still being studied

Intestinal bacteria, probiotics and prospects for their use in the treatment of gastrointestinal diseases

Department of Propaedeutics of Internal Diseases, Faculty of Medicine, MMA named after. THEM. Sechenova, Moscow The compositional features and role of intestinal symbiont bacteria in maintaining health are considered. The correctness of using the term “dysbacteriosis” in clinical practice is discussed; diseases and conditions that are often mistakenly interpreted as dysbacteriosis are indicated. A brief overview of diseases for which the effectiveness of some probiotics has been confirmed by the results of comparative studies is provided. Indications for the use of the modern combined probiotic drug Linex, its advantages and dosage regimens are presented.

The history of studying the role of intestinal microflora in maintaining human health dates back to the end of the 19th century, when the concept of disease as a consequence of intestinal “autointoxication” developed.

But even today we have to admit that we still know little about the interaction between our body and the bacteria inhabiting it, and it is very difficult to assess the composition of the microflora inhabiting the gastrointestinal tract (GIT) from the standpoint of “norm” and “pathology”.

Composition and physiological significance of intestinal microflora

More than 400 species of microorganisms live in the human gastrointestinal tract. The content of colony-forming units (CFU) in 1 ml of intraluminal contents increases from 10 2–3 to 10 11–12 as it moves from the stomach to the colon. At the same time, the proportion of anaerobic microorganisms increases and their oxidative potential decreases.

Intestinal bacteria are represented by the main (dominant, or resident), accompanying and residual populations.

The dominant population consists mainly of bacteria from the Lactobacillus, Bifidobacteria and Bacteroides families.

The associated population is represented by Escherichia coli, eubacteria, fusobacteria, enterococci and peptococci.

The residual population includes yeast-like fungi, bacilli, clostridia, Proteus, etc. Some of these microorganisms have more or less pronounced pathogenic properties. It is generally accepted that in a healthy person, no more than 15% of intestinal microbes have pathogenic or opportunistic characteristics.

In the upper gastrointestinal tract, the composition of the microflora is similar to that of the oropharynx; a significant proportion of it is represented by streptococci. In the distal direction, the content of lactobacilli gradually increases, and in the large intestine bifidobacteria predominate.

According to modern concepts, the main role in maintaining the normal physiological state of the gastrointestinal microflora is played by bacteria of the Lactobacillus and Bifidobacteria families, which are gram-positive, non-spore-forming anaerobes that do not have pathogenic properties. An important characteristic of these microorganisms is the saccharolytic type of metabolism. In the process of fermentation of carbohydrates under the action of enzymes of lactobacilli and bifidobacteria, short-chain fatty acids are formed - lactic, acetic, butyric, propionic. In the presence of these acids, the development of opportunistic strains, which for the most part have a proteolytic type of metabolism, is inhibited. Suppression of proteolytic strains is accompanied by inhibition of putrefactive processes and suppression of the formation of ammonia, aromatic amines, sulfides, and endogenous carcinogens. Thanks to the production of fatty acids, the pH of the intestinal contents is regulated.

Short-chain fatty acids play an important role in regulating metabolism. Entering the systemic circulation, they provide up to 20% of the body's daily energy needs, and also serve as the main energy supplier for the epithelium of the intestinal wall.

Butyric and propionic acids increase mitotic activity and regulate epithelial differentiation. Lactic and propionic acids regulate calcium absorption. Their role in the regulation of cholesterol metabolism and glucose metabolism in the liver is of great interest.

Lactobacilli and bifidobacteria synthesize amino acids, proteins, vitamins B1, B2, B6, B12, K, nicotinic and folic acids, substances with antioxidant activity.

Basic population bacteria play an important role in the digestion of milk components. Lactobacilli and enterococcus are capable of breaking down lactose and milk proteins. Phosphoprotein phosphatase secreted by bifidobacteria is involved in the metabolism of casein. All these processes take place in the small intestine.

Lactobacillus species inhabiting the intestines include: L. acidophilus, L. casei, L. bulgaricus, L. plantarum, L. salivarius, L. rhamnosus, L. reuteri. Among bifidobacteria, B. bifidum, B. longum, and B. infantis are distinguished.

Of the aerobic microorganisms belonging to the accompanying population, a serious role in the intestinal microbial biocenosis belongs to the non-hemolytic Escherichia coli, which produces vitamins (B1, B2, B6, B12, K, nicotinic, folic, pantothenic acids), participates in cholesterol metabolism, bilirubin, choline, bile and fatty acids, indirectly affects the absorption of iron and calcium.

As knowledge about the vital functions of intestinal microflora expands, the idea of ​​its important role in maintaining the tension of local and systemic immunity is becoming increasingly clear.

There are protective mechanisms in the intestines that prevent excessive reproduction and introduction of microflora. These include the integrity of the epithelium and the brush border (the distance between the microvilli of which is less than the size of the bacterium), the production of immunoglobulin A, the presence of bile, the presence of Peyer's patches, etc.

Thanks to the production of substances with antibacterial activity (bacteriocins, short-chain fatty acids, lactoferrin, lysozyme), normal microflora provides local protection against excessive proliferation of opportunistic microorganisms and the introduction of pathogenic microorganisms. The presence of a constant microbial irritant and contact with macrophages and lymphocytes in the area of ​​Peyer's patches provide sufficient tension of local immunity, the production of immunoglobulin A and high phagocytic activity. At the same time, constant contact with immune cells underlies immunological tolerance.

Components of intestinal bacteria penetrate the systemic bloodstream, thus maintaining the necessary degree of tension of systemic immunity and ensuring its “acquaintance” with the microflora of the environment.

However, even those intestinal bacteria that are considered non-pathogenic, without a distinct ability to adhere, invade, or produce toxins, if local defense mechanisms fail, are theoretically capable of causing damage to the intestinal wall, and possibly also systemic infection. Therefore, the prescription of medications based on intestinal bacteria (probiotics) should always be justified.

Causes of disturbances in the composition of intestinal microflora

The composition of the intestinal microbial population, even in a healthy person, is subject to variability and, apparently, reflects the body’s ability to adapt to dietary and lifestyle characteristics and climatic factors.

It should be recognized that the general concept of “dysbacteriosis,” which until recently was widely used to designate disturbances in the composition of the intestinal microflora, does not fully reflect the essence of such changes and does not allow one to clearly formulate a diagnosis and determine treatment tactics.

Thus, we can distinguish individual diseases and syndromes, which are often mistakenly interpreted as dysbacteriosis:

• bacterial overgrowth syndrome;
• antibiotic-associated diarrhea;
• Clostridium difficile infection (pseudomembranous colitis);
• irritable bowel syndrome;
• “travelers' diarrhea”;
• disaccharidase deficiency;
• intestinal candidiasis due to immunodeficiency states;
• staphylococcal enteritis, etc.

Each of these diseases has its own cause, certain risk factors, clinical picture, diagnostic criteria and treatment tactics. Of course, against the background of these diseases, secondary disturbances in the microbial composition of the intestine can develop.

Perhaps the most common syndrome in clinical practice is bacterial overgrowth, characterized by a decrease in the number of anaerobes (especially bifidobacteria), an increase in the total number of functionally inferior forms of E. coli (“lactose-,” “mannitol-,” “indole-negative”), and the content of hemolytic forms E. coli and creating conditions for the proliferation of Candida spp.

Bacterial overgrowth syndrome develops against the background of disorders of luminal or parietal digestion (congenital enzyme deficiency, pancreatitis, gluten enteropathy, enteritis), passage of intestinal contents (intestinal fistulas, “blind loops” of the intestine, diverticula, peristalsis disorders, intestinal obstruction); decrease in the protective properties of the mucous membrane (anacidic conditions, immunodeficiencies); iatrogenic effects on the intestinal microflora (use of corticosteroids, cytostatics, especially in weakened and elderly patients).

Excessive proliferation of bacteria is observed mainly in the small intestine, since the most favorable nutrient environment is created here. Manifestations of bacterial overgrowth syndrome, such as flatulence, rumbling, abdominal transfusion, loose stools, hypovitaminosis, weight loss, often come to the fore in the clinical picture of the main diseases listed above.

Tests confirming the presence of pathological disorders in the composition of microflora

As in the diagnosis of other diseases, adequate methods must be used to assess changes in the intestinal microflora.

Stool culture for dysbacteriosis, which is common in Russia, cannot be considered an informative test, especially since pathological changes in the microflora mainly affect the small intestine. This method is valuable from the point of view of excluding intestinal infections, as well as C. difficile infection.

Microbiological examination of culture of aspirate of the contents of the small intestine has a very high accuracy.

A breath test with 14C-xylose, hydrogen tests with lactulose and glucose can detect the presence of bacterial overgrowth in the intestines, but do not provide information about the composition of the microflora.

Determination of the spectrum of fatty acids in feces by gas-liquid chromatographic analysis makes it possible to approximately estimate the quantitative ratio of different types of intestinal bacteria.

At the beginning of the 20th century, the great Russian scientist I.I. Mechnikov. put forward the hypothesis that a high content of lactobacilli in the intestinal biocenosis is a necessary condition for human health and longevity. Mechnikov I.I. conducted experiments on the use of live cultures of bifidobacteria for medicinal purposes.

In subsequent years, the development of drugs based on microorganisms with beneficial properties, the so-called probiotics, continued.

As a potential therapeutic agent, lactobacilli initially received the most attention as the bacteria with the best studied beneficial properties. Since the 1920s L. acidophilus culture began to be used in the form of acidophilus milk for the treatment of gastrointestinal diseases accompanied by constipation. Since the 1950s Experience is accumulating in the use of L. acidophilus and other cultures to prevent antibiotic-associated diarrhea.

As microbiology developed, new information was obtained about the positive properties of bifidobacteria, E. coli, and non-toxigenic lactic acid streptococcus - Streptococcus (or Enterococcus) faecium. Certain strains of these microorganisms and their combinations began to be included in probiotic preparations.

When studying the ability of microbes to adhere to epithelial cells of the small intestine, it was shown that the use of microorganisms in combination increases their ability to attach to the brush border area.

The mechanisms of therapeutic action of probiotics include: suppression of the growth of pathogenic microorganisms, restoration of epithelial integrity, stimulation of the secretion of immunoglobulin A, suppression of the production of proinflammatory cytokines, normalization of metabolic processes.

The modern approach to the development of such drugs implies, firstly, the use of microorganisms in combinations and, secondly, their release in capsule form, allowing long-term storage at normal temperatures. Clinical experimental studies have shown that under the influence of gastric juice and bile, probiotics lose up to 90% of their activity before entering the intestines. Methods are being developed to increase the survival rate of bacteria - due to their immobilization on porous microcarriers and the inclusion of nutrient medium components in the preparation.

Despite the “theoretically” sound development of probiotic preparations, not all of them turn out to be effective in practice. To date, data from many open and blind controlled studies have been accumulated, the results of which have led to some conclusions about the prospects for the use of certain types of microorganisms for various intestinal diseases.

It has been shown that L. rhamnosus strain GG has the greatest effect in the treatment of infectious gastroenteritis in children, and E. faecium SF68 in adults.

According to some data, during the recovery period after viral gastroenteritis, it is advisable to prescribe drugs containing lactobacilli or their combinations with bifidobacteria and enterococcus; Subspecies of bifidobacteria contribute to the speedy resolution of bacterial intestinal infections.

The ability to reduce the incidence of antibiotic-associated diarrhea has been established for the following bacteria in probiotics:

• L. rhamnosus strain GG;
• combination of L. acidophilus and L. bulgaricus;
• E. faecium SF68;
• B. longum;
• combination of Lactobacillus and B. longum;
• medicinal yeast Saccharomyces boulardii.

To reduce the incidence of side effects of anti-Helicobacter therapy, simultaneous administration of probiotics containing L. rhamnosus and S. Boulardii, or a combination of L. acidophilus with Bifidobacterium lactis, is recommended.

A combination of L. acidophilus, L. Bulgaricus and Streptococcus thermophilus was effective in preventing the development of traveler's diarrhea.

According to a meta-analysis, a probiotic containing S. boulardii is most effective in treating recurrent C. Difficile infection (pseudomembranous colitis).

In irritable bowel syndrome, the effect of probiotics on the severity of symptoms such as bloating, pain, and overall symptoms was studied. The effectiveness of microorganisms E. faecium, L. plantarum, as well as the VSL#3 mixture (combination of Bifidobacterium breve, B. longum, B. infantis, L. acidophilus, L. plantarum, L. casei, L. bulgaricus, S. thermophilus) has been demonstrated , mixtures of L. acidophilus, L. plantarum and B. breve and mixtures of L. salivarius and B. infantis. However, these data were obtained on relatively small groups of patients, and therefore have not yet been reflected in international recommendations for the treatment of patients with irritable bowel syndrome.

There is an urgent question about the possibility of using probiotics for the treatment and prevention of exacerbations in chronic inflammatory bowel diseases - ulcerative colitis and Crohn's disease. Given the undoubted role of endogenous microflora in maintaining the integrity of the epithelium and controlling inflammation, as well as the potential toxicity of immunosuppressants used today, great hopes are placed on probiotics as “drugs of the future” in the treatment of inflammatory bowel diseases. Due to insufficient statistical material, the results of the studies do not yet allow us to develop generally accepted recommendations for the inclusion of probiotics in standard treatment regimens. However, very encouraging data have been obtained regarding the ability of the complex probiotic VSL#3 to reduce the relapse rate of Crohn's disease. In ulcerative colitis, the effect in terms of maintaining remission was demonstrated by E. coli Nissle 1917 and Lactobacillus GG; from the point of view of remission induction - very high doses of probiotic VSL#3.

It should be understood that the administration of probiotics is rarely effective in the absence of etiotropic and pathogenetic treatment of the underlying disease. Depending on the specific situation, surgical treatment may be required (for example, with afferent loop syndrome, interintestinal fistulas), the prescription of anti-inflammatory and antibacterial drugs, regulators of gastrointestinal motility (for example, with irritable bowel syndrome).

Many probiotic preparations are registered in Russia. However, the vast majority of them are not sufficiently modern and do not contain species and strains of microorganisms for which evidence-based comparative studies have been obtained. As experience has accumulated, there has been a trend towards the use of combined probiotics.

Characteristics and application of Linex

In recent years, in the practice of Russian gastroenterologists, Linex, a combination drug containing bacteria - representatives of the natural intestinal microflora: Bifidobacterium infantis v. liberorum, Lactobacillus acidophilus and non-toxigenic group D lactic acid streptococcus – Streptococcus (Enterococcus) faecium. As noted above, these types of bacteria have demonstrated clinical effectiveness in the treatment of a number of intestinal diseases and are among the microorganisms that have particular “hopes” for inclusion in the future in treatment regimens for chronic inflammatory bowel diseases. The cultures of microorganisms that make up Linex were obtained by growing on media with the addition of antibiotics, therefore they are resistant to most antibacterial agents and are able to multiply even under conditions of antibacterial therapy. The resistance of the resulting strains to antibiotics is so high that it persists after repeated inoculations of 30 generations, as well as in vivo. However, no transfer of antibacterial resistance genes to other types of microorganisms was observed. This is very important from the point of view of the consequences of using Linex: both while taking and after discontinuation of the drug, there is no danger of pathogenic bacteria and their own microflora developing resistance to antibiotics.

The therapeutic effect of Linex consists of temporarily replacing the functions of the patient’s own intestinal microflora in conditions of its suppression, in particular against the background of the use of antibiotics. The inclusion of lactobacilli, S. Faecium and bifidobacteria in Linex ensures the supply of “medicinal” microflora to different parts of the intestine in quantitatively and qualitatively balanced proportions.

In a placebo-controlled study involving 60 adult patients suffering from antibiotic-associated diarrhea or diarrhea of ​​unknown etiology, taking Linex within 3-5 days was accompanied by normalization of stool. In children, Linex has been demonstrated to be highly effective in preventing and treating established antibiotic-associated diarrhea.

The use of Linex against the background of Helicobacter eradication therapy improves the tolerability of antibiotics: it reduces the incidence of flatulence and diarrhea.

In the intestine, the microbial components of Linex not only have a eubiotic effect, but also perform all the functions of normal intestinal microflora: they participate in the synthesis of vitamins B1, B2, B3, B6, B12, H (biotin), PP, K, E, folic and ascorbic acids. By lowering the pH of the intestinal contents, they create favorable conditions for the absorption of iron, calcium, and vitamin D.

Lactobacilli and lactic acid streptococcus carry out enzymatic breakdown of proteins, fats and complex carbohydrates, including having a substitutive effect for lactase deficiency, which in most cases accompanies intestinal diseases.

Linex is produced in capsules containing at least 1.2×10 7 live lyophilized bacteria.

The pharmacokinetics of the drug has been little studied due to the fact that there are currently no pharmacokinetic models for studying complex biological substances in humans, consisting of components with different molecular weights.

Infants and children under 2 years old are prescribed Linex 1 capsule 3 times a day, children 2–12 years old – 1–2 capsules 3 times a day, children over 12 years old and adults – 2 capsules 3 times a day. The drug is taken after meals with a small amount of liquid. Do not drink hot drinks to avoid the death of living microflora.

Linex can be prescribed during pregnancy and breastfeeding. There are no reports of cases of Linex overdose.

Thus, probiotics, especially their combination preparations, are gradually occupying an increasingly stronger place in gastroenterology.

As the evidence base accumulates, they may provide doctors with a way to treat the patient, skillfully influencing his symbiosis with the world of bacteria and minimal risk to the human body.

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Of the several hundred species of bacteria inhabiting the intestines, bifidobacteria and bacteroides predominate quantitatively, the proportion of which is 25% and 30%, respectively, in relation to the total number of anaerobic bacteria.

Before a baby is born, the gastrointestinal tract is not inhabited by bacteria. At the moment of birth, the baby’s intestines are rapidly colonized by bacteria that are part of the mother’s gastrointestinal and vaginal flora. As a result, a complex community of microorganisms is formed, consisting of bifidobacteria, lactobacilli, enterobacteria, clostridia and gram-positive cocci. After this, the composition of the microflora undergoes changes as a result of environmental influences, the most important of which is the child’s nutrition.

Already in 1900, German scientists proved that in breastfed children, the main component of the intestinal microflora is bifidobacteria. Such microflora, with a predominance of bifidobacteria, performs protective functions and contributes to the maturation of the mechanisms of the child’s immune system. On the contrary, in children who are bottle-fed, the number of bifidobacteria in the large intestine is much smaller and the species composition of the intestinal microflora is less diverse.

The species composition of bifidobacteria in the intestines of children who are exclusively breastfed is represented by numerous species and modifications. Colonies of some species of bifidobacteria that live in the intestines of adults are absent, which is fully consistent with the normal species composition of bifidobacteria in the intestines of infants.

At the same time, in children who are bottle-fed, the composition of the intestinal microflora is more diverse and contains the same amounts of bifidobacteria and bacteroides. The minimum components of the intestinal microflora in breast-fed children are lactobacilli and streptococci, and in bottle-fed children - staphylococci, Escherichia coli and clostridia. When solid foods are added to a child's diet, the number of bifidobacteria in the large intestine decreases in breast-fed children. At the age of 12 months in children, the composition and number of anaerobic (capable of developing without access to atmospheric oxygen) microorganisms in the large intestine approaches that of adults.

The human gastrointestinal tract is home to many bacteria, which, in fact, are “cohabitants” of their “host”. Strange as it may sound, the “host” organism needs microbial inhabitants just as much as they need its support.

The main part of microorganisms enters the lumen of the gastrointestinal tract from the oropharynx and with food.

More than 400 species of non-pathogenic aerobic (capable of developing in the atmosphere) and facultative anaerobic bacteria have been identified as part of the normal microflora of the gastrointestinal tract.

The intestinal biocenosis also includes a small number of conditionally pathogenic organisms that form the so-called “residual colony”: staphylococci, fungi, Proteus, etc.

The composition of the microflora is not the same throughout the gastrointestinal tract. In the upper and middle sections of the small intestine, the population of microorganisms is relatively small (at the beginning of the jejunum their content is no more than 100 microorganisms per 1 ml of contents) and includes predominantly gram-positive aerobic bacteria, a small number of anaerobic bacteria, yeast and fungi.

The highest content of microorganisms is observed in the large intestine. Here their concentration reaches 1010-1011 or more per 1 g of content.

The large intestine is home to the bulk of anaerobic microorganisms. The “main population” (about 70%) consists of anaerobic bacteria - bifidobacteria and bacteroides. Lactobacilli, Escherichia coli, and enterococci act as “accompanying” bacteria.

Bacteria inhabiting the lumen of the gastrointestinal tract perform a number of functions that are very important for the “host” organism.

Microbes play a vital role in intraluminal digestion, in particular, they participate in the digestion of dietary fiber (cellulose), the enzymatic breakdown of proteins, high-molecular carbohydrates, fats, and in the process of metabolism they produce a number of new substances useful to the body.

The main representative of the anaerobic intestinal microflora - bifidobacteria - produces amino acids, proteins, vitamins B1, B2, B6, B12, vikasol, nicotinic and folic acids. It has been suggested that some substances produced by bifidobacteria have special properties and help reduce the risk of colon cancer.

Among aerobic (air-dependent) microorganisms, the most important role in the processes of protein breakdown belongs to Escherichia coli, which has large and varied properties. Thus, one type of E. coli produces several vitamins (thiamine, riboflavin, pyridoxine, vitamins B12, K, nicotinic, folic, pantothenic acids), participates in the metabolism of cholesterol, bilirubin, choline, bile and fatty acids, and also affects the absorption of iron and calcium.

Protein processing products formed under the influence of microflora (indole, phenol, skatole) have a regulating effect on the normal functioning of the intestines.

Recently, the role of intestinal microflora in the formation of the body's immune system and protecting the body from diseases has been increasingly studied.

Representatives of normal intestinal microflora produce substances with antibacterial activity (such as bacteriokines and short-chain fatty acids, lactoferrin, lysozyme), which prevent the introduction of pathogenic microorganisms and suppress the excessive proliferation of conditionally pathogenic microflora. Escherichia coli, enterococci, bifidobacteria and lactobacilli have the most pronounced suppressive properties against pathogens.

The waste products of lactic acid bacteria (bifidobacteria, lactobacilli) and bacteroides are lactic, acetic, succinic, and formic acids. This ensures that the acidity of the intestinal contents is maintained at a level of 4.0-3.8, thereby inhibiting the growth and reproduction of pathogenic and putrefactive microorganisms in the gastrointestinal tract.

Initially limited ideas about the “local” protective role of intestinal microorganisms have expanded significantly in recent years. Modern medical science emphasizes the importance of continuous “communication” between the human body, the “host,” and its “cohabiting” bacteria. Through contact with bacteria through the mucous membrane and the constant penetration of a small amount of bacteria, their antigens and waste products into the circulatory system, human immunity is maintained, including, probably, the “tone” of antitumor defense is maintained.

The microflora of the gastrointestinal tract is actively involved in the chemical transformations of many substances of internal and external origin, in particular drugs. In the process of enterohepatic metabolism, substances coming from the intestinal lumen to the liver undergo complex biochemical processes, and many of them are then excreted again in the bile. In the intestinal lumen, under the influence of enzymes of the intestinal microflora, they undergo numerous changes, without which normal functioning of the body is impossible, after which they are reabsorbed and returned to the liver through the portal vein.

Mechanisms for maintaining normal “microbial balance” in the lumen of the gastrointestinal tract and inhibiting microbial growth include protective factors of the mucous membrane (anti-infective properties of gastric hydrochloric acid, mucus and antibody production), as well as normal peristaltic (contraction of intestinal muscles) activity of the intestine, during which Some bacteria are regularly removed from the body. The integrity of the brush border of enterocytes also acts as an important element of protection, since it acts as a “bacterial barrier” that prevents bacteria from contacting the cells of the mucous membrane.

The quantitative and qualitative composition of the intestinal microflora can change under the influence of various causes of both intraorganismal and external origin. However, this change should be considered secondary to the main cause.

Microflora of the gastrointestinal tract is a collection of microorganisms located in the lumen of the gastrointestinal tract. The most microflora-populated organ is the large intestine. In each section of the gastrointestinal tract, the microflora has a different quantitative and qualitative composition. The bulk of beneficial flora is located in the lower intestines. Microflora can be both beneficial and pathogenic, which is significant for the health of the human body, because balance is necessary, because beneficial microflora is primarily responsible for good human immunity.

Beneficial flora are bifidobacteria and lactobacilli, which are responsible for normal intestinal function. Also, these beneficial bacteria protect the human body from the penetration of pathogenic foreign microbes and toxins, and accordingly promote the absorption of vitamins, digestion processes, and also strengthen the immune system.

If the gastrointestinal tract is functioning normally, then the intestinal microflora has a balance of pathogenic and beneficial microbes and bacteria. There are not many bacteria in the human stomach, since it has an acidic environment, their number is 103 species, the largest number of bacteria is located in the large intestine, their number is about 1013 species. If the balance of beneficial and pathogenic bacteria is disturbed, this leads to dysbiosis and other diseases.

The role of microflora in the human body

The microflora of the digestive tract plays an important role in the body not only of humans, but also of animals. For example, animals also have microflora, the imbalance of which leads to diseases of the gastrointestinal tract.

Microbes are the most numerous representatives of our planet; they fill absolutely all the space available to them. In the process of evolution, microorganisms have adapted to exist in certain conditions, so-called econiches, and humans are one of them. Microorganisms have learned to coexist with humans, and not only to exist, but also to bring benefits - both to themselves and to their owner. Evolution has influenced the fact that certain types of microorganisms are able not only to live in the human intestine, but also to take care of his immune system, and also to be the main and irreplaceable link in the functioning of the digestive system.

Factors that contribute to overgrowth of intestinal flora:

• the presence of fistulas in the intestines;
• surgical operations;
• atrophic gastritis;
• the use of medications, especially antibiotics, which kill both pathogenic and beneficial microflora;
• impaired intestinal motility;
• intestinal obstruction and much more.

The microflora of the gastrointestinal tract is divided into luminal and parietal flora; their composition is different. The composition of the wall flora is more stable and is represented mainly by lactobacilli and bifidobacteria, which protect the intestines from pathogenic bacteria. The composition of the luminal flora, in addition to lacto- and bifidobacteria, includes a number of other intestinal inhabitants.

Normal human flora is a single and coordinated mechanism; it is a sensitive indicator of the state of the human body when exposed to various factors.

1. Protective. Normal flora suppresses pathogenic and foreign flora that enter our body with water and food. This is ensured by the following mechanisms:
   • Normal flora activates the synthesis of antibodies in the mucous membrane of the gastrointestinal tract, which have binding ability against foreign antigens;
   • Microflora produces substances that can suppress opportunistic and pathogenic flora;
   • Flora produces lactic acid, lysozyme, hydrogen peroxide and other substances with antibiotic activity;
2. Enzymatic. Normal flora digests carbohydrates and proteins, and also produces hemicellulase, which is responsible for the digestion of fiber. In turn, digested fiber, when interacting with normal flora, forms glucose and organic acids, which stimulate intestinal motility and form stool;
3. Synthesis of vitamins. It is mainly carried out in the cecum, since this is where they are absorbed. Microflora ensures the synthesis of B vitamins, nicotinic acid and other vitamins. For example, bifidobacteria provide the synthesis of vitamin K, pantothenic and folic acid;
4. Synthesis of proteins and amino acids. Especially in cases of their deficiency;
5. Exchange of microelements. Microflora helps to enhance absorption processes through the intestines of iron, calcium ions, vitamin D;
6. Neutralization or detoxification of xenobiotics (toxic substances). This function is an important process of the intestinal microflora, which occurs as a result of its biochemical activity;
7. Immune. Normal flora stimulates the formation of antibodies, and in children contributes to the formation and maturation of the immune system. Bifidobacteria regulate cellular and hormonal immunity, prevent the destruction of immunoglobulin, produce lysozyme and stimulate interferon formation. Lactobacilli increase the phagocytic activity of macrophages, neutrophils, the formation of interferons, the synthesis of immunoglobulins and interleukin-1.

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The versatility of normal microflora is an important component of maintaining its composition. The qualitative and quantitative composition of microflora is influenced by a large number of different factors: these are environmental conditions (sanitary and hygienic, professional, chemical, radiation and others), climatic and geographical conditions, quality and nature of nutrition, various immune disorders, physical inactivity, stress, and so on. ; The composition of the flora is also disrupted in various gastrointestinal diseases.

Helicobacter pylori is the cause of many gastrointestinal diseases

Helicobacter Pylori is a spiral-shaped bacterium that infects more than 30% of people worldwide. As a rule, the bacterium does not give clear symptoms, and therefore people with Helicobacter may not even be aware of its presence in their body. This bacterium is not so harmless and is the cause of a number of serious diseases of the gastrointestinal tract, including cancer.

How to recognize Helicobacter?

The most common symptoms: heartburn, bloating, constipation, diarrhea, reflux, flatulence, abdominal pain, belching.

As a rule, a person does not pay special attention to these symptoms and attributes them to the normal functioning of the body. Helicobacter is the main cause of inflammation of the stomach lining, commonly known as gastritis. Almost 80% of stomach ulcers and 90% of duodenal ulcers are caused by this bacterium.

However, Helicobacter not only manifests itself in gastrointestinal symptoms, but also with cardiovascular diseases, migraines, Raynaud's disease (poor circulation in the arms and legs).

The bacterium lives in the stomach lining of humans and animals. In people it can often manifest itself as frequent mood swings. Helicobacter is introduced into the body through consumption of contaminated water and food. Therefore, it is recommended to thoroughly rinse food, monitor the condition of water and wash your hands as often as possible, especially before eating.

The most popular and effective method of treating Helicobacter is antibacterial therapy, including antibiotics and medications that regulate stomach acidity. It is necessary to contact a gastroenterologist for diagnosis and prescribing the correct treatment.

Proper nutrition is equally important when treating this bacteria. It is necessary to include more vitamins A, C, E, and minerals, especially those containing zinc, which can protect the stomach lining. Probiotics such as lactobacilli and bifidobacteria can also be very effective in treating Helicobacter.

Bacteria of the gastrointestinal tract

Gastrointestinal diseases of piglets have a predominant distribution in infectious pathology and cause significant economic damage, being the main cause of death of animals. According to a number of authors, during bacteriological studies of samples obtained from sick and dead animals, in most cases microorganisms are represented by associations: Escherichia and Clostridia (31.7–35.2%); Escherichia, staphylococci and enterococci (33.4–35.1); Escherichia, enterococci and salmonella (32.4–33.6); salmonella and clostridia (10.4–11.2%).

Stress, as one of the causes, is associated with the occurrence of gastrointestinal and respiratory diseases in farm animals, in the development of which opportunistic and pathogenic microflora play a significant role. During the weaning period, piglets are exposed to two main stress factors - weaning from the sow and the transition from one type of feed to another. Often, recovered animals carry bacteria for a long period of time and become a constant source of environmental contamination.

Numerous technological stresses, caused by the intensive technology of growing and fattening pigs in production conditions, often exceed the compensatory capabilities of the pigs’ body in their intensity and lead to a decrease in immunological reactivity and disruption of the biocenosis of the gastrointestinal tract.

Antimicrobial agents widely used in practice are often ineffective and environmentally unsafe due to the formation of antibiotic-resistant strains of bacteria and a decrease in product quality.

Recently, preparations have been developed containing various organic acids that have an antibacterial effect, and substances to enrich diets with missing nutritional elements.

Purpose of the study– to study the effect of feed additives (Biofit, Bi Tan Dry Max, Lumantse) on the enterobiocenosis of piglets with a diarrheal symptom complex.

Objects and methods of research

The experiment was carried out at a pig-breeding complex in the Omsk region. Microbiological analysis was carried out in the bacteriological department of the industrial veterinary laboratory of the complex and on the basis of the Omsk Regional Veterinary Laboratory.

A total of 480 Landrace and Large White piglets took part in the experiment. The piglets were raised (37–60 days) in a pig farm with industrial housing and feeding technology.

To conduct the experiment, four groups of animals of 120 animals each were formed. Animals of the first experimental group received the Biofit feed additive containing lauric acid, mono- and diglycerides of fatty acids. Animals of the second group were included in the diet with the supplement Bi Tan Dry Max, containing salts of organic acids and yeast extract. The animals of the third group were given a drug containing a number of organic acids, essential oils, plant extracts, resins and yeast in their diet as a natural antibiotic.

The fourth group of animals served as control and received a normal diet.

Biological drugs were used daily in doses consistent with the manufacturers' recommendations.

During the experiment, the animals were clinically examined daily and feed intake was noted. Bacteriological studies of fecal samples were carried out before the use of additives and every fifth day until the end of the experiment (21 days).

The study of the intestinal microbiota of piglets was carried out according to the guidelines for the bacteriological diagnosis of colibacillosis (escherichiosis) in animals (Ministry of Agriculture and Food of the Russian Federation dated July 27, 2000 No. 13-7-2/2117); methodological guidelines for the accelerated indication of Morganella, Salmonella and enteropathogenic Escherichia with adhesive antigens in pathological material, feed, environmental objects in the coagglutination reaction (Ministry of Agriculture and Food of the Russian Federation dated October 11, 1999 No. 13-7-2/1758); methodological guidelines for the use of unified microbiological (bacteriological) research methods in clinical diagnostic laboratories (Appendix No. 1 to the order of the USSR Ministry of Health dated April 22, 1985 No. 535).

Research results

During the experiment, piglets in the experimental groups were in a satisfactory condition; when fed with feed additives, a reaction to the specific smell of the drugs was noted. In experimental group No. 1, where the Biofit feed additive was introduced into the diet, piglets periodically showed gastrointestinal upset (19.5%), and in the second group, where the Bi Tan Dry Max feed additive was used, animals were often observed sneezing when eating food, but the appetite was good. Diarrheal symptom complex in the second group was recorded in 16.1% of piglets. In experimental group No. 3, where the feed additive Lumantse was introduced into the diet, gastrointestinal disorder manifested itself in 17.8% of piglets. During the experiment, the diarrheal symptom complex in animals in the experimental groups was short-lived; deaths in the experimental groups were not recorded. In animals of the control group, appetite was reduced, in comparison with animals of the experimental groups, piglets more often registered a diarrheal symptom complex (32.2%).

When conducting bacteriological studies of fecal samples from animals in experimental groups with a diarrheal symptom complex, microorganisms of the Enterobacteriacae family were isolated; Staphylococcus, Enterococcus, Lactobacillus and Bifidobacterium.

In experimental group No. 1 (Biofit), E. coli (35.7%), Staphylococcus spp. cultures prevailed in the samples. (25.4), Citrobacter spp. (17.3), Enterobacter spp. (15.3%), Enterococcus faecalis (3.6) and Enterococcus faecium (2.1%).

In experimental group No. 2 (Bi Tan Dry Max), in most cases the following cultures were isolated: E. coli (53.4%), Citrobacter spp. (19.4), less often – Enterobacter spp. (13.7%), Enterococcus faecalis (7.4) and Enterococcus faecium (6.1%).

In experimental group No. 3 (Lyumanets), the following cultures were isolated: E. coli (43.6%), Staphylococcus spp. (27.3), Citrobacter spp. (18.2), Enterobacter spp. (6.5%), Enterococcus faecalis (2.6) and Enterococcus faecium (1.2%).

In the control group, during bacteriological examination of fecal samples from sick piglets, microorganisms of the Enterobacteriacae family were isolated; genera Staphylococcus, Enterococcus and Pseudomonas, namely: E. coli (38.4%), Staphylococcus spp. (18.3), Proteus vulgaris (18.6), Klebsiella spp. (1,3), Citrobacter spp. (4,2), Enterobacter spp. (5.4%), Yersinia enterocolitica (1.3%), Enterococcus faecalis (5.6%), Enterococcus faecium (5.1), Pseudomonas aeruginosa (1.3%).

Over the next two weeks, the animals in the experimental groups maintained good appetite and activity. Diarrheal symptom complex was not recorded. At the same time, in the experimental groups there were animals with a reduced live weight of 31.7% (group No. 1); 22.5 (group No. 2); 27.4% (No. 3).

In the control group, piglets showed decreased appetite, heterogeneity in weight, and a significant part of the animals were emaciated (27.1%).

At the end of the experiment, microbiological studies of fecal samples obtained from animals in the experimental and control groups were carried out. The results of the study are presented in the table.

As a result, a decrease in the number of staphylococci in the first group (Biofit) was established by 16.7%, in the second – by 58.3 (Bi Tan Dry Max), in the third (Lyumanets) – by 41.7%.

The number of enterococci in piglets in the first group (Biofit) decreased by 7.5%, in the second (Bi Tan Dry Max) - by 12.5, and in the third (Lyumanets) - by 12.8% compared to the control group. A slight increase in the number of lactobacilli in the first group by 3% was established, while in the second and third their number increased by 20%, which is very important, since these bacteria inhibit the growth and development of staphylococci, Escherichia, and salmonella due to the production of lactic acid. The number of actino- and micromycetes in all groups was insignificant both at the beginning of the experiment and after completion.

The content of bifidobacteria in piglets in experimental group No. 1 (Biofit) was 109–1010 CFU, in group No. 2 (Bi Tan Dry) and No. 3 (Lumantse) – 1010, while in the control group this figure was 107–108 CFU. The greatest proliferation of bifidobacteria was facilitated by feed additives No. 2 and 3 (Bi Tan Dry Max, Lumantse). Bifidobacteria are involved in parietal digestion, have pronounced adhesion to the cells of the intestinal mucosa, prevent the proliferation of pathogenic microorganisms due to the formation of biofilm, as a result, the number of staphylococci and enterococci is reduced.

After conducting bacteriological studies with cultures classified by morphological, cultural and enzymatic properties as belonging to the genus Escherichia, reactions were carried out with agglutinating adhesive sera. In the control group, animals were found to have a pathogenic culture of E. coli strain F41. In a serological reaction with O-coliagglutinating sera, pathogenic strains of enterohemorrhagic E. coli were detected: O157: H7 and O115.

When conducting comprehensive studies, it was established that the feed additives Bi Tan Dry Max, Lumantse and Biofit have a positive effect on the composition of the microbiota of the gastrointestinal tract, effectively controlling the balance of microorganisms in relation to pathogenic and opportunistic bacteria. It has been established that the feed additives Bi Tan Dry Max and Lumantse most actively influence the reproduction and growth of bifidobacteria and lactobacilli, promoting better digestibility of the nutritional components of the feed.

FSBEI HE "Omsk State Agrarian University" named after. P. A. Stolypina (Institute of Veterinary Medicine and Biotechnology)

The microflora of the oral cavity is represented by numerous types of aerobic and anaerobic microorganisms, since there are quite favorable conditions for them here - the alkaline reaction of saliva, the presence of food residues, and a temperature favorable for reproduction (37 degrees). Immediately after the birth of a child, aerobic flora is formed in his oral cavity - cocci, rods; With teething, anaerobic bacteria appear, including vibrios, spirilla, spirochetes, and clostridia.

In the oral cavity there is continuous contamination by microbes and self-cleaning under the influence of lysozyme, inhibin and other factors, as a result of which a more or less constant microflora is formed, the most common representatives of which are staphylococci, streptococci, Candida fungi, lactobacilli, neisseria, spirochetes, vibrios, anaerobes are constantly present - veillonella, bacteroides, peptostreptococci. Sometimes protozoa, aspergillus, yeast and other microorganisms are isolated from the saliva of healthy people. The esophagus in healthy people is usually free of microorganisms or very little populated by them.

Stomach. Due to the acidic reaction of the environment, unfavorable for the development of microorganisms, specific microflora took root in the stomach: yeast, sarcina, fungi, lactobacilli, staphylococci, streptococci, campylobacters, etc., but not putrefactive bacteria (up to 30 species in total). A change in the composition of the microflora, in particular the appearance of putrefactive bacteria, is a sign of disruption of the normal function of gastric secretion.

Small intestine. The microflora is not abundant and rather monotonous: lactobacilli, enterococci, bifidumbacteria, E. coli and some others. The proliferation of bacteria is prevented by the bacteriostatic effect of bile, secretions of the mucous membrane and secretory immunoglobulins of the IgAs class. In some cases, for example due to impaired gastric secretion or damage to the intestinal mucosa as a result of radiation exposure, or due to diseases of the liver, biliary tract and pancreas, or immunodeficiency, people develop small intestinal overcolonization syndrome. It lies in the fact that in the small intestine the concentration of a bacterial population, similar in species and quantitative composition to the microflora of the large intestine, increases sharply. Such accumulation of unusual microflora in the small intestine can lead to various disorders of its function and to the phenomena of enteral insufficiency.

The microflora of the large intestine is the most abundant and diverse. The peculiarities of the living conditions for microorganisms in the large intestine are that it is not a secretory organ, but an excretory one, it lacks lysozyme, the lymphoid tissue is represented less powerfully, at the same time, there are favorable pH, temperature, abundance of nutrients, etc.

The formation of the microflora of the large intestine begins with the child’s first breath, but in the first three days, while the child is fed colostrum (milk enriched with the mother’s immunoglobulins), various bacteria, including putrefactive ones, multiply in the large intestine. As soon as he begins to feed on his mother's breast milk, putrefactive bacteria disappear and a permanent microflora is formed, in which bacteria predominate, forming lactic acid during the fermentation of glucose. More than 260 species of bacteria have been found in the large intestine, their total biomass is about 1.5 kg.

The microflora of the large intestine can be divided into the following four groups:

The bulk of the microflora consists of strict anaerobes that do not form spores: gram-positive bacteria of the genus Bifidobacterium and gram-negative bacteria of the family Bacteroidaceae. Bifidobacteria and bacteroides account for up to 96-99% of the total microflora of the large intestine.

The second group consists of facultative anaerobes, represented mainly by gram-negative E. coli and gram-positive enterococci and lactic acid bacilli of the genus Lactobacillus (they do not form spores). They account for 1-4% of the total microflora.

The third group is the so-called residual microflora, which accounts for 0.001-0.01% of all microorganisms of the large intestine. This group includes: Staphylococcus, Proteus, Candida, Clostridium, Pseudomonas.

The fourth group includes various other members of the family Enterobacteriaceae, which can be temporarily or permanently found in the intestines and cause intestinal infections (Salmonella, Shigella, Enterobacter and other genera).

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Normal human microflora is a collection of many microbiocenoses, characterized by certain relationships and habitat.

In the human body, in accordance with living conditions, biotopes with certain microbiocenoses are formed. Any microbiocenosis is a community of microorganisms that exists as a single whole, connected by food chains and microecology.

Types of normal microflora:

1) resident – ​​permanent, characteristic of a given species;

2) transient - temporarily introduced, uncharacteristic for a given biotope; it does not actively reproduce.

Normal microflora is formed from birth. Its formation is influenced by the microflora of the mother and the hospital environment, and the nature of feeding.

Factors influencing the state of normal microflora.

1. Endogenous:

1) secretory function of the body;

2) hormonal levels;

3) acid-base state.

2. Exogenous living conditions (climatic, household, environmental).

Microbial contamination is typical for all systems that have contact with the environment. In the human body, blood, cerebrospinal fluid, joint fluid, pleural fluid, thoracic duct lymph, internal organs: heart, brain, parenchyma of the liver, kidneys, spleen, uterus, bladder, lung alveoli are sterile.

Normal microflora lines the mucous membranes in the form of a biofilm. This polysaccharide framework consists of polysaccharides from microbial cells and mucin. It contains microcolonies of normal microflora cells. Biofilm thickness is 0.1–0.5 mm. It contains from several hundred to several thousand microcolonies.

The formation of a biofilm for bacteria provides additional protection. Inside a biofilm, bacteria are more resistant to chemical and physical factors.

Stages of formation of normal microflora of the gastrointestinal tract (GIT):

1) accidental contamination of the mucous membrane. Lactobacilli, clostridia, bifidobacteria, micrococci, staphylococci, enterococci, E. coli, etc. enter the gastrointestinal tract;

2) formation of a network of tape bacteria on the surface of the villi. Mostly rod-shaped bacteria are fixed on it, and the process of biofilm formation is constantly underway.

Normal microflora is considered as an independent extracorporeal organ with a specific anatomical structure and functions.

Functions of normal microflora:

1) participation in all types of exchange;

2) detoxification in relation to exo- and endoproducts, transformation and release of medicinal substances;

3) participation in the synthesis of vitamins (groups B, E, H, K);

4) protection:

a) antagonistic (associated with the production of bacteriocins);

b) colonization resistance of mucous membranes;

5) immunogenic function.

The highest contamination rates are characterized by:

1) large intestine;

2) oral cavity;

3) urinary system;

4) upper respiratory tract;

2. Dysbacteriosis

Dysbacteriosis (dysbiosis) is any quantitative or qualitative changes in the normal human microflora typical for a given biotope, resulting from the impact of various unfavorable factors on a macro- or microorganism.

Microbiological indicators of dysbiosis are:

1) reduction in the number of one or more permanent species;

2) loss of certain characteristics by bacteria or acquisition of new ones;

3) increase in the number of transient species;

4) the appearance of new species unusual for this biotope;

5) weakening of the antagonistic activity of normal microflora.

The causes of dysbacteriosis may be:

1) antibiotic and chemotherapy;

2) severe infections;

3) severe somatic diseases;

4) hormone therapy;

5) radiation exposure;

6) toxic factors;

7) vitamin deficiency.

Dysbacteriosis of different biotopes has different clinical manifestations. Intestinal dysbiosis can manifest itself in the form of diarrhea, nonspecific colitis, duodenitis, gastroenteritis, and chronic constipation. Dysbacteriosis of the respiratory system occurs in the form of bronchitis, bronchiolitis, and chronic lung diseases. The main manifestations of oral dysbiosis are gingivitis, stomatitis, and caries. Dysbacteriosis of the reproductive system in women occurs as vaginosis.

Depending on the severity of these manifestations, several phases of dysbacteriosis are distinguished:

1) compensated, when dysbiosis is not accompanied by any clinical manifestations;

2) subcompensated, when local inflammatory changes occur as a result of an imbalance of normal microflora;

3) decompensated, in which the process generalizes with the appearance of metastatic inflammatory foci.

Laboratory diagnosis of dysbiosis

The main method is bacteriological examination. At the same time, quantitative indicators prevail in assessing its results. Species identification is not carried out, but only to the genus.

An additional method is chromatography of the spectrum of fatty acids in the material under study. Each genus has its own spectrum of fatty acids.

Correction of dysbiosis:

1) eliminating the cause that caused the imbalance of normal microflora;

2) the use of eubiotics and probiotics.

Eubiotics are preparations containing live bacterinogenic strains of normal microflora (colibacterin, bifidumbacterin, bificol, etc.).

Probiotics are substances of non-microbial origin and food products containing additives that stimulate one’s own normal microflora. Stimulating substances - oligosaccharides, casein hydrolysate, mucin, whey, lactoferin, dietary fiber.