To the heap I pulled from the Internet what I agree with myself.
1016 microbial symbiont cells simultaneously interact with the human body.
Physiology of intestinal microflora
Under physiological conditions, the intestinal mucosa is covered with a biofilm, inside which there are exopolysaccharide matrix of microbial origin and mucin of the goblet cells of the mucous membrane.
Despite the fact that the thickness of this film is only from fractions to tens of microns, the number of microcolonies of normal flora in it can reach several hundreds or even thousands, and the resistance of bacteria to the effects of adverse factors inside this biofilm is tens and hundreds of times higher than in free cells.
Unlike luminal bacteria, representatives of mucosal microflora in the body are able to fix only to strictly defined receptors of the skin and mucous membranes.
The specific and anatomical specificity of adhesion of representatives of mucosal microflora is so pronounced that bacteroids from the oral mucosa cannot colonize the nasopharynx or intestines of the same animal for a long time.
The mucous flora is more stable and is represented mainly by bifidobacteria and lactobacilli, which form a layer of "bacterial turf". The latter prevents the penetration of the mucous membrane by pathogenic and opportunistic microorganisms.
The luminal flora, along with bifidobacteria and lactobacilli, includes other permanent inhabitants of the intestine.
The microflora of the esophagus and stomach in healthy people is not stable and constant, since it is closely related to the nature of the food taken.
The esophagus does not have a permanent microflora at all, and the bacteria present represent the microbial world of the oral cavity.
The microbial spectrum of the stomach is poor. It is mainly represented by: lactobacilli, streptococci, staphylococci, micrococci, Helicobacteria and acid-resistant yeast-like fungi, located in the thickness of gastric mucus.
The highly bactericidal gastric juice remains practically sterile, since the luminal microflora that enters the stomach as part of the food lump dies within 30 minutes.
As the contents move inside the intestinal tube, the partial pressure of oxygen decreases and the pH of the medium rises; therefore, each subsequent biotype of the digestive system has a significant increase in the number of facultative and obligate anaerobic bacteria with a simultaneous decrease in the number of aerobic bacteria.
The microflora of the small intestine is quite simple and not numerous. It is dominated by streptococci and lactobacilli. The microorganisms inhabiting here are localized mainly parietally.
The composition of the microflora of the distal ileum differs significantly from the biotopes described above. Firstly, the total number of bacteria increases - 106 microbial cells per 1 g, secondly, the intraluminal microflora prevails over the parietal microflora, and thirdly, an important ecological feature of this biotope is the approximately equal number of aerobic and anaerobic bacteria (enterococci, Escherichia coli, bacteroids , veyonella, bifidobacteria).
The large intestine is a biotope with a high degree of microbial contamination (more than four hundred types of microorganisms). These are mainly obligate anaerobic bacilli (bifidobacteria and bacteroids), which account for 90% of all microorganisms.
The remaining 10% are aerobic and facultative anaerobic bacteria: E. coli, lactobacilli, enterobacteria, streptococci and spore-bearing anaerobes.
The density of bacteria, according to Alana Parkera (1999), in various parts of the gastrointestinal tract is:
stomach - less than 1000 per ml;
jejunum - less than 10,000 per ml;
ileum - less than 100,000 per ml;
colon - less than 1 trillion per ml.
The composition of the intestinal microflora changes during a person's life.
It is no coincidence that mammals and humans are arranged in such a way that at the moment of birth, the newborn is automatically seeded with the natural microflora of the mother's body, i.e., significant colonization of the fetus by microbes begins already during childbirth, thereby ending its sterile intrauterine existence.
During physiological childbirth, the source of primary colonization (by microorganisms) of the fetus is microorganisms related to the child's body from the microflora of the vagina, as well as the intestines and skin of the mother.
From this point of view, excessive concern about the "sterility" of conditions for the newborn during childbirth may be the first step towards dysbiosis. The era of antibiotics, under the conditions of their uncontrolled use, has also made a significant contribution to the increase in the number of dysbiosis. Further developing the ideas of microbiological endoecology, it can be assumed that the birth of a child by cesarean section also gives a certain amount of dysbiosis.
Our healthcare workers are surprised at how widespread access is for a husband and relatives to a newborn and mother in US maternity hospitals. What is most surprising is the absence of negative consequences for the child in terms of infection. In Russia, against the background of an almost complete ban on any contacts, maternity hospitals "bloom".
What is the reason? Apparently, one of the reasons is that a newborn, deprived of the microflora of the mother and family useful and protective for him, is seeded by the microflora of medical personnel alien to his body, i.e.the second source of microorganisms is the hospital environment, which to a greater extent affects the formation of microbiocenoses in the newborn's body due to the immaturity and imperfection of its immune system.
It has been proven that during the first five days of a child's life, the strains of microorganisms obtained from the mother during childbirth are displaced, and the intestines are intensively colonized by hospital strains of opportunistic microorganisms.
The most significant risk factors for the development of intestinal dysbiosis in young children are their late attachment to the mother's breast, transfer to mixed and artificial feeding.
Such children more often than those receiving breast milk suffer from intestinal diseases.
In other words, in a child's life, two of the most critical moments can be distinguished that have an exceptional effect on the bacterial colonization of the intestine. The first is when the baby is born and the second is when the baby is weaned. In connection with a significant qualitative change in the nature of nutrition, pronounced qualitative and quantitative changes in the composition of the intestinal microflora occur in a fairly short time.
The main functions of normal intestinal microflora are:
- ensuring the colonization resistance of the organism (i.e., inhibiting the growth and reproduction of pathogenic and opportunistic microbes in it);
- participation in the synthetic, digestive and detoxifying functions of the intestine;
- stimulation of the synthesis of biologically active substances (a-alanine, 5-aminovaleric and g-aminobutyric acids, as well as mediators that affect the function of the gastrointestinal tract, liver, cardiovascular system, hematopoiesis, etc.);
- maintaining high levels of lysozyme, secretory immunoglobulins, interferon, cytokines, properdin and complement, important for immunological resistance;
- morphokinetic effect and increased physiological activity of the gastrointestinal tract.
Research has shown that most of us don't even get the RDA of 10 vitamins and minerals. In real life, less than 10% of the population in developed countries consumes the recommended amount of fruits, 40% do not eat fruits and vegetables at all.
In addition, many of these vegetables and fruits are gradually losing their beneficial properties due to artificial growing conditions, soil depletion, the use of chemical fertilizers, long-term storage before going on sale, etc.
The development of a new direction in human nutrition - the so-called functional nutrition - is of great interest. The products of this group are isolated from natural sources, have certain regulatory functions, and soon they will be able to compete with many drugs on the market.
The main categories of functional nutrition are: dietary fiber, eicosapentanoic acid, foods containing bifidobacteria and oligosaccharides. A significant place in the world market is occupied by food products containing bifidogenic factors that stimulate the growth and development of bifidobacteria (lactulose, soy oligosaccharide, xylobiose, etc.).
Correction of intestinal dysbiosis
Correction of intestinal dysbiosis is determined by the nature of the microbial landscape, the age factor, the nature of feeding and food tolerance, and is built in three directions: suppression of the growth of one conditionally pathogenic microorganism, colonization of the intestine with normal symbiotes using probiotics and selective stimulation.
In the correction of intestinal dysbiosis, the most studied and, to a certain extent, practically implemented direction is the use of biological bacterial preparations based on microorganisms - representatives of normal human microflora, the so-called probiotics.