Bacteria in the digestive tract can contribute to and be affected by diseases in a variety of ways. The main site of attack is the lower ileum, where salmonella causes mucous ulcers. They quickly make their way through the epithelial surface into the lamina propria and enter the lymphatic vessels and bloodstream. At least two virulence factors are associated with intestinal infection: one is responsible for the invasion of mucous membranes, and the other causes the secretion of fluid and electrolytes in the intestine. Our intestinal flora plays an important role in providing vitamins and other nutrients essential to our health. The microbiome also interacts with carbohydrates that have not been digested in the small intestine (such as resistant starch and FODMAPs). This interaction provides other nutrients, promotes the growth of epithelial cells and modulates fat storage. For asthma, two hypotheses have been put forward to explain its increasing prevalence in developed countries. The hygiene hypothesis postulates that children in developed countries are not exposed to enough microbes and may therefore contain a lower prevalence of specific bacterial taxa that play a protective role. [123] The second hypothesis focuses on the Western model diet, which lacks whole grains and fiber, and has an abundance of simple sugars.

[13] The two hypotheses converge via the role of short-chain fatty acids (SCFAs) in immunomodulation. These bacterial fermentation metabolites are involved in immune signaling that prevents asthma from triggering, and lower levels of SCFAs are associated with the disease. [123] [124] Missing protective genera such as Lachnospira, Veillonella, Rothia and Faecalibacterium have been associated with reduced levels of SCFAs. [123] In addition, SCFAs are the product of bacterial fibre fermentation, which is low in the Western model diet. [13] [124] SCFAs link gut flora to immune diseases and has been an active area of research since 2016. [13] Similar hypotheses have been put forward for the increase in food and other allergies. [125] Several enterotoxin-producing bacteria cause diarrhea (Table 95-1). Diarrhoea caused by Vibrio cholerae and enteroxogenic strains of E. coli.

coli has three main characteristics. First, there is the loss of intestinal fluid, which is related to the effect of an enterotoxin on the epithelial cells of the small intestine. Secondly, the organism itself does not penetrate into the mucous surface; On the contrary, it colonizes the upper small intestine, adheres to epithelial cells and works enterotoxin. The mucosal architecture remains intact and shows no signs of cell destruction. Bacteremia does not occur. Third, fecal wastewater is watery and often bulky, so diarrhea can lead to clinical dehydration. The fluid comes from the upper small intestine. where enterotoxin is most active. The gut microbiota is made up of microorganisms, including bacteria and archaea, that live in the digestive tract of vertebrates, including humans and insects. [1] [2] Alternative terms include gut flora (an obsolete term that technically refers to plants) and gut microbiome.

The gastrointestinal metagenome (sometimes called the microbiome) is the totality of all genomes in the gut microbiota. [3] [4] In humans, the gut is the main site of the human microbiota. [5] The gut microbiota has far-reaching effects, including colonization, pathogen resistance, maintenance of the intestinal epithelium, metabolism of food and pharmaceutical compounds, control of immune function, and even gut-brain axis behavior. Concentration of bacterial flora in the regions of the gastrointestinal tract. The diversity of gut flora appears to be significantly reduced in people with inflammatory bowel disease compared to healthy people; In addition, proteobacteria and actinobacteria seem to dominate in people with ulcerative colitis; in people with Crohn`s disease, Enterococcus faecium and several proteobacteria appear to be overrepresented. [4] The gut flora is able to ferment indigestible carbohydrates (fiber) into short-chain fatty acids such as acetate, propionate and butyrate. The main source of these fermentable carbohydrates in the human colon are plant cell wall polysaccharides such as pectins, cellulose and hemicellulose. The acids produced by bacteria from these fiber substrates can be an important source of energy for the host. The intestinal flora can prevent infection by interfering with pathogens. The flora includes small populations of potentially pathogenic organisms such as Clostridium difficile. Antibiotics that disrupt the balance of normal flora can promote both infection with exogenous pathogens and proliferation with endogenous pathogens.

If the intestinal wall is broken, intestinal bacteria can escape into the peritoneum and cause peritonitis and abscesses. The metabolic capacities of intestinal bacteria are extremely diverse. Bacterial enzymes can use virtually any compound in the intestinal lumen as a substrate, whether taken orally or entering the intestine by secretion through the bile ducts or directly through the mucosa. Just as gut flora can function in a feedback loop that can lead to the development of obesity, there is evidence that restricting calorie intake (i.e. dieting) can lead to changes in gut flora composition. [121] As mentioned earlier, your gut flora plays a key role in your health. Two of the most important roles have to do with protecting the immune system and metabolism. For these important functions, an optimal preponderance of “friendly” bacteria must be present. Let`s look at each of these functions in order: antibiotics block enterohepatic circulation, suppressing the intestinal microflora, thereby reducing the content of deconjugating enzymes. When an antibiotic is given to a patient who is also taking a drug subject to enterohepatic circulation, the resulting depression of the enterohepatic circulation increases the fecal excretion of the drug, thereby lowering its plasma levels and half-life. For example, blood levels and half-life of estrogen in birth control pills decrease when antibiotics are administered.

The microbial composition of the gut microbiota varies in the digestive tract. In general, relatively few types of bacteria are present in the stomach and small intestine. [6] [15] The colon, on the other hand, contains the highest microbial density recorded in Earth`s habitat[16] with up to 1012 cells per gram of intestinal contents. [6] These bacteria represent between 300 and 1000 different species. [6] [15] However, 99% of bacteria come from about 30 or 40 species. [7] Due to their abundance in the gut, bacteria also make up up to 60% of the dry matter of feces. [8] Fungi, protists, archaea and viruses are also present in the intestinal flora, but less is known about their activities. [17] Invasive diarrhea: Invasive bacteria such as Shigella and Campylobacter invade the intestinal mucosa. A bloody chair against mucous diarrhea with inflammatory exudate is produced. The same mechanisms that control normal flora also protect the intestine from the penetration of pathogens. Stomach acid in the stomach kills most of the organisms that are swallowed. People with reduced or absent stomach acid have a high incidence of bacterial colonization in the upper small intestine and are more susceptible to bacterial diarrhea.

Bile has antibacterial properties and can therefore be another factor in the control of flora. Forward motility (peristalsis) is a key element in suppressing the flora of the upper intestine. After all, the microflora itself, producing its own antibacterial substances (for example, bacteriocins and fatty acids), stabilizes the normal population and prevents the implantation of pathogens. Bacteria make up most of the colon flora[33] and 60% of the dry matter of feces. [6] This fact makes feces an ideal source of gut flora for testing and experimentation by extracting nucleic acid from stool samples, and bacterial 16S rRNA gene sequences are created using bacterial primers.