Normal microflora of humans and animals. Microflora of the animal body
ESSAY
Topic: "Interaction of microorganisms with humans and animals"
by discipline: "General biology and microbiology"
Student
gr. X-350007 Lezhneva M.D.
Teacher
Associate Professor, Ph.D. Berseneva V.S.
Ekaterinburg
1. Normal microflora of humans and animals. 3
1.1. Normal microflora gastrointestinal tract person. 6
1.2. Normal microflora of the gastrointestinal tract of animals. 7
1.3. Skin microflora. 8
1.4. The microflora of the respiratory organs. 8
1.5. Microflora of the genitourinary system.. 8
2. Pathogenic microorganisms.. 9
3. The role of normal microflora in the formation of eubiosis. eleven
Conclusion. 12
References.. 13
Introduction
According to modern ideas, in natural environment habitat requires a symbiosis of the macroorganism with the microflora inhabiting it. It is generally accepted that in the process of evolution, during the interaction of the host organism and microorganisms, certain types of them were selected, capable of attaching and colonizing the surface epithelium of the mucous membranes of the corresponding ecological niches. As a result, they began to use the host organism as a new habitat. Thus, symbiotic associations were formed that make up the normal microflora of humans and animals.
Microbial-free animals (and plants) can only live and develop in conditions of artificial isolation (sterile environment).
Representatives of the normal microflora are studied in detail already at the genetic and molecular levels. The composition of the normal microflora of not only various organs is known respiratory tract, gastrointestinal tract, genitourinary system, skin surface, but also the hierarchical-topographic distribution of certain types of microbes along the alimentary canal, reproductive tract in women, etc.
The macroorganism and the microflora inhabiting it, including the intestines, are a balanced ecological system. The presence of permanent (indigenous) and transient (random) microflora was shown.
The normal microflora of animals and humans constantly persists in the body of a healthy host and interacts with it according to the principle of symbiosis.
A living organism contains a huge number of symbiont microorganism cells (up to 1014). Their species diversity (over 400 species) ensures the participation of normal microflora in a wide variety of physiological functions of the macroorganism.
Normal microflora of humans and animals
From the moment of their birth, humans and animals enter the microbial environment that accompanies them everywhere. life path. Microbes settle not only on the surface of the body of a macroorganism, but also penetrate inside, populating various organs and tissues.
Certain relationships are established between micro- and macroorganisms, the nature of which is determined by the biological nature of the organisms and the conditions for their development.
The microflora that constantly lives in the human and animal body and does not cause violations of its physiological functions is called normal.
Normal microflora should be considered in unity with the whole organism. It was formed in the process of evolution of animals and humans as a symbiotic microflora.
Normal microflora is represented mainly by bacteria. They live on the surface of the skin, in the oral cavity, in the gastrointestinal tract and respiratory tract. Depending on the habitat, the quantitative ratios of individual species vary, although each area of the body has its own stable microflora.
The surface of the skin contains mainly coccal forms: staphylococci, streptococci, sarcins. But along with them, there can be rod-shaped bacteria and yeast fungi. The source of nutrition for them is the secretions of sweat and sebaceous glands. Therefore, contaminated skin more contaminated with microorganisms.
The microflora of the oral cavity is more abundant and diverse. These are streptococci different types, lactobacilli, veillonella, yeast-like fungi of the genus Candida and corynebacteria are quite often found.
From the oral cavity through the esophagus, microorganisms enter the stomach. But the microflora of the stomach is poorer, since the acidic reaction of the gastric juice does not favor the development of most of the microbes that have entered it. In the stomach, species that tolerate an acidic environment are mainly developed - lactic acid streptococci, enterococci, sarcins, yeast. There are also other microbes - spore-bearing rods, aerobacter, Escherichia coli, actinomycetes.
The microflora of the rumen (prestomach) of ruminants is very diverse and numerous. The number of microorganisms in 1 g of the contents of the rumen reaches 20 billion, while in the stomach they number only a few tens of thousands. Cellulose-destroying bacteria make up a significant amount of the rumen microflora. They play an important role in the assimilation of vegetable food by ruminants (cows, goats, sheep), which do not form the cellulose enzyme necessary for the hydrolysis of fiber. Therefore, the initial biochemical transformation of cellulose and the assimilation of the resulting products by animals are carried out exclusively due to the presence of cellulose-destroying bacteria in the rumen. The relationship of the rumen microflora with animal organisms is of the symbiotic type.
In the small intestine of humans and animals, the content of microorganisms is negligible, although the reaction of the environment there is alkaline. It is assumed that the mucous membrane of the small intestine has bactericidal properties. The main inhabitants of this cavity are enterococci, Escherichia and acidophilus coli, yeast.
The region of the large intestine is richest in microflora. It includes about 240 species of microbes, among which, according to L. G. Peretz (1962), enterococcus is 49%, and Escherichia coli 42.4%. These are mandatory representatives of the normal microflora of the large intestine. Most of them are commensals, in connection with which their relationship with microorganisms is called commensalism (a kind of symbiosis). This is a type of relationship when one of the symbionts receives nutrients or any other benefits at the expense of the other, without causing him any harm.
Normal microflora plays a positive role in the body, due to its antagonistic, enzymatic and vitamin-forming functions. This has been proven on animals experimentally grown in special chambers, free from microorganisms. Such “sterile” or “microbial-free” animals from birth and throughout their lives are called gnotobionts (from Greek gnoto - known, bios - life), or axenic animals (from Greek a - without, kseno - outsider).
An essential feature of such animals is their increased sensitivity to the action of microorganisms. Infecting them with microorganisms that are completely harmless to ordinary animals often leads to lethal outcome. Thus, the protective function of the normal microflora of the microorganism was established. For example, under normal conditions, animals are insensitive to the causative agent of cholera, it is dangerous only for humans. However, if guinea pigs raised under sterile conditions are infected with this microorganism, they become ill with cholera and die after 6-9 days. This means that the absence of normal microflora in the intestines of guinea pigs favors the development of the pathogen, while under natural conditions this microflora has an antagonistic effect on Vibrio cholerae. Escherichia coli has antagonistic properties against pathogens of dysentery, paratyphoid, staphylococci and streptococci, as well as various putrefactive bacteria. Coccal forms of the nasal cavity and tonsils inhibit the development of diphtheria and ozena bacteria.
The intestinal microflora plays an important role in providing the microorganism with vitamins. It is believed that the intestinal microflora provides the needs of animals for biotin and folic acid. It also synthesizes vitamins C and K.
In general, normal microflora plays a positive role. However, under certain conditions, some of its representatives can become pathogens. For example, Escherichia coli often turns out to be the causative agent of peritonitis, appendicitis, gallbladder diseases; viridescent streptococcus causes endocarditis and other diseases; streptococci living on the skin often cause furunculosis. All these diseases are called autoinfection. They are based on changes in the macroorganism - damage to organs and tissues, reduced immunity, as well as genetic and phenotypic changes in representatives of the normal microflora. So, when exposed to a macroorganism and other uncontrolled conditions, virulent strains can form from ordinary strains. Therefore, certain types of normal microflora - E. coli, staphylococci, streptococci, enterococci - are called conditionally pathogenic.
In some cases, there may be a violation in the composition of the normal microflora, leading to a change in the ratio between individual species. This phenomenon is called dysbacteriosis. The development of dysbacteriosis can be a consequence of the use of antibiotics, chemotherapy drugs, a decrease in immunity as a result of various reasons.
The occurrence of dysbacteriosis is associated with the suppression of the development of antagonist microbes that regulate the composition of normal microflora. As a result, pathogenic and conditionally pathogenic microorganisms actively multiply. The number of bacteria of the genera Pseudomonas, Proteus, which are the cause of nosocomial infections, fungi of the genus Candida, causing candidiasis, is sharply increasing. The consequence of dysbacteriosis is a significant increase in antibiotic-resistant strains of bacteria, a violation of vitamin-forming and enzymatic functions of normal microflora, and a weakening of the body's immune resistance.
Treatment of dysbiosis is aimed at restoring the normal composition of the microflora of the body. For this purpose, preparations containing suspensions of living microorganisms - representatives of the normal human microflora - are used.
Such drugs are lactobacterin, made on the basis of live cultures of lactic acid bacteria, colibacterin, containing a live culture of Escherichia coli (strain M-17), bifikol - an associated drug from bifidobacteria and Escherichia coli, and others. The use of these drugs is designed to ensure that the introduced microorganisms, due to their antagonistic properties, will displace pathogenic bacteria and provide conditions for the development and restoration of normal microflora.
Thus, the human microflora is a collection of microorganisms that live on the skin and mucous membranes. In fact, it is a metabolic system that synthesizes and destroys its own and foreign substances involved in the adsorption and transfer of both useful and, alas, potentially harmful substances into the human body.
The normal state of microflora (eubiosis) is a qualitative and quantitative ratio of various microbes of individual organs and systems that maintains the biochemical, metabolic and immune balance of the microorganism necessary to maintain human health. The most important function 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.
After birth, the animal body comes into contact with various microorganisms that penetrate through the respiratory and digestive tract and colonize the gastrointestinal tract, genital and other organs. The permanent inhabitants of the body of animals are microorganisms, some of which constitute the obligate microflora, others are in the body temporarily, getting from the soil, air, water and feed.
Skin microflora. Permanent inhabitants of the skin - staphylococci, streptococci, sarcins, actinomycetes, micrococci, causing suppurative processes: boils, abscesses, phlegmon, etc.
From rod-shaped forms, intestinal, pseudomonas, pseudodiphtheria are found. Microbes from the group of aerobes and anaerobes also get on the skin. The number of microbes on the skin depends on the conditions in which animals are kept: with poor care, up to 1-2 billion microbial bodies can be found per 1 cm of the skin surface.
Udder microflora. The microflora of the udder consists mainly of micrococci (M. luteus, M. flavus, M. candidus, M. caseolyticus), staphylococci, streptococci, corynebacteria, in particular Corynebacterium bovis. Due to the presence of coarse and small folds, the outer skin of the udder is a place of accumulation of almost all microbes that live in livestock buildings, on pastures, in bedding, feed, on the hands of a milkmaid and other environmental objects. With insufficient cleaning and disinfection of the premises, more than 10 microbes per 1 cm of udder skin are usually found, as a result of which the udder can become one of the main sources of contamination of milked milk.
Of the pathogenic microbes on the skin of the udder, mastitis pathogens (Str. agalactiae, Str. uberis, Staph. aurcus) and colimastitis (Escherichia coli, Klebsiella aerogenes, Corynebacterium pyogencs, Vas. subtilis, Pseudomonas aerugynosa, etc.) are often found. Str. is of particular importance. agalactiae, which causes 70-80% of all bacterial mastitis.
Microflora of the conjunctiva. A relatively small number of microbes are found on the conjunctiva. As a rule, these are staphylococci, streptococci, sardines, mycoplasmas, micrococci, actinomycetes, yeasts and molds are less common.
The microflora of the respiratory tract. In newborn animals, there are no microorganisms in the respiratory tract. When breathing on the mucous membranes of the upper respiratory tract, various bacteria, actinomycetes, molds and yeasts, mycoplasmas, etc. settle from the air. The permanent inhabitants of the mucous membranes of the nasopharynx and throat are mainly coccal forms of bacteria - streptococci, staphylococci, micrococci.
Microflora of the alimentary canal. She is the most abundant. In newborn animals, the gastrointestinal tract does not contain microbes. After a few hours, the animal's body is populated by microflora, which can change during life, but basically remains stable until the end of the animal's life. The microflora of the digestive canal is usually divided into facultative, which can vary depending on the feed, conditions of maintenance and operation, and obligate, i.e.. constant, adapted to the environmental conditions of the gastrointestinal tract. The constant microflora includes lactic acid streptococci (Sir. lactis), lactic acid sticks (Bad. acidophilum), Escherichia coli (E. coli).
Microflora of the oral cavity. It is the most abundant and varied. More than 100 types of microorganisms have been found in the oral cavity. Permanent inhabitants of the oral cavity include diplococci, staphylococci, sardines, micrococci, diphtheroids, anaerobes and aerobes, cellulose-destroying bacteria, spirochetes, fungi, yeast, etc.
The diversity of microorganisms depends on the type of animal, the type of feed and how they are used. For example, when feeding with milk, lactic acid microbes and milk microflora prevail. When feeding roughage to herbivores, the number of microbes in the oral cavity is small, when giving them succulent feed, it increases 10 times.
Microflora of the stomach. It is relatively poor in both quantitative and qualitative composition. This is explained by the bactericidal action of acidic gastric juice. In the contents of the stomach, spore-type Bac survive. subtilis, acid-resistant mycobacteria (M. bovis, M. avium), as well as some representatives of sarcina (Sarcina ve; ntriculi), lactic acid bacteria, actinomycetes, enterococci, etc.
With a decrease in acidity, as well as with a disease of the stomach, a rich microflora of putrefactive bacteria, yeasts, fungi, molds and other microorganisms is found in its contents.
In the stomach of a pig, the main representatives of the microflora are lactic acid bacteria, various cocci fermenting carbohydrates, actinomycetes, yeast, spore-forming aerobes; Cl are found. perfringens. The microflora of the horse's stomach is more numerous and varied: closer to the pylorus, it is poor, in the vestibule of the stomach, microbes are concentrated in large numbers; at the bottom of the stomach there are many lactic acid bacteria, no putrefactive ones.
The microflora of the rumen of ruminants is richer. There are many putrefactive bacteria, causative agents of various fermentations. With food, a huge number of various types of epiphytic and soil microflora enter the rumen. They are contained mainly in a vegetative form, their number is from 1 thousand to 10 million microbial bodies, and according to some sources, up to several tens of billions in 1 ml of the contents of the scar.
In the rumen of ruminants, complex microbiological and biochemical processes occur associated with the breakdown of nutrients. Cellulose-destroying microbes are of particular interest: Ruminococcus flavcfaciens, R. albus, Bact. succinogenes, Cl. cellobioparum, Cl. cellolyticum, etc. These microorganisms digest fiber with the help of the cellulose enzyme to glucose, which is easily absorbed by the animal body. Pectins break you down. macerans, Vas. asterosporus, Amylobacter, Granulobacter pectinovorum. Streptococci (Str. bovis, Str. faecalis, etc.) ferment starch, glucose with the formation of lactic acid. Propionic acid bacteria (Propionipcctinovorum, VeilloneUa, Peptosfreptococcus elsdenii, Butyribacterium, E. coli, etc.) ferment lactates with the formation of propionic acid, partially butyric and acetic acid, produce B vitamins. Microbes that inhabit the rumen break down proteins, nitrates, urea synthesize all vitamins except A, E, D.
Microflora of the small intestine. She is the poorest. In the duodenum and jejunum, the activity of cellulose microorganisms is weakened. Here most often live bile-resistant enterococci, acidophilic, spore microbes (Bac. retiformis, Cl. perfringens), actinomycetes, E. coli, etc. The quantitative and qualitative composition of the microflora of the small intestine depends on the type of animals and the nature of their feeding.
Microflora of the large intestine. She is the richest. Permanent inhabitants - enterococci, staphylococci, streptococci, cellulose bacteria, actinomycetes, acidophils, thermophiles, spore forms, yeasts, molds, putrefactive bacteria. The abundance of microorganisms in the colon is due to the presence of large volumes of digested food in them. It has been established that a third of the dry matter of human fecal matter consists of microbes. Microbiological processes in the large intestine do not stop, a number of products of microbial activity are absorbed by the macroorganism. In different species of animals, including birds, bees, the microflora of the large intestine is represented by a variety of associations of microbes, which can be both constant and non-permanent.
In healthy animals, along with normal microflora, in some cases, pathogenic microorganisms are found - causative agents of tetanus, infectious abortion of mares, anthrax, swine erysipelas, pastsrellosis, salmonellosis, anaerobic and other infections.
Microflora of the urinary organs. On the mucous membrane of the genital organs, staphylococci, streptococci, micrococci, diphtheroids, acid-resistant mycobacteria (Mus. smegmae), etc. are found. The main inhabitant of the vaginal mucosa is Bact. vaginale vulgare, which has a pronounced antagonism to other microorganisms. In the physiological state of the urinary tract, the microflora is found only in their outer parts.
The uterus, ovaries, testicles, urinary bladder are sterile in a physiological state. In diseases of the genitourinary organs (metritis, endometritis), the vaginal microflora changes.
Thus, the surface of the body of animals, their open and closed cavities constantly contain a variety of microflora, mostly harmless, but sometimes pathogenic. Under normal conditions, a certain beneficial microbiocenosis is maintained in the body. With a decrease in the resistance of a macroorganism, conditionally pathogenic microorganisms, rapidly developing, cause diseases (pneumonia, enteritis, etc.).
Intizarov Mikhail Mikhailovich, academician of the Russian Academy of Agricultural Sciences, prof..
FOREWORD
When considering ways to combat many infectious diseases of bacterial and viral etiology, they often focus on pathogenic microorganisms - the causative agents of these diseases, and less often pay attention to the accompanying normal microflora of the animal body. But in some cases, it is the ordinary microflora that acquires great importance in the occurrence or development of the disease, contributing to or preventing its manifestation. Sometimes the usual microflora becomes a source of those pathogenic or opportunistic infectious agents that cause endogenous infection, the manifestation of secondary infections, etc. Under other circumstances, the complex of the usual microflora of the animal body blocks the ways and possibilities for the development of an infectious process caused by some pathogenic microorganisms. Therefore, to know the composition, properties, quantitative characteristics, biological significance different groups and representatives of the normal microflora of the body (mammals, including domestic, farm animals and humans) should be doctors, biologists, livestock workers, university professors and scientists.
Introduction
The microflora of the organism of mammals, including agricultural, domestic animals and humans, began to be studied along with the development of microbiology as a science, with the advent of the great discoveries of L. Pasteur, R. Koch, I. I. Mechnikov, their students and employees. So, in 1885, T. Escherich isolated from the feces of children an obligatory representative of the intestinal microflora - Escherichia coli, found in almost all mammals, birds, fish, reptiles, amphibians, insects, etc. After 7 years, the first data appeared on the importance of intestinal sticks for vital activity, health of the macroorganism. S. O. Jensen (1893) found that different types and strains of Escherichia coli can be both pathogenic for animals (causing septic disease and diarrhea in calves) and non-pathogenic, that is, completely harmless and even beneficial inhabitants of the intestines of animals and a person. In 1900, G. Tissier discovered in the feces of newborns bifizhbakter "and - lime: and obligatory representatives of the normal intestinal microflora of the body in all periods of his life. Lactic acid sticks (L. acidophilus) were isolated by Moreau in 1900.
Definitions, terminology
Normal microflora is an open biocenosis of microorganisms found in healthy people and animals (V. G. Petrovskaya, O. P. Marko, 1976). This biocenosis should be characteristic of a completely healthy organism; it is physiological, that is, it helps to maintain the healthy status of the macroorganism, the correct administration of its normal physiological functions. The entire microflora of the animal's body can also be called automicroflora (according to the meaning of the word "auto"), that is, the microflora of any composition (O.V. Chakhava, 1982) of a given organism in normal and pathological conditions.
The normal microflora, associated only with the healthy status of the body, is divided by a number of authors into two parts:
1) obligate, permanent part, formed in phylogenesis and ontogenesis in the process of evolution, which is also called indigenous (i.e., local), autochthonous (indigenous), resident, etc.;
2) optional, or transitory.
Pathogenic microorganisms accidentally penetrating into the macroorganism can periodically be included in the composition of the automicroflora.
Species composition and quantitative characteristicsmicroflora of the most important areas of the animal body
As a rule, dozens and hundreds of species of various microorganisms are associated with the animal organism. They are , as V. G. Petrovskaya and O. P. Marko (1976) write, they are obligate for the organism as a whole. Many types of microorganisms are found in many areas of the body, changing only quantitatively. Quantitative variations are possible in the same microflora depending on the type of mammal. Most animals are characterized by general averages for a number of areas of their body. For example, the distal, lower parts of the gastrointestinal tract are characterized by the following microbial groups detected in the contents of the intestine or feces (Table 1).
At the top of the table 1. only obligate anaerobic microorganisms are given - representatives of the intestinal flora. It has now been established that strictly anaerobic species in the gut account for 95-99%, while all-aerobic and facultative anaerobic species account for the remaining 1-5%.
Despite the fact that tens and hundreds (up to 400) known species microorganisms, there may also exist completely unknown microorganisms. So, in the caecum and colon of some rodents in recent decades it was found the presence of so-called filamentous segmented bacteria, which are very intimately associated with the surface (glycocalix, brush border) of the epithelial cells of the intestinal mucosa. The thin end of these long, filamentous bacteria is recessed between the microvilli of the brush border of the epithelial cells and appears to be fixed there in such a way that it presses the cell membranes. These bacteria can be so numerous that they, like grass, cover the surface of the mucous membrane. These are also strict anaerobes (obligate representatives of the intestinal microflora of rodents), species useful for the body, largely normalizing intestinal functions. However, these bacteria were detected only by bacterioscopic methods (using scanning electron microscopy of sections of the intestinal wall). Filamentous bacteria do not grow on nutrient media known to us, they can only survive on dense agar media for no more than one week) J . P. Koopman et. al., 1984).
The distribution of microorganisms in the gastrointestinal tract
Due to the high acidity of gastric juice, the stomach contains a small number of microorganisms; This is mainly an acid-resistant microflora - lactobacilli, streptococci, yeast, sardines, etc. The number of microbes there is 10 3 / g of content.
Microflora of the duodenum and jejunum
There are microorganisms in the intestinal tract. If they were not in any department, then peritonitis of microbial etiology would not occur when the intestine was injured. Only in the proximal parts of the small intestine there are fewer types of microflora than in the large intestine. These are lactobacilli, enterococci, sardines, mushrooms, in the lower sections the number of bifidobacteria, Escherichia coli increases. Quantitatively, this microflora may differ in different individuals. A minimal degree of contamination is possible (10 1 - 10 3 / g content), and a significant one - 10 3 - 10 4 / g The amount and composition of the microflora of the large intestine are presented in Table 1.
Skin microflora
The main representatives of the skin microflora are diphtherioish (corynebacteria, propionic bacteria), molds, yeasts, spore aerobic bacilli (bacilli), staphylococci (primarily S. epidermidis prevails, but S. aureus is also present on healthy skin in small quantities) .
The microflora of the respiratory tract
On the mucous membranes of the respiratory tract, most of the microorganisms are in the nasopharynx, behind the larynx their number is much less, even less in the large bronchi, and there is no microflora in the depths of the lungs of a healthy body.
In the nasal passages there are diphtheroids, primarily root bacteria, constant staphylococci (resident S. epidermidis), Neisseria, hemophilic bacteria, streptococci (alpha-hemolytic); in the nasopharynx - corynebacteria, streptococci (S. mitts, S. salivarius, etc.), staphylococci, neisseoii, vayloNella, hemophilic bacteria, enterobacteria, bacteroids, fungi, enterococci, lactobacilli, Pseudomonas aeruginosa, aerobic bacilli type B. subtil are more transient is etc.
The microflora of the deeper parts of the respiratory tract has been studied less (A - Halperin - Scott et al., 1982). In humans, this is due to the difficulties in obtaining material. In animals, the material is more accessible for research (killed animals can be used). We studied the microflora of the middle respiratory tract in healthy pigs, including their miniature (laboratory) variety; the results are presented in Table 1. 2.
The first four representatives were detected constantly (100%), less resident (1/2-1/3 cases) were found: lactobacilli (10 2 -10 3), E. coli (10 2 -III 3), mold fungi (10 2 -10 4), yeast. Other authors noted the transient carriage of Proteus, Pseudomonas aeruginosa, Clostridia, representatives of aerobic bacilli. In the same plan, we once identified Bacteroides melaninoge - nicus.
Microflora of the birth canal of mammals
Research recent years, mostly foreign authors (Boyd, 1987; A. B. Onderdonk et al., 1986; J. M. Miller et al., 1986; A. N. Masfari et al., 1986; H. Knothe u. a. 1987) showed that the microflora that colonizes (i.e. inhabits) the mucous membranes of the birth canal is very diverse and rich in species. The components of the normal microflora are widely represented; it contains many strictly anaerobic microorganisms (Table 3).
If we compare the microbial species of the birth canal with the microflora of other areas of the body, we find that the microflora of the mother's birth canal is similar in this respect to the main groups of microbial inhabitants of the body. the future young organism, that is, the obligate representatives of its normal microflora, the animal receives when passing through the birth canal of the mother. Further settlement of the body of a young animal occurs from this brood of an evolutionarily substantiated microflora obtained from the mother. It should be noted that in a healthy female, the fetus in the uterus is sterile until the onset of childbirth.
However, the properly formed (selected in the process of evolution) normal microflora of the animal's body in full inhabits its body not immediately, but in a few days, having time to multiply in certain proportions. V. Brown gives the following sequence of its formation in the first 3 days of a newborn's life: bacteria are found in the very first samples taken from the body of a newborn immediately after birth. So, on the nasal mucosa, coagulase-negative staphylococci (S. epidermidis) were predominant at first; on the mucous membrane of the pharynx - the same staphylococci and streptococci, as well as a small amount of epterobacteria. In the rectum on the 1st day, E. coli, enterococci, the same staphylococci were already found, and by the third day after birth, a microbial biocenosis was established, mostly normal for the normal microflora of the large intestine (W. Braun, F. Spenckcr u. a. , 1987).
Differences in the microflora of the body of different animal species
The above obligate representatives of the microflora are characteristic of most domestic, agricultural mammals and the human body. Depending on the type of animal, the number of microbial groups can rather change, but not their species composition. In dogs, the number of Escherichia coli and lactobacilli in the large intestine is the same as shown in Table. 1. However, bifidobacteria were an order of magnitude lower (10 8 per 1 g), an order of magnitude higher were streptococci (S. lactis, S. mitis, enterococci) and clostridia. In rats and mice (laboratory), the number of lactic acid bacteria (lactobacilli) was increased by the same amount, more streptococci and clostridia. In these animals, there were few Escherichia coli in the intestinal microflora and the number of bifidobacteria was reduced. The number of Escherichia coli is also reduced in guinea pigs (according to V. I. Orlovsky). In the faeces of guinea pigs, according to our research, E. coli were contained within 10 3 -10 4 per 1 g. In rabbits, bacteroids predominated (up to 10 9 -10 10 per 1 g), the number of E. 2 in 1 g) and lactobacilli.
In healthy pigs (according to our data), the microflora of the trachea and large bronchi neither quantitatively nor qualitatively differed significantly from the average indicators and is very similar to the human microflora. Their intestinal microflora was also characterized by a certain similarity.
The microflora of the rumen of ruminants is characterized by specific features. This is largely due to the presence of bacteria - fiber breakers. However, cellulolytic bacteria (and fibrolytic bacteria in general), characteristic of the digestive tract of ruminants, are by no means symbionts of these animals alone. So, in the caecum of pigs and many herbivores, such splitters of cellulose and hemicellulose fibers, common with ruminants, as Bacteroides succi - nogenes, Ruminococcus flavefaciens, Bacteroides ruminicola and others play an important role (V. H. Varel, 1987).
Normal microflora of the body and pathogenic microorganisms
Obligate macroorganisms, which are listed above, are mainly representatives of the pepathogenic microflora. Many of the species included in these groups are even called symbionts of the macroorganism (lactobacilli, bifeldobacteria) and are useful for it. Certain beneficial functions have been identified in many non-pathogenic species of clostridia, bacteroids, eubacteria, enterococci, non-pathogenic Escherichia coli, etc. These and other representatives of the microflora of the body are called "normal" microflora. But less harmless, opportunistic and highly pathogenic microorganisms are included in the microbiocenosis physiological for a macroorganism from time to time. In the future, these pathogens can:
a) exist more or less for a long time in the body
as part of the entire complex of its automicroflora; in such cases, the carriage of pathogenic microbes is formed, but quantitatively, nevertheless, the normal microflora prevails;
b) be forced out (quickly or somewhat later) from the macroorganism by useful symbiotic representatives of the normal microflora and eliminated;
c) multiply by crowding out the normal microflora in such a way that, with a certain degree of colonization of the macroorganism, they can cause the corresponding disease.
In the intestines of animals and humans, for example, in addition to certain types of non-pathogenic clostridia, C. perfringens lives in small numbers. As part of the entire microflora of a healthy animal, the amount of C. perfringens does not exceed 10-15 mln per 1 g. However, under certain conditions, possibly associated with disturbances in the normal microflora, pathogenic C. perfringens multiplies on the intestinal mucosa in large numbers (10 7 -10 9 or more), causing anaerobic infection. In this case, it even displaces the normal microflora and can be detected in the scarified cata of the ileum mucosa in almost pure culture. In a similar way, the development of intestinal coli infection occurs in the small intestine in young animals, only pathogenic types of Escherichia coli multiply just as rapidly there; in cholera, the surface of the intestinal mucosa is colonized by Vibrio cholerae, etc.
Biological role (functional value) of normal microflora
Pathogenic and conditionally pathogenic microorganisms during the life of an animal periodically contact and penetrate into its body, being included in the composition of the general complex of microflora. If these microorganisms cannot immediately cause disease, then they coexist with other microflora of the body for some time, but are more often transient. So, for the oral cavity, from pathogenic and opportunistic facultative transient microorganisms, P, aeruginosa, C. perfringens, C. albicans, representatives (of the genera Esoherichia, Klebsiella, Proteus) can be typical; for the intestines, they are also even more pathogenic enterobacteria, as well as B fragilis, C. tetani, C. sporogenes, Fusobacterium necrophorum, some representatives of the genus Campylobacter, intestinal spirochetes (including pathogenic, conditionally pathogenic) and many others.Skin and mucous membranes are characterized by S. aureus; for respiratory tract - it is also pneumococcus, etc.
However, the role and significance of the useful, symbiotic normal microflora of the body is that it does not easily allow these pathogenic facultative-transient microorganisms into its environment, into the spatial ecological niches already occupied by it. The above representatives of the autochthonous part of the normal microflora were the first, even during the passage of the newborn through the birth canal of the mother, to take their place on the body of the animal, that is, they colonized its skin, gastrointestinal and respiratory tracts, genitals and other areas of the body.
Mechanisms preventing colonization (settlement) of pathogenic microflora of the animal body
It has been established that the largest populations of the autochthonous, obligate part of the normal microflora occupy characteristic places in the intestine, a kind of territory in the intestinal microenvironment (D. Savage, 1970). We studied this ecological feature of bifidobacteria, bacteroids and found that they are not evenly distributed in the chyme throughout the cavity of the intestinal tube, but spread in strips and layers of mucus (mucins) following all the curves of the surface of the mucous membrane of the small intestine. In part, they are adjacent to the surface of epithelial cells of the mucosa. Since bifidobacteria, bacteroids, and others colonize these subregions of the intestinal microenvironment first, they create obstacles for many pathogens that later enter the intestine from approaching and fixing (adhesion) on the mucosa. And this is one of the leading factors, since it has been established that in order to realize their pathogenicity (the ability to cause a disease), any pathogenic microorganisms, including those causing intestinal infections, must adhere to the surface of intestinal epithelial cells, then multiply on it, or, having penetrated deeper, colonize the same or close subregions, in the area of which huge populations have already formed, for example, bifidobacteria. It turns out that in this case, the bifidoflora of a healthy organism shields the intestinal mucosa from some pathogens, limiting their access to the surface of membrane epitheliocytes and to receptors on epithelial cells, on which pathogenic microbes need to be fixed.
For many representatives of the autochthonous part of the normal microflora, a number of mechanisms of antagonism in relation to pathogenic and conditionally pathogenic microflora are known:
Production of volatile fatty acids with a short chain of carbon atoms (they are formed by a strictly anaerobic part of the normal microflora);
Formation of free bile metabolites (lactobacilli, bifidobacteria, bacteroids, enterococci and many others can form them by deconjugating bile salts);
Production of lysozyme (typical of lactobacilli, bifidobacteria);
Acidification of the environment, during the production of organic acids;
Production of colicins and bacteriocins (streptococci, staphylococci, Escherichia coli, Neisseria, propionic bacteria, etc.);
Synthesis of various antibiotic-like substances by many lactic acid microorganisms - Streptococcus lactis, L. acidophilus, L. fermentum, L. brevis, L. helveticus, L. pjantarum, etc.;
Competition of non-pathogenic microorganisms related to pathogenic species with pathogenic species for the same receptors on the cells of the macroorganism, to which their pathogenic relatives should also be fixed;
Absorption by symbiotic microbes from the composition of the normal microflora of some important components and elements of nutritional resources (for example, iron) necessary for the vital activity of pathogenic microbes.
Many of these mechanisms and factors that exist in representatives of the microflora of the animal's body, combined together and interacting, create a kind of barrier effect - an obstacle to the reproduction of opportunistic and pathogenic microorganisms in certain areas of the animal's body. The resistance of a macroorganism to colonization by pathogens, created by its usual microflora, is called colonization resistance. This resistance to colonization by pathogenic microflora is mainly created by a complex of useful species of strictly anaerobic microorganisms that are part of the normal microflora: various representatives of the genera - Bifidobacterium, Bacteroides, Eubacterium, Fusobacterium, Clostridium (non-pathogenic), as well as facultative anaerobes, for example, the genus Lactobacil - lus , non-pathogenic E. coli , S. faecalis, S. faecium and others. It is this part of the strictly anaerobic representatives of the normal microflora of the body that dominates in terms of the number of populations in the entire intestinal microflora within 95-99%. For these reasons, the normal microflora of the body is often considered as an additional factor in the nonspecific resistance of the body of a healthy animal and human.
It is very important to create and observe the conditions under which the settlement of the newborn with normal microflora is formed directly or indirectly. Veterinary specialists, administrative and economic workers, livestock breeders must properly prepare mothers for childbirth, conduct childbirth, ensure colostrum and milk feeding of newborns. It is necessary to carefully treat the state of the normal microflora of the birth canal.
Veterinarians should keep in mind that the normal microflora of the birth canal of healthy females is that physiologically based breeding of beneficial microorganisms, which will determine the correct development of the entire microflora of the body of the future animal. If the birth is uncomplicated, then the microflora should not be disturbed by unjustified therapeutic, preventive and other influences; do not introduce antiseptic agents into the birth canal without sufficiently compelling evidence, deliberately use antibiotics.
conceptaboutdysbacteriosis
There are cases when the evolutionarily established ratio of species in the normal microflora is violated, or the quantitative ratios between the most important groups of microorganisms of the automicroflora of the body change, or the quality of the microbial representatives themselves changes. In this case, dysbacteriosis occurs. And this opens the way for pathogenic and opportunistic representatives of the automicroflora, which can invade or multiply in the body and cause diseases, dysfunctions, etc. The correct structure of the normal microflora that has developed in the process of evolution, its eubiotic state, restrain the opportunistic part within certain limits automicroflora of the animal organism.
Morphofunctional role and metabolic function of the body's automicroflora
Automicroflora affects the macroorganism after its birth in such a way that under its influence the structure and functions of a number of organs in contact with the external environment mature and form. In this way, the gastrointestinal, respiratory, urogenital tracts and other organs acquire their morphofunctional appearance in an adult animal. New area biological spider- Gnotobiology, which has been successfully developing since the time of L. Pasteur, made it possible to very clearly understand that many immunobiological features of an adult, normally developed animal organism are formed under the influence of the automicroflora of its body. Microbial-free animals (gnotobiots) obtained by caesarean section and then kept for a long time in special sterile gnotobibological isolators without any access to them of any viable microflora have features of the embryonic state of the mucous membranes that communicate with the external environment of the organs. Their immunobiological status also retains embryonic features. Observe hypoplasia of the lymphoid tissue in the first place of these organs. Microbial-free animals have fewer immunocompetent cellular elements and immunoglobulins. However, it is characteristic that the organism of such a gnotobiotic animal potentially remains capable of developing immunobiological capabilities, and only because of the absence of antigenic stimuli that come from automicroflora in ordinary animals (starting from birth), it did not undergo a naturally occurring development that affects the entire immune system in in general, and local lymphoid accumulations of the mucous membranes of organs such as the intestines, respiratory tract, eye, nose, ear, etc. Thus, in the process individual development of the animal organism, it is from its automicroflora that the effects follow, including antigenic stimuli, which determine the normal immunomorphofunctional state of an ordinary adult animal.
The microflora of the animal body, in particular the microflora of the gastrointestinal tract, performs important metabolic functions for the body: it affects absorption in the small intestine, its enzymes are involved in the degradation and metabolism of bile acids in the intestine, and forms unusual fatty acids in the digestive tract. Under the influence of microflora, there is a catabolism of some digestive enzymes of the macroorganism in the intestine; enterokinase, alkaline phosphatase are inactivated, decomposed, some immunoglobulins of the digestive tract that have fulfilled their function are decomposed in the large intestine, etc. The microflora of the gastrointestinal tract is involved in the synthesis of many vitamins necessary for the macroorganism. Its representatives (for example, a number of types of bacteroids, anaerobic streptococci, etc.) with their enzymes are able to break down fiber, pectin substances that are indigestible by the animal body on its own.
Some methods of monitoring the state of the microflora of the animal body
Monitoring the state of the microflora in specific animals or their groups will allow timely correction of undesirable changes in an important autochthonous part of the normal microflora, correct violations by artificially introducing beneficial bacterial representatives, such as bifidobacteria or lactobacilli, etc., and prevent the development of dysbacteriosis in very severe forms. Such control is feasible if at the right time to carry out microbiological research species composition and quantitative ratios, primarily in the autochthonous strictly anaerobic microflora of some areas of the animal's body. For bacteriological examination, mucus is taken from the mucous membranes, the contents of organs, or even the tissue of the organ itself.
Taking material. For the study of the large intestine, feces collected specially with the help of sterile tubes - catheters - or in other ways in sterile dishes can be used. Sometimes it is necessary to take the contents of different parts of the gastrointestinal tract or other organs. This is possible mainly after the slaughter of animals. In this way, material can be obtained from the jejunum, duodenum, stomach, etc. Taking segments of the intestine along with their contents makes it possible to determine the microflora of both the alimentary canal cavity and the intestinal wall by preparing scrapings, homogenates of the mucous membrane or intestinal wall. Taking material from animals after slaughter also makes it possible to more fully and comprehensively determine the normal microflora of the generic upper and middle respiratory tract (trachea, bronchi, etc.).
Quantitative research. To determine the quantities of different microorganisms, the material taken from the animal in one way or another is used to prepare 9-10 tenfold dilutions of it (from 10 1 to 10 10) in a sterile saline solution or some (corresponding to the type of microbe) sterile liquid nutrient medium. Then, from each dilution, starting from less to more concentrated, they are sown on the appropriate nutrient media.
Since the studied samples are biological substrates with mixed microflora, it is necessary to select the media so that each satisfies the growth needs of the desired microbial genus or species and simultaneously inhibits the growth of other accompanying microflora. Therefore, it is desirable that the media be selective. By biological role and significance in the normal microflora, its autochthonous strictly anaerobic part is more important. Techniques for its detection are based on the use of appropriate nutrient media and special methods anaerobic cultivation; most of the strictly anaerobic microorganisms listed above can be cultivated on a new, enriched and universal nutrient medium No. 105 by A. K. Baltrashevich et al. (1978). This medium has a complex composition and therefore can satisfy the growth needs of a wide variety of microflora. The recipe for this environment can be found in the manual "Theoretical and practical foundations gnotobiology” (M.: Kolos, 1983). Various options This medium (without the addition of sterile blood, with blood, dense, semi-liquid, etc.) makes it possible to grow many obligate anaerobic species, in anaerobics in a gas mixture without oxygen and outside anaerobics, using a semi-liquid version of medium No. 105 in test tubes.
Bifidobacteria also grow on this medium if 1% lactose is added to it. However, due to the extremely large number of not always available components and the complex composition of medium No. 105, difficulties may arise in its manufacture. Therefore, it is more expedient to use Blaurock's medium, which is no less effective when working with bifidobacteria, but is simpler and more accessible to manufacture (Goncharova G.I., 1968). Its composition and preparation: liver broth - 1000 ml, agar-agar - 0.75 g, peptone - 10 g, lactose - 10 g, cystine - 0.1 g, table salt (x / h) - 5 g. decoction: 500 g of fresh beef liver cut into small pieces, pour 1 liter of distilled water and boil for 1 hour; defend and filter through a cotton-gauze filter, top up with distilled water to the original volume. Melted agar-agar, peptone and cystine are added to this decoction; set pH = 8.1-8.2 with 20% sodium hydroxide and boil for 15 minutes; let stand 30 min And filter. The filtrate is brought up to 1 liter with distilled water and lactose is added to it. Then they are poured into test tubes of 10-15 ml and sterilized with flowing steam fractionally (Blokhina I.N., Voronin E.S. et al., 1990).’
In order to impart selective properties to these media, it is necessary to introduce appropriate agents that inhibit the growth of other microflora. To detect bacteroids - this is neomycin, kanamycin; for spirally curved bacteria (for example, intestinal spirochetes) - spectinomycin; for anaerobic cocci of the genus Veillonella - vancomycin. To isolate bifidobacteria and other gram-positive anaerobes from mixed populations of microflora, sodium azide is added to the media.
To determine the quantitative content of lactobacilli in the material, it is advisable to use Rogosa salt agar. Selective properties are imparted to it by the addition of acetic acid, which creates pH = 5.4 in this medium.
A non-selective medium for lactobacilli can be hydrolyzed milk with chalk: to a liter of pasteurized, skimmed milk (pH -7.4-7.6), which does not contain antibiotic impurities, add 1 g of pancreatin powder and 5 ml of chloroform; shake periodically; put for 72 hours in a thermostat at 40 ° C. Then filtered, set pH = 7.0-7.2 and sterilized at 1 atm. 10 min. The resulting hydrolyzate is diluted with water 1: 2, 45 g of heat-sterilized chalk powder and 1.5-2% agar-agar are added, heated until the agar melts and sterilized again in an autoclave. The medium is slanted before use. Optionally, any selection agent can be added to the medium.
It is possible to identify and determine the level of staphylococci on a fairly simple nutrient medium - glucose salt meat-peptone agar (MPA with 10% salt and 1-2% glucose); enterobacteria - on the Endo medium and other media, the prescriptions of which can be found in any manuals on microbiology; yeast and fungi - on Sabouraud's medium. It is advisable to detect actinomycetes on Krasilnikov's SR-1 medium, consisting of 0.5 dibasic potassium phosphate. 0.5 g of magnesium sulfate, 0.5 g of sodium chloride, 1.0 g of potassium nitrate, 0.01 g of iron sulfate, 2 g of calcium carbonate, 20 g of starch, 15-20 g of agar-agar and up to 1 liter of distilled water . Dissolve all ingredients, mix, heat until agar melts, set pH = 7, filter, pour into test tubes, sterilize in autoclave at 0.5 atm. 15 minutes, mow before sowing.
To detect enterococci, a selective medium (agar-M) is desirable in a simplified version of the following composition: to 1 liter of molten sterile MPA, add 4 g of disubstituted phosphate, dissolved in a minimum amount of sterile distilled water, 400 mg of also dissolved sodium aeide; 2 g of dissolved glucose (or prepared sterile solution of 40% glucose - 5 ml). Move everything. After the mixture has cooled down to about 50 ° C, add TTX (2,3,5-triphenyltetrazolium chloride) - 100 mg dissolved in sterile distilled water into it. Mix, do not sterilize the medium, immediately pour into sterile Petri dishes or test tubes. Entero cocci grow on this medium as small, gray-white colonies. But more often, due to the admixture of TTX, colonies of euterococci acquire a dark cherry color (the entire colony or its center).
Spore aerobic rods (B. subtilis and others) are easily identified after heating the test material at 80°C for 30 minutes. Then the heated material is sown with neither MPA or 1MPB, and after the usual incubation (37°C with access to oxygen), the presence of these bacilli is determined by their growth on the surface of the medium in the form of a film (on the MPB).
Determine the number of corynebacteria in materials from various areas body of an animal can be done using Buchin's medium (available in ready-made form by the Dagestan Institute of Dry Nutrient Media). It can be enriched with up to 5% sterile blood. Neisseria are detected on Bergea's medium with ristomycin: add 1% maltose sterilely dissolved in distilled water to 1 liter of molten Hottinger agar (less desirable MPA) (10 g of maltose can be dissolved in a minimum amount of water and boiled in a water bath), 15 ml 2% a solution of aqueous blue (aniline blue water-soluble), a solution of rystomycin from; calculation 6.25 units. per 1 ml of medium. Mix, do not sterilize, pour into sterile Petri dishes or test tubes. Gram-negative cocci of the genus Neisseria grow in the form of small and medium-sized colonies of blue or of blue color. Hemophilus bacteria can be isolated on chocolate agar (from horse blood) medium with bacitracin as a selective agent. .
Methods for detecting conditionally pathogenic microorganisms (Pseudomonas aeruginosa, Proteus, Klebsiella, etc.). Well known or can be found in most bacteriological manuals.
REFERENCES
Basic
Baltrashevich A. K. et al. Dense medium without blood and its semi-liquid and liquid variants for cultivating bacteroids / Scientific Research Laboratory of Experimental Biological Models of the USSR Academy of Medical Sciences. M. 1978 7 p. Bibliography 7 titles Dep. at VNIIMI 7.10.78, No. D. 1823.
Goncharova G. I. To the method of cultivation of B. bifidum // Laboratory business. 1968. № 2. S. 100-1 D 2.
Guidelines for the isolation and identification of opportunistic enterobacteria and salmonella in acute intestinal diseases of young farm animals / E. N. Blokhina, S. Voronin et al. KhM: MVA, 1990. 32 p.
Petrovskaya V. G., Marko O. P. Human microflora in normal and pathological conditions. Moscow: Medicine, 1976. 221 p.
Chakhava O. V. et al. Microbiological and immunological foundations of gnotobiology. Moscow: Medicine, 1982. 159 p.
Knothe H. u. a. Vaginales Keimspektrum//FAC: Fortschr. antimlkrob, u. Antirieoplastischen Chemotherapie. 1987. Bd. 6-2. S. 233-236.
Koopman Y. P. et al. Associtidn of germ-free rats with different rnicrofloras // Zeitschrift fur Versuchstierkunde. 1984. Bd. 26, No. 2. S. 49-55.
Varel V. H. Activity of fiber-degrading microorganisms in the pig large intestine//J. Anim. Science. 1987. V. 65, N 2. P. 488-496.
Additional
Boyd M. E. Postoperative gynecologic infections//Can. J. Surg. 1987.
V. 30, 'N 1. P. 7-9.
Masfari A. N., Duerden B, L, Kirighorn G. R. Quantitative studies of vaginal bacteria//Genitourin. Med. 1986. V. 62, N 4. P. 256-263.
Methods for quantitative and evaluation of qualitative of vaginal micro-fiora during menstruation / A. B. Onderdonk, G. A. Zamarchi, Y. A. Walsh et al. //Appl. and Environ. microbiology. 1936. V. 51, N 2. P. 333-339.
Miller J. M., Pastorek J. G. The microbiology of premature rupture of the membrans//Clin. obstet. and Gyriecol. 1986. V. 29, N 4. P. 739-757.
Approximately 500 species of microorganisms live in the human body, which make up its normal microflora. . The macroorganism and its microflora under normal conditions are in a state of dynamic equilibrium ( eubiosis), which has developed in the course of evolution.
Open biological systems ( biotopes) that communicate with the environment are - skin, parts of the respiratory tract located up to the glottis, oral cavity, gastrointestinal tract, mucous membranes of the gas, anterior urethra, vagina. They are colonized by microorganisms, among which bacteria dominate. Protozoa and viruses are represented by a much smaller number of species.
Normally free from microorganisms - blood, cerebrospinal fluid, synovial fluid, bone marrow, abdominal cavity, pleural cavity, uterus .
The natural microflora of any biotopes is divided into resident(or permanent) and transitory(or random).
If constant microflora contains representatives specific to a given biotope, then random consists of individuals brought in from outside. So, in the gastrointestinal tract there may be extraneous microorganisms that have been ingested with food or drinks. The skin is most often contaminated with random microflora from the environment. In the trachea, bronchi, lungs, esophagus transient microflora can also be detected.
Permanent microflora specific biotope is relatively stable in composition. At the same time, the composition and physiological role of its constituent microorganisms are far from equivalent. Therefore, two fractions are distinguished in the permanent microflora: obligate And optional.
Obligate microflora is the main component of any microbiocenosis, it counteracts the colonization of the biotope by random microorganisms, participates in the processes of fermentation, immunostimulation, i.e. performs protective and a number of other physiological functions.
Facultative microflora constitutes a smaller part of the permanent inhabitants of the biotope. If the permanent microflora manifests itself mainly as a fermentative activity (i.e., the breakdown of carbohydrates with the formation of acidic products), then the facultative fraction is very actively involved in putrefactive processes (the breakdown of protein substances with the formation of alkaline products).
Animals. The body of a more or less large animal represents a whole world for microorganisms with many ecological niches. Under natural conditions, the body of any animal is inhabited by many microorganisms. Among them there may be random forms, but for many species the body of the animal is the main or only habitat for them. The nature and mechanisms of interactions between microorganisms and a macroorganism are diverse and play a decisive role in the life and evolution of many types of microorganisms. For an animal, microorganisms are an important ecological factor that determines many aspects of its evolutionary changes. From modern positions, normal microflora is considered as a set of microbiocenoses occupying numerous ecological niches on the skin and mucous membranes of all body cavities open to the external environment. In a significant part, the microflora is the same in all animals in the compared biotopes, but there are individual differences in the composition of the microbiocenosis. The automicroflora of a healthy animal remains constant and is maintained by homeostasis. Tissues and organs that do not communicate with the external environment are sterile. The organism and its normal microflora constitute a single ecological system: the microflora serves as a kind of "extracorporeal organ" that plays an important role in the life of the animal. Being a biological factor of protection, the normal microflora is the barrier, after the breakthrough of which the inclusion of non-specific defense mechanisms is induced.
Antagonism microorganisms - a type of non-symbiotic relationship of microorganisms, in which one strain completely suppresses or slows down the growth of another. It can be observed both in natural conditions and in artificial (laboratory). Microorganisms-antagonists can belong to any taxonomic groups. As a rule, antagonism occurs when a microorganism releases chemicals with antibiotic properties that inhibit the growth and vital activity of other microorganisms. In this case, the microorganism that releases the chemical gets a competitive advantage. Other mechanisms are also possible. Antagonism of microorganisms is widespread in the soil, where there is constant competition for space and nutrients. Example: suppression of the plague bacillus with Pseudomonas aeruginosa.
Commensalism(from lat. com- "with", "together" and mensa- "table", "meal"; literally "at the table", "at the same table"; previously - companionship) - a way of coexistence (symbiosis) of two different types of living organisms, in which one of the partners of this system (commensal) imposes on the other (host) the regulation of its relations with the external environment, but does not enter into close relationships with it. Example: A fish stuck to a shark.
Microbial biocenoses found in the body of humans and animals have formed in the process of evolution and play an important role in the functional activity of various organs of humans or animals.
The formation of the quantitative and qualitative composition of the microflora in the macroorganism is regulated by complex antagonistic and synergistic relationships between its individual representatives in the composition of bioceoses, and is also controlled physiological factors macroorganism in the dynamics of its development.
The microflora of the body of both humans and animals can be divided into two groups: constant normal (obligate) and random (optional).
The usual, normal group includes microorganisms that are maximally adapted for existence in the host's body and are naturally found in its cavities and organs. These microorganisms are represented by saprophytes (non-pathogenic) and conditionally pathogenic species.
Facultative (transient) microflora is temporary and optional. Its presence is determined by the intake of microbes from the environment and the state of the host's immune system. The species composition of the normal microflora of humans and animals (biocenosis) was formed as a result of the interaction of micro- and macroorganism in the process of evolution. A natural consequence of this process was that the totality of microbial species characteristic of individual organs and cavities of the body became a necessary condition for the normal functioning of the body. Violation of the biocenosis, the appearance of unusual microorganisms, causes the development of the disease.
The fetus of a person or animal during fetal development is sterile.
The human and animal organism, starting from the first minutes of earthly life, constantly comes into contact with the environment and is populated by microorganisms living in this environment.
Immediately after birth, a wide variety of microorganisms enter the skin and mucous membranes of the newborn, as well as in the cavities in contact with the external environment. First of all, they fall from the hands of medical staff and from the air. Some of them quickly die or are removed from the body, others take root in certain organs or parts of the body and the formation of normal microflora of the body begins.
During the life of a person or animal, the nature of this microflora changes, but in general it is constant and characteristic of individual organs.
The internal tissues and organs of humans and animals (blood, brain, cerebrospinal fluid, liver, uterus, bladder cavity) are usually sterile. The same organs and tissues that communicate with the environment contain microorganisms.
A lot of microbes live on the skin and hairline - here you can find almost all representatives of the microflora of the environment. Among them, cocci, Escherichia, diphtheroids, spore-forming bacilli, various opportunistic and even pathogenic bacteria, yeast-like and radiant fungi, etc.
The total number of microbes on the surface of the skin reaches the number 1010 degrees.
Microorganisms that have fallen on clean healthy skin usually die from the action of bactericidal substances secreted by the skin, as well as from antagonist bacteria that constantly live on the skin. Pollution of the skin contributes to the accumulation of pathogenic microorganisms on it. Their nutrient substrate is the secretions of the sebaceous and sweat glands, dead cells, decay products.
It is very important to constantly keep the skin clean, because clean and undamaged skin, on the one hand, mechanically prevents the penetration of microorganisms into the body of the macroorganism. On the other hand, it contributes to the death of microbial cells as a result of the release of bactericidal substances by the skin. When the skin is contaminated, the release of bactericidal substances decreases or stops altogether.
With the first breath of a newborn, microbes are introduced into the respiratory tract and take root there. Most of them are in the nasal cavity, much less in the larynx, even less in the trachea and large bronchi. Small bronchi are free from microorganisms, but if single microbial cells get there, they quickly die.
The permanent inhabitants of the upper respiratory tract (nasal cavity, larynx and bronchi) are mainly cocci (staphylococci, streptococci, pneumococci). There are diphtheroids and other microorganisms, most often harmless commensals (cohabitants).
Obligate microorganisms of the mucous respiratory tract in animals are staphylo- and streptococci, sarcins, pneumococci, pasteurella, mycoplasmas.
The ciliated epithelium of the mucous membrane of the upper respiratory tract plays an important role in protecting the respiratory organs from microorganisms.
The microflora of the mucous membrane of the eye is very poor, due to the action of lysozyme contained in tears. On the mucous membrane of the eye, most often you can find non-pathogenic cocci, less often spores of yeast-like and mold fungi, as well as B. xerosis, morphologically very similar to true diphtheria bacteria.
The microflora of the digestive tract of humans and animals is extremely abundant and diverse.
Already with the first portions of mother's milk, microbes enter the oral cavity, and then penetrate into the stomach and intestines.
The oral cavity is a very good reservoir for the development of microorganisms. There is everything necessary for their development - a measured temperature, the presence of moisture, an abundance of nutrients, an alkaline pH of saliva.
In places where food debris accumulates - between the teeth, on the gums, there are a lot of microbes. A wide variety of microorganisms live in the human oral cavity - cocci, lactic acid bacteria, diphtheroids, anaerobes, actinomycetes, yeast-like fungi, non-pathogenic spirochetes and protozoa, etc. 1 ml of saliva contains millions of microbial cells. And although saliva contains the bactericidal substance lysozyme, which has a detrimental effect on microorganisms, many types of bacteria have taken root in the oral cavity, acquired resistance to lysozyme and multiply well in its presence.
The mucous plaque of white, yellow, red or brown color, which often appears on the surface of the teeth, consists entirely of microbes, which are the main culprits of tooth decay.
Among the inhabitants of the oral cavity of animals are micrococci, spirochetes, mycoplasmas, lactic acid bacteria.
The microflora of the gastrointestinal tract is different in different departments. Juices of the digestive glands enter different sections of the gastrointestinal tract and food enters different stages of digestion, which causes the creation of its own specific environment in each section. Each section of the digestive canal has its own microbes, accustomed to existing in these conditions.
In the stomach of humans and animals, only acid-resistant microorganisms survive, including lactic acid microorganisms, as well as spores of bacteria, fungi, and actinomycetes. Only with a decrease in the acidity of gastric juice in the stomach do yeast, sarcins, spore-forming bacilli Bac.subtilis, Bac.mesentericus, putrefactive and other bacteria begin to multiply.
In the proventriculus of ruminants, ciliates, cocci, bacteria that break down fiber and carbohydrates, synthesize vitamins and proteins are found.
In the small intestine, despite the alkaline pH of the environment, there are few microorganisms, just like in the stomach. This is due to the unfavorable action of enzymes for microorganisms. Here only those of them that are resistant to the action of bile can manifest their vital activity. These include some types of lactic acid and spore bacteria, yeasts and radiant fungi.
In the large intestine, semi-digested food residues linger longer than in the small intestine. The bactericidal action of digestive juices is not affected here, and microbes multiply freely and abundantly. Up to 260 species of microorganisms have been found in the large intestine.
All microorganisms that are found in the large intestine can be divided into casual and permanent inhabitants.
The permanent inhabitants of the large intestine include microbes that break down cellulose and hydrolyze starch, lactic acid bacteria. In this section of the intestine, varieties of Escherichia coli (E.coli), clostridia (Cl.perfringens, Cl.sporogenes) are widely represented, enterococci, streptococci and staphylococci, bacteria of the genus Citrobacter are found. Putrefactive bacteria (Proteus vulgaris), yeast, protozoa, campylobacter, spores of bacilli, atinomycetes and imperfect fungi, viruses and other microorganisms are found.
The microflora of the large intestine of both humans and animals is changing.
So, lactic acid bacteria predominate in infants, in adults in most cases bacteroids, bifidobacteria, Escherichia coli, streptococci, etc.
In the area of the genitourinary organs, microflora is found only in their outer parts. Among the common microbes of the external parts of the genitourinary organs, cocci, acid-resistant bacteria, diphtheroids, sarcins, mycoplasmas, fusimorphic bacteria, listeria, non-pathogenic spirochetes, Escherichia, Klebsiella, Proteus, andids, campylobacter, mycobacteria are found.
The cavity of the bladder and uterus, both in humans and in animals, are sterile in their normal state.
The microflora of the vagina changes throughout life. In girls, the coccal flora predominates. In adult women - acidophilic gram-positive vaginal bacillus - Bact.doderleini.
The normal microflora of the human and animal body has been and is being studied by many scientists, but so far its significance for the macroorganism has not been fully disclosed.