Presentation on the topic of types of bacteria. Some types of pathogenic bacteria

Bacteria is the most ancient organism on earth, as well as the simplest in its structure. It consists of only one cell, which can only be seen and studied under a microscope. A characteristic feature of bacteria is the absence of a nucleus, which is why bacteria are classified as prokaryotes.

Some species form small groups of cells; such clusters may be surrounded by a capsule (sheath). The size, shape, and color of bacteria are highly dependent on the environment.

In terms of shape, bacteria are divided into: rod-shaped (bacilli), spherical (cocci) and convoluted (spirilla). There are also modified ones - cubic, C-shaped, star-shaped. Their sizes range from 1 to 10 microns. Certain types of bacteria can actively move with the help of flagella. The latter sometimes exceed the size of the bacterium itself twice.

Types of bacteria forms

For movement, bacteria use flagella, the number of which is different - one, a pair, a bundle of flagella. The location of the flagella is also different - on one side of the cell, on the sides, or evenly distributed over the entire plane. Also, one of the ways of movement is considered to be sliding due to the mucus that the prokaryote is covered with. Most have vacuoles inside the cytoplasm. Adjusting the capacity of the gas in the vacuoles helps them move up or down in the liquid, as well as move through the air channels of the soil.

Scientists have discovered more than 10 thousand varieties of bacteria, but according to the assumptions of scientific researchers, there are more than a million species of them in the world. general characteristics bacteria makes it possible to determine their role in the biosphere, as well as to study the structure, types and classification of the kingdom of bacteria.

habitats

The simplicity of the structure and the speed of adaptation to environmental conditions helped bacteria to spread over a wide range of our planet. They exist everywhere: water, soil, air, living organisms - all this is the most acceptable habitat for prokaryotes.

Bacteria have been found both at the south pole and in geysers. They are on the ocean floor, as well as in the upper layers of the Earth's air shell. Bacteria live everywhere, but their number depends on favorable conditions. For example, a large number of bacterial species live in open water bodies, as well as in the soil.

Structural features

A bacterial cell is distinguished not only by the fact that it does not have a nucleus, but also by the absence of mitochondria and plastids. The DNA of this prokaryote is located in a special nuclear zone and has the form of a nucleoid closed in a ring. In bacteria, the cell structure consists of a cell wall, a capsule, a capsule-like membrane, flagella, pili, and a cytoplasmic membrane. Internal structure make out the cytoplasm, granules, mesosomes, ribosomes, plasmids, inclusions and nucleoid.

The bacterial cell wall performs the function of defense and support. Substances can freely flow through it due to permeability. This shell contains pectin and hemicellulose. Some bacteria secrete a special mucus that can help protect against drying out. Mucus forms a capsule - a polysaccharide along chemical composition. In this form, the bacterium is able to tolerate even very high temperatures. It also performs other functions, for example, sticking to any surfaces.

On the surface of the bacterial cell are thin protein villi - pili. There may be a large number of them. Pili help the cell to transfer genetic material, and also provide adhesion to other cells.

Under the plane of the wall is a three-layer cytoplasmic membrane. It guarantees the transport of substances, and also plays a significant role in the formation of spores.

The cytoplasm of bacteria is 75 percent made from water. The composition of the cytoplasm:

• fishsomes;
• mesosomes;
• amino acids;
• enzymes;
• pigments;
• sugar;
• granules and inclusions;
• nucleoid.

Metabolism in prokaryotes is possible, both with the participation of oxygen and without it. Most of them feed on ready-made nutrients of organic origin. Very few species are capable of synthesizing organic substances from inorganic ones themselves. These are blue-green bacteria and cyanobacteria, which played a significant role in shaping the atmosphere and saturating it with oxygen.

reproduction

In conditions favorable for reproduction, it is carried out by budding or vegetatively. Asexual reproduction occurs in the following sequence:

1. The bacterial cell reaches its maximum volume and contains the necessary supply of nutrients.
2. The cell lengthens, a partition appears in the middle.
3. Within the cell, a division of the nucleotide occurs.
4. DNA main and separated diverge.
5. The cell is divided in half.
6. Residual formation of daughter cells.

With this method of reproduction, there is no exchange of genetic information, so all daughter cells will be an exact copy of the mother.

The process of bacterial reproduction in favorable conditions more interesting. Scientists learned about the ability of bacteria to reproduce sexually relatively recently - in 1946. Bacteria do not have a division into female and germ cells. But they have different DNA. Two such cells, when approaching each other, form a channel for the transfer of DNA, an exchange of sites occurs - recombination. The process is quite long, the result of which are two completely new individuals.

Most bacteria are very difficult to see under a microscope because they do not have their own color. Few varieties are purple or green due to their content of bacteriochlorophyll and bacteriopurpurine. Although if we consider some colonies of bacteria, it becomes clear that they release colored substances into the environment and acquire a bright color. In order to study prokaryotes in more detail, they are stained.

Classification

The classification of bacteria can be based on indicators such as:

• The form
• way to travel;
• way to get energy;
• waste products;
• degree of danger.

Bacteria symbionts live in partnership with other organisms.

Bacteria saprophytes live on already dead organisms, products and organic waste. They contribute to the processes of decay and fermentation.

Decay cleanses nature of corpses and other wastes of organic origin. Without the process of decay, there would be no cycle of substances in nature. So what is the role of bacteria in the cycling of matter?

Decay bacteria are an assistant in the process of breaking down protein compounds, as well as fats and other compounds containing nitrogen. Having carried out a complex chemical reaction, they break bonds between the molecules of organic organisms and capture protein molecules, amino acids. Splitting, the molecules release ammonia, hydrogen sulfide and other harmful substances. They are poisonous and can cause poisoning in humans and animals.

Decay bacteria multiply rapidly in favorable conditions for them. Since these are not only beneficial bacteria, but also harmful ones, in order to prevent premature decay in products, people have learned to process them: dry, pickle, salt, smoke. All of these treatments kill bacteria and prevent them from multiplying.

Fermentation bacteria with the help of enzymes are able to break down carbohydrates. People noticed this ability in ancient times and use such bacteria to make lactic acid products, vinegars, and other food products to this day.

Bacteria, working in conjunction with other organisms, do very important chemical work. It is very important to know what types of bacteria are and what benefits or harm they bring to nature.

Significance in nature and for man

It has already been noted above great importance many types of bacteria (during the processes of decay and various types x fermentation), i.e. fulfillment of a sanitary role on Earth.

Bacteria also play a huge role in the cycle of carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, calcium and other elements. Many types of bacteria contribute to the active fixation of atmospheric nitrogen and convert it into an organic form, contributing to an increase in soil fertility. Of particular importance are those bacteria that decompose cellulose, which are the main source of carbon for the vital activity of soil microorganisms.

Sulfate-reducing bacteria are involved in the formation of oil and hydrogen sulfide in therapeutic mud, soils and seas. Thus, the layer of water saturated with hydrogen sulfide in the Black Sea is the result of the vital activity of sulfate-reducing bacteria. The activity of these bacteria in soils leads to the formation of soda and soda salinization of the soil. Sulfate-reducing bacteria convert nutrients in rice plantation soils into a form that becomes available to the roots of the crop. These bacteria can cause corrosion of metal underground and underwater structures.

Thanks to the vital activity of bacteria, the soil is freed from many products and harmful organisms and rich in valuable nutrients. Bactericidal preparations are successfully used to combat many types of insect pests (corn borer, etc.).

Many types of bacteria are used in various industries to produce acetone, ethyl and butyl alcohols, acetic acid, enzymes, hormones, vitamins, antibiotics, protein and vitamin preparations, etc.

Without bacteria, processes are impossible in tanning leather, drying tobacco leaves, making silk, rubber, processing cocoa, coffee, urinating hemp, flax and other bast-fiber plants, sauerkraut, cleaning Wastewater, metal leaching, etc.

Structure

Bacteria are very small living organisms. They can only be seen under a very high magnification microscope. All bacteria are unicellular. The internal structure of a bacterial cell is not like the cells of plants and animals. They do not have a nucleus or plastids. The nuclear substance and pigments are present, but in a "dispersed" state. The form is varied.

The bacterial cell is dressed in a special dense shell - the cell wall, which performs protective and supporting functions, and also gives the bacterium a permanent, characteristic shape. The cell wall of a bacterium resembles the shell of a plant cell. It is permeable: through it, nutrients freely pass into the cell, and metabolic products go out into the environment. Often, an additional protective layer of mucus is produced on top of the cell wall in bacteria - a capsule. The thickness of the capsule can be many times greater than the diameter of the cell itself, but it can be very small. The capsule is not an obligatory part of the cell, it is formed depending on the conditions in which the bacteria enter. It keeps bacteria from drying out.

On the surface of some bacteria there are long flagella (one, two or many) or short thin villi. The length of the flagella can be many times greater than the size of the body of the bacterium. Bacteria move with the help of flagella and villi.

Inside the bacterial cell is a dense immobile cytoplasm. It has a layered structure, there are no vacuoles, so various proteins (enzymes) and reserve nutrients are located in the very substance of the cytoplasm. Bacterial cells do not have a nucleus. In the central part of their cells, a substance carrying hereditary information is concentrated. Bacteria - nucleic acid - DNA. But this substance is not framed in the nucleus.

The internal organization of a bacterial cell is complex and has its own specific features. The cytoplasm is separated from the cell wall by the cytoplasmic membrane. In the cytoplasm, the main substance, or matrix, ribosomes and a small number of membrane structures that perform a variety of functions (analogues of mitochondria, endoplasmic reticulum, Golgi apparatus) are distinguished. The cytoplasm of bacterial cells often contains granules various shapes and sizes. The granules may be composed of compounds that serve as a source of energy and carbon. Droplets of fat are also found in the bacterial cell.

Spore formation

Spores form inside the bacterial cell. In the process of spore formation, a bacterial cell undergoes a series of biochemical processes. The amount of free water in it decreases, enzymatic activity decreases. This ensures the resistance of spores to adverse environmental conditions (high temperature, high salt concentration, drying, etc.). Spore formation is characteristic of only a small group of bacteria. Spores are not an essential stage in the life cycle of bacteria. Sporulation begins only with a lack of nutrients or the accumulation of metabolic products. Bacteria in the form of spores can remain dormant for a long time. Bacterial spores withstand prolonged boiling and very long freezing. When favorable conditions occur, the dispute germinates and becomes viable. Bacterial spores are adaptations for survival in adverse conditions. Spores in bacteria serve to endure adverse conditions. They are formed from the inside of the contents of the cell. In this case, a new, denser shell is formed around the spore. Spores can be very low temperatures(up to - 273 ° C) and very high. Spores are not killed by boiling water.

Food

Many bacteria have chlorophyll and other pigments. They carry out photosynthesis, like plants (cyanobacteria, purple bacteria). Other bacteria get energy from inorganic substances- sulfur, iron compounds and others, but the source of carbon, as in photosynthesis, is carbon dioxide.

reproduction

Bacteria reproduce by dividing one cell into two. Having reached a certain size, the bacterium divides into two identical bacteria. Then each of them begins to feed, grows, divides, and so on. After elongation of the cell, a transverse septum is gradually formed, and then the daughter cells diverge; in many bacteria, under certain conditions, cells after division remain connected in characteristic groups. In this case, depending on the direction of the division plane and the number of divisions, different forms arise. Reproduction by budding occurs in bacteria as an exception.

Under favorable conditions, cell division in many bacteria occurs every 20-30 minutes. With such rapid reproduction, the offspring of one bacterium in 5 days is able to form a mass that can fill all the seas and oceans. A simple calculation shows that 72 generations (720,000,000,000,000,000,000 cells) can be formed per day. If translated into weight - 4720 tons. However, this does not happen in nature, since most bacteria quickly die under the action of sunlight, during drying, lack of food, heating up to 65-100ºС, as a result of the struggle between species, etc.

The role of bacteria in nature. Distribution and ecology

Bacteria are ubiquitous: in water bodies, air, soil. There are the least of them in the air (but not in crowded places). In the waters of rivers there can be up to 400,000 of them in 1 cm 3, and in the soil - up to 1,000,000,000 in 1 g. Bacteria have different attitudes towards oxygen: for some it is necessary, for others it is destructive. For most bacteria, temperatures between +4 and +40 °C are most favorable. Direct sunlight kills many bacteria.

Occurring in huge numbers (the number of their species reaches 2500), bacteria play an exceptionally important role in many natural processes. Together with fungi and soil invertebrates, they participate in the decomposition of plant residues (falling leaves, branches, etc.) to humus. The activity of saprophytic bacteria leads to the formation mineral salts which are taken up by plant roots. Nodule bacteria living in the tissues of the moth roots, as well as some free-living bacteria, have a remarkable ability to assimilate atmospheric nitrogen, which is inaccessible to plants. Thus, bacteria participate in the cycle of substances in nature.

Soil microflora. The number of bacteria in the soil is extremely high - hundreds of millions and billions of individuals in 1 gram. They are much more abundant in soil than in water and air. The total number of bacteria in soils varies. The number of bacteria depends on the type of soil, their condition, the depth of the layers. On the surface of soil particles, microorganisms are located in small microcolonies (20-100 cells each). Often they develop in the thicknesses of clots of organic matter, on living and dying plant roots, in thin capillaries and inside lumps. Soil microflora is very diverse. Different physiological groups of bacteria are found here: putrefactive, nitrifying, nitrogen-fixing, sulfur bacteria, etc. among them there are aerobes and anaerobes, spore and non-spore forms. Microflora is one of the factors of soil formation. The area of ​​development of microorganisms in the soil is the zone adjacent to the roots of living plants. It is called the rhizosphere, and the totality of microorganisms contained in it is called the rhizosphere microflora.

Microflora of water bodies. Water is a natural environment where microorganisms grow in large numbers. Most of them enter the water from the soil. A factor that determines the number of bacteria in water, the presence of nutrients in it. The cleanest are the waters of artesian wells and springs. Open reservoirs and rivers are very rich in bacteria. The largest number bacteria is found in the surface layers of the water, closer to the shore. With increasing distance from the coast and increasing depth, the number of bacteria decreases. Pure water contains 100-200 bacteria in 1 ml, and contaminated - 100-300 thousand or more. There are many bacteria in the bottom silt, especially in the surface layer, where the bacteria form a film. There are a lot of sulfur and iron bacteria in this film, which oxidize hydrogen sulfide to sulfuric acid and thereby prevent fish from dying. There are more spore-bearing forms in the silt, while non-spore-bearing forms predominate in the water. In terms of species composition, the water microflora is similar to the soil microflora, but specific forms are also found. Destroying various wastes that have fallen into the water, microorganisms gradually carry out the so-called biological purification of water.

Air microflora. Air microflora is less numerous than soil and water microflora. Bacteria rise into the air with dust, can stay there for a while, and then settle to the surface of the earth and die from lack of nutrition or under the influence of ultraviolet rays. The number of microorganisms in the air depends on the geographic area, terrain, season, dust pollution, etc. Each speck of dust is a carrier of microorganisms. Most bacteria in the air over industrial enterprises. The air in the countryside is cleaner. The cleanest air is over forests, mountains, snowy spaces. The upper layers of the air contain fewer germs. In the air microflora there are many pigmented and spore-bearing bacteria that are more resistant than others to ultraviolet rays.

Microflora of the human body. The body of a person, even a completely healthy one, is always a carrier of microflora. When the human body comes into contact with air and soil, a variety of microorganisms, including pathogens (tetanus bacilli, gas gangrene, etc.), settle on clothing and skin. The exposed parts are most frequently contaminated human body. E. coli, staphylococci are found on the hands. There are over 100 types of microbes in the oral cavity. The mouth, with its temperature, humidity, nutrient residues, is an excellent environment for the development of microorganisms. The stomach has an acidic reaction, so the bulk of microorganisms in it die. Beginning with small intestine the reaction becomes alkaline, i.e. favorable for microbes. The microflora in the large intestine is very diverse. Each adult excretes about 18 billion bacteria daily with excrement, i.e. more individuals than people on the globe. Internal organs that do not connect with the external environment (brain, heart, liver, bladder etc.), are usually free from microbes. Microbes enter these organs only during illness.

The importance of bacteria in human life

Fermentation processes are of great importance; this is what is generally called the decomposition of carbohydrates. So, as a result of fermentation, milk turns into kefir and other products; ensiling fodder is also fermentation. Fermentation also occurs in the human intestine. Without the appropriate bacteria (such as E. coli), the intestines cannot function normally. Rotting, useful in nature, is highly undesirable in everyday life (for example, damage meat products). Fermentation (for example, souring milk) is not always useful either. So that the products do not deteriorate, they are salted, dried, canned, kept in refrigerators. Thus, the activity of bacteria is reduced.

Pathogenic bacteria

Bacteria are very small, incredibly ancient, and to some extent quite simple microorganisms. According to modern classification they were isolated in a separate domain of organisms, which indicates a significant difference between bacteria and other life forms.

Bacteria are the most common and, accordingly, the most numerous living organisms, they are, without exaggeration, ubiquitous and feel great in any environment: water, air, earth, as well as inside other organisms. So in one drop of water, their number can reach several million, and in the human body there are about ten more of them than all of our cells.

Who are bacteria?

These are microscopic, predominantly unicellular organisms, the main difference of which is the absence of a cell nucleus. The basis of the cell, the cytoplasm, contains ribosomes and a nucleoid, which is the genetic material of bacteria. All this is separated from the outside world by a cytoplasmic membrane or plasmalemma, which in turn is covered with a cell wall and a denser capsule. Some types of bacteria have external flagella, their number and size can vary greatly, but the purpose is always the same - with their help, the bacteria move.

Structure and contents of a bacterial cell

What are bacteria?

Shapes and sizes

The shapes of different types of bacteria are very variable: they can be round, rod-shaped, convoluted, stellate, tetrahedral, cubic, C- or O-shaped, and also irregular.

Bacteria vary greatly in size. So, Mycoplasma mycoides - the smallest species in the whole kingdom has a length of 0.1 - 0.25 micrometers, and the largest bacterium Thiomargarita namibiensis reaches 0.75 mm - it can even be seen with the naked eye. On average, the sizes range from 0.5 to 5 microns.

Metabolism or metabolism

In matters of obtaining energy and nutrients, bacteria exhibit extreme diversity. But at the same time, it is quite easy to generalize them, dividing them into several groups.

According to the method of obtaining nutrients (carbons), bacteria are divided into:

• autotrophs- organisms capable of independently synthesizing all the organic substances they need for life;
• heterotrophs- organisms that are able to transform only ready-made organic compounds, and therefore need the help of other organisms that would produce these substances for them.

By way of obtaining energy:

• phototrophs organisms that produce energy through photosynthesis
• chemotrophs- Organisms that produce energy through various chemical reactions.

How do bacteria reproduce?

Growth and reproduction in bacteria are closely related. Having reached a certain size, they begin to multiply. In most types of bacteria, this process can proceed extremely quickly. Cell division, for example, can take less than 10 minutes, while the number of new bacteria will grow exponentially, since each new organism will be divided into two.

There are 3 different types of reproduction:

• division- one bacterium is divided into two absolutely genetically identical.
• budding- one or more buds (up to 4) are formed at the poles of the parent bacterium, while the mother cell ages and dies.
• primitive sexual process- part of the DNA of the parent cells is transferred to the daughter, and a bacterium appears with a fundamentally new set of genes.

The first type is the most common and fastest, the last one is incredibly important, not only for bacteria, but for all life in general.

Bacteria are dangerous and useful, their role in human life

Bacterial infections are considered one of the most dangerous - humanity has been fighting pathogenic microorganisms for more than one century. However, not all bacteria are unambiguous enemies for humans. Many species are vital - they ensure proper digestion and even help the immune system defend itself against other microorganisms. MedAboutMe will tell you how to distinguish between bad and good bacteria, what to do if they are found in the analysis, and how to properly treat the diseases they cause.

Bacteria and man

It is believed that bacteria appeared on Earth more than 3.5 billion years ago. It was they who became active participants in creating suitable conditions for life on the planet, and throughout their existence they have been actively involved in important processes. For example, it is thanks to bacteria that the decay of the organic remains of animals and plants occurs. They also created fertile soil on Earth.

And since bacteria live literally everywhere, the human body is no exception. On the skin, mucous membranes, in the gastrointestinal intestinal tract, nasopharynx, urogenital tract is inhabited by many microorganisms that interact with humans in different ways.

In the womb, the placenta protects the fetus from the penetration of bacteria, the population of the body occurs in the first days of life:

• The first bacteria the child receives, passing through the birth canal of the mother.
• Microorganisms enter the gastrointestinal tract during feeding breast milk. Here, among more than 700 species, lactobacilli and bifidobacteria predominate (the benefits are described in the table of bacteria at the end of the article).
• oral cavity inhabited by staphylococci, streptococci and other microbes, which the child also receives with food and in contact with objects.
• On the skin, the microflora is formed from bacteria that predominate in the people around the child.

The role of bacteria for a person is invaluable, if already in the first months the microflora does not form normally, the child will lag behind in development and often get sick. After all, without symbiosis with bacteria, the body cannot function.

Beneficial and harmful bacteria

Everyone is well aware of the concept of dysbacteriosis - a condition in which the natural microflora in the human body is disturbed. Dysbacteriosis is a serious factor in lowering the immune defense, the development of various inflammations, disruption of the digestive tract and other things. The absence of beneficial bacteria contributes to the reproduction of pathogenic organisms, and fungal infections often develop against the background of dysbacteriosis.

At the same time, in environment There are many pathogenic microbes that can cause serious illness. The most dangerous are those types of bacteria that in the process of life are capable of producing toxins (exotoxins). It is these substances that are today considered one of the most powerful poisons. These microorganisms cause dangerous infections:

• Botulism.
• Gas gangrene.
• diphtheria.
• Tetanus.

In addition, the disease can also be provoked by bacteria that live in the human body under normal conditions, and when the immune system is weakened, they begin to become more active. The most popular pathogens of this kind are staphylococci and streptococci.

Bacteria life

Bacteria are full-fledged living organisms with a size of 0.5-5 microns, which are able to actively multiply in a suitable environment. Some of them need oxygen, others do not. There are motile and non-motile types of bacteria.

Bacteria cell

Most bacteria living on Earth are single-celled organisms. Mandatory components of any microbe:

• Nucleoid (nucleus-like region containing DNA).
• Ribosomes (carry out the synthesis of proteins).
• Cytoplasmic membrane (separates the cell from the external environment, maintains homeostasis).

Also, some bacterial cells have a thick cell wall, which additionally protects them from damage. Such organisms are more resistant to drugs and antigens that the human immune system produces.

There are bacteria with flagella (mototrichia, lophotrichia, peritrichia), due to which microorganisms are able to move. However, scientists have also recorded another type of movement characteristic of microbes - the sliding of bacteria. Moreover, recent studies show that it is inherent in those species that were previously considered immobile. For example, scientists from the University of Nottingham and Sheffield have shown that methicillin-resistant Staphylococcus aureus (one of the main representatives of the class of superbugs) is able to move without the help of flagella and villi. And this, in turn, significantly affects the understanding of the mechanisms of the spread of a dangerous infection.

Bacterial cells can be of the following forms:

• Round (cocci, from other Greek κόκκος - "grain").
• Rod-shaped (bacilli, clostridia).
• Sinuous (spirochetes, spirilla, vibrios).

Many microorganisms are able to stick together in colonies, so more often scientists and doctors isolate bacteria not by the structure of the element, but by the type of compounds:

• Diplococci are cocci connected in pairs.
• Streptococci are cocci that form chains.
• Staphylococci are cocci that form clusters.
• Streptobacteria are rod-shaped microorganisms connected in a chain.

Reproduction of bacteria

The vast majority of bacteria reproduce by division. The rate of spread of the colony depends on the external conditions and the type of microorganism itself. So, on average, one bacterium is able to divide every 20 minutes - it forms 72 generations of offspring per day. For 1-3 days, the number of descendants of one microorganism can reach several million. In this case, the reproduction of bacteria may not be so fast. For example, the process of division of Mycobacterium tuberculosis takes 14 hours.

If the bacteria enter a favorable environment and have no competitors, the population grows very quickly. Otherwise, its number is regulated by other microorganisms. That is why the human microflora is an essential factor in its protection against various infections.

bacterial spores

One of the features of rod-shaped bacteria is their ability to sporulate. These microorganisms are called bacilli, and they include such pathogenic bacteria:

• The genus Clostridium (cause gas gangrene, botulism, often cause complications during childbirth and after abortion).
• The genus Bacillus (cause anthrax, a number of food poisonings).

Bacterial spores are, in fact, a conserved cell of a microorganism that can survive for a long time without damage, and is practically not subject to various influences. In particular, spores are heat-resistant, not damaged by chemicals. Often the only possible effect is ultraviolet rays, under which the dried bacteria can die.

Bacterial spores form when the microorganism is exposed to unfavorable conditions. It takes approximately 18-20 hours to form inside the cell. At this time, the bacterium loses water, decreases in size, becomes lighter, and a dense shell forms under the outer membrane. In this form, the microorganism can freeze for hundreds of years.

When the spore of a bacterium is exposed to suitable conditions, it begins to germinate into a viable bacterium. The process takes about 4-6 hours.

Types of bacteria

According to the influence of bacteria on humans, they can be divided into three types:

• Pathogenic.
• Conditionally pathogenic.
• Non-pathogenic.

Beneficial bacteria

Non-pathogenic bacteria - those that never lead to disease, even if their numbers are large enough. Among the most known species lactic acid bacteria can be distinguished, which are actively used by humans in the food industry - for the preparation of cheeses, fermented milk products, dough and much more.

Another important species is bifidobacteria, which are the basis of the intestinal flora. In infants on breastfeeding they make up to 90% of all species living in the gastrointestinal tract. These bacteria for humans perform the following functions:

• Provide physiological protection of the intestine from the penetration of pathogenic organisms.
• They produce organic acids that prevent the reproduction of pathogenic microbes.
• They help to synthesize vitamins (K, group B), as well as proteins.
• Enhance the absorption of vitamin D.

The role of bacteria of this species is difficult to overestimate, because without them normal digestion is impossible, and hence the absorption of nutrients.

Opportunistic bacteria

As part of a healthy microflora, there are bacteria that are classified as opportunistic pathogens. These microorganisms can exist for years on the skin, in the nasopharynx or intestines of a person and not cause infections. However, under any favorable conditions (weakened immunity, microflora disturbances), their colony grows and becomes a real threat.

A classic example of an opportunistic bacterium is Staphylococcus aureus, a microbe that can cause over 100 different diseases, from boils on the skin to deadly blood poisoning (sepsis). At the same time, this bacterium is found in most people in various analyzes, but it still does not cause illness.

Among other representatives of the species of opportunistic microbes:

• Streptococci.
• Escherichia coli.
• Helicobacter pylori (capable of causing ulcers and gastritis, but lives in 90% of people as part of a healthy microflora).

Getting rid of these types of bacteria does not make sense, since they are widespread in the environment. The only adequate way to prevent infections is to strengthen the immune system and protect the body from dysbacteriosis.

Pathogenic bacteria behave differently - their presence in the body always means the development of an infection. Even a small colony can cause harm. Most of these microorganisms secrete two types of toxins:

• Endotoxins are poisons that are formed when cells are destroyed.
• Exotoxins are poisons that bacteria produce during their life. The most dangerous substances for humans that can lead to fatal intoxication.

The treatment of such infections is aimed not only at the destruction of pathogenic bacteria, but also at the removal of the poisoning caused by them. Moreover, in the case of infection with microbes such as tetanus bacillus, it is the introduction of toxoid that is the basis of therapy.

Other known pathogenic bacteria include:

• Salmonella.
• Pseudomonas aeruginosa.
• Gonococcus.
• Pale treponema.
• Shigella.
• Tuberculosis bacillus (Koch's stick).

Classes of bacteria

Today there are many classifications of bacteria. Scientists divide them according to the type of structure, ability to move and other features. However, the Gram classification and the type of breathing remain the most important.

Anaerobic and aerobic bacteria

Among the diversity of bacteria, two large classes are distinguished:

• Anaerobic - those that can do without oxygen.
• Aerobic - those that need oxygen to live.

A feature of anaerobic bacteria is their ability to live in environments where other microorganisms do not survive. The most dangerous in this regard are deep contaminated wounds, in which microbes develop rapidly. Characteristic features population growth and life of bacteria in the human body are as follows:

• Progressive tissue necrosis.
• Subcutaneous suppurations.
• Abscesses.
• Internal lesions.

Anaerobes include pathogenic bacteria that cause tetanus, gas gangrene, and toxic lesions of the gastrointestinal tract. Also, the anaerobic class of bacteria includes many opportunistic microbes that live on the skin and in the intestinal tract. They become dangerous if they get into an open wound.

Disease-causing aerobic bacteria include:

• Tuberculosis bacillus.
• Vibrio cholerae.
• Tularemia stick.

The life of bacteria can proceed even with a small amount of oxygen. Such microbes are called facultative aerobic, salmonella and cocci (streptococcus, staphylococcus) are a striking example of the group.

In 1884, Danish physician Hans Gram discovered that different bacteria stained differently when exposed to methylene violet. Some retain color after washing, others lose it. Based on this, the following classes of bacteria were isolated:

• Gram-negative (Gram-) - discoloring.
• Gram-positive (Gram +) - staining.

Staining with aniline dyes is a simple technique that makes it possible to quickly reveal the characteristics of the bacterial membrane wall. For those microbes that do not stain by Gram, it is more powerful and durable, which means that it is more difficult to deal with them. Gram-negative bacteria are primarily more resistant to antibodies produced by the human immune system. This class includes microbes that cause such diseases:

• Syphilis.
• Leptospirosis.
• Chlamydia.
• meningococcal infection.
• Hemophilus infection
• Brucellosis.
• Legionellosis.

The Gram+ class of bacteria includes the following microorganisms:

• Staphylococcus.
• Streptococcus.
• Clostridia (causative agents of botulism and tetanus).
• Listeria.
• Diphtheria stick.

Diagnosis of bacterial infections

Correct and timely diagnosis plays an important role in the treatment of bacterial infections. It is possible to accurately determine the disease only after the analysis, but it can already be suspected by the characteristic symptoms.

Bacteria and viruses: features of bacteria and differences in infections

Most often, a person encounters acute respiratory diseases. Usually cough, rhinitis, elevated temperature and sore throats are caused by bacteria and viruses. And although at certain stages of the disease they can manifest themselves in the same way, their therapy will still be radically different.

Bacteria and viruses behave differently in the human body:

• Bacteria are full-fledged living organisms, large enough (up to 5 microns), capable of reproduction in a suitable environment (on mucous membranes, skin, in wounds). Pathogenic microbes secrete poisons that lead to intoxication. The same bacteria can cause infections of different localization. For example, Staphylococcus aureus affects the skin, mucous membranes, and can lead to blood poisoning.
• Viruses are non-cellular infectious agents that can reproduce only inside a living cell, and in the external environment do not manifest themselves as living organisms. At the same time, viruses are always highly specialized and can only infect a specific type of cell. For example, hepatitis viruses can only infect the liver. Viruses are much smaller than bacteria, their size does not exceed 300 nm.

Today against bacteria developed effective medicines– . But these drugs do not act on viruses, moreover, according to the World Health Organization, antibacterial therapy for ARVI worsens the patient's condition.

Symptoms of bacterial infections

Most often, seasonal respiratory infections develop under the influence of bacteria and viruses according to the following scheme:

• The first 4-5 days appear viral infection.
• On the 4-5th day, if the rules for the treatment of acute respiratory viral infections were not followed, a bacterial lesion joins.

Symptoms of a bacterial infection in this case will be:

• Deterioration of the patient's condition after improvement.
• High temperature (38°C and above).
• Severe pain in chest(a sign of the development of pneumonia).
• Discoloration of mucus - greenish, white or yellowish discharge from the nose and in expectorated sputum.
• Rash on the skin.

If it is possible to treat without the involvement of a doctor, since a viral infection resolves itself without complications in 4-7 days, then diseases caused by pathogenic bacteria must be consulted by a therapist or pediatrician.

Other bacterial infections are characterized by the following symptoms:

• General deterioration.
• A pronounced inflammatory process - pain in the affected area, hyperemia, fever.
• Suppuration.

Methods of transmission of bacterial infections

Harmful bacteria enter the human body in many ways. The most common ways of infection:

• Airborne.

Bacteria are found in the exhaled air, sputum of the patient, spread by coughing, sneezing and even talking. This mode of transmission is typical for respiratory infections, in particular, whooping cough, diphtheria, scarlet fever.

• Contact household.

Microbes get to a person through dishes, door handles, furniture surfaces, towels, phones, toys and more. Also in dust long time contain live bacteria and bacterial spores. This is how tuberculosis, diphtheria, dysentery, diseases caused by aureus and other types of staphylococcus aureus are transmitted.

• Alimentary (fecal-oral).

Bacteria enter the body through contaminated food or water. The transmission route is characteristic of gastrointestinal infections, in particular, typhoid fever, cholera, dysentery.

• Sexual.

Infection occurs during sexual intercourse, this is how STIs are transmitted, including syphilis and gonorrhea.

• Vertical.

The bacterium enters the fetus during pregnancy or childbirth. So the child can become infected with tuberculosis, syphilis, leptospirosis.

Deep wounds are dangerous for the development of infections - it is here that anaerobic bacteria, including tetanus bacillus, actively multiply. People with weakened immune systems are also more likely to contract a bacterial infection.

If you suspect the presence of pathogenic bacteria, the doctor may offer the following diagnostic options:

• Smear on flora.

If a respiratory infection is suspected, it is taken from the mucous membranes of the nose and throat. The analysis is also popular for detecting sexually transmitted infections. In this case, the material is taken from the vagina, visceral canal, urethra.

• Bacteriological culture.

It differs from a smear in that the taken biomaterial is not examined immediately, but is placed in an environment favorable for the reproduction of bacteria. After a few days or weeks, depending on the alleged pathogen, the result is evaluated - if there were harmful bacteria in the biomaterial, they grow into a colony. Bakposev is also good because during the analysis, not only the pathogen is determined, but also its quantity, as well as the sensitivity of the microbe to antibiotics.

• Blood analysis.

A bacterial infection can be detected by the presence of antibodies, antigens in the blood and by the leukocyte formula.

Today, the biomaterial is often studied PCR method(polymerase chain reaction), at which infection can be detected even with a small number of microbes.

Positive test and bacterial infections

Since many bacteria are opportunistic and at the same time live in the body, on the mucous membranes and skin of the majority of the population, the results of the analysis must be able to correctly interpret. It must be remembered that the mere presence of bacteria in a person is not a sign of a bacterial infection and is not a reason to start treatment. For example, the norm for Staphylococcus aureus is 103–104. With these indicators, no therapy is required. Moreover, since the microflora of each person is individual, even if the values ​​\u200b\u200bare higher, but there will be no symptoms of the disease, the indicators can also be considered normal.

An analysis for different types of bacteria is prescribed if there are signs of infection:

• Bad feeling.
• Purulent discharge.
• Inflammatory process.
• Greenish, white or yellow mucus from the nose and in the expectorated sputum.

A positive analysis for bacteria in the absence of symptoms is taken for control if microbes are detected in people from risk groups: pregnant women, children, people in the postoperative period, patients with reduced immunity and concomitant diseases. In this case, it is recommended to take several tests to see the growth dynamics of the colony. If the values ​​do not change, then the immune system is able to control the reproduction of bacteria.

Bacteria in the nasopharynx

Bacteria in the nasopharynx can cause respiratory tract infections. In particular, they are the cause of tonsillitis, bacterial tonsillitis and pharyngitis, as well as sinusitis. Advanced infections can cause many inconveniences, chronic inflammatory processes, persistent rhinitis, headaches and more. Such diseases are especially dangerous because harmful bacteria can descend through the respiratory tract and affect the lungs - causing pneumonia.

bacteria in urine

Ideally, it is urine that should be free from various microorganisms. The presence of bacteria in the urine may indicate an incorrectly passed analysis (in which microbes got into the material from the surface of the skin and mucous membranes), in which case the doctor asks to be examined again. If the result is confirmed, and the indicator exceeds 104 CFU / ml, bacteriuria (bacteria in the urine) indicates such diseases:

• Kidney damage, in particular, pyelonephritis.
• Cystitis.
• Urethritis.
• Inflammatory process in the urinary canal, for example, as a result of blocking it with a calculus. Observed in urolithiasis.
• Prostatitis or prostate adenoma.

In some cases, bacteria in the urine are found in diseases that are not associated with a local infection. A positive test may be diabetes, as well as a generalized lesion - sepsis.

Normally, the gastrointestinal tract is inhabited by colonies of various bacteria. In particular, there are:

• Bifidobacteria.
• Lactic acid bacteria (lactobacilli).
• Enterococci.
• Clostridia.
• Streptococci.
• Staphylococci.
• Escherichia coli.

The role of bacteria that make up normal microflora, - protection of the intestines from infections and ensuring normal digestion. Therefore, often the biomaterial from the intestine is examined precisely because of the suspicion of dysbacteriosis, and not for the presence of pathogenic microorganisms.

However, some pathogenic bacteria can cause serious illnesses, precisely when it enters the gastrointestinal tract. Among these diseases:

• Salmonellosis.
• Cholera.
• Botulism.
• Dysentery.

bacteria on the skin

On the skin, as well as on the mucous membranes of the nasopharynx, in the intestines and genital organs, the balance of microflora is normally established. Bacteria live here - more than 100 species, among which epidermal and Staphylococcus aureus, streptococci are often found. With reduced immunity, and especially in children, they can provoke skin lesions, cause suppuration, boils and carbuncles, streptoderma, panaritium and other diseases.

AT adolescence active reproduction of bacteria leads to acne and acne.

The main danger of microbes on the skin is the possibility of their entry into the bloodstream, wounds and other damage to the epidermis. In this case, harmless microorganisms on the skin can cause serious illness, even cause sepsis.

Diseases caused by bacteria

Bacteria are the cause of infections throughout the body. They strike Airways, cause inflammatory processes on the skin, cause diseases of the intestines and the genitourinary system.

Diseases of the respiratory tract and lungs

Angina

Angina is an acute lesion of the tonsils. The disease is typical for childhood.

Pathogen:

• Streptococci, rarely staphylococci and other forms of bacteria.

Typical symptoms:

• inflammation of the tonsils with a whitish coating on them, pain when swallowing, hoarseness, heat, no rhinitis.

Disease risk:

• if a sore throat is not treated well enough, rheumatoid heart disease can become a complication - harmful bacteria spread through the blood and lead to heart valve defects. As a result, heart failure may develop.

whooping cough is dangerous infection that mainly affects children. Highly contagious, the bacterium is transmitted by airborne droplets, therefore, without a sufficient level of immunization of the population, epidemics are easily caused.

Pathogen:

• Bordetella pertussis.

Typical symptoms:

• the disease at first proceeds like a common cold, later a characteristic paroxysmal barking cough appears, which may not go away for 2 months, after an attack the child may vomit.

Disease risk:

• Whooping cough is most dangerous for children of the first year of life, as it can cause respiratory arrest and death. Typical complications are pneumonia, bronchitis, false croup. From severe coughing attacks, it is extremely rare for a cerebral hemorrhage or pneumothorax to occur.

Pneumonia

Inflammation of the lungs can be caused by bacteria and viruses, as well as some fungi. Bacterial pneumonia, the most common complication of viral respiratory infections, can develop after the flu. Also, the multiplication of bacteria in the lungs is typical for bedridden patients, the elderly, patients with chronic diseases lungs and respiratory disorders, with dehydration.

Pathogen:

• Staphylococci, pneumococci, Pseudomonas aeruginosa and others.

Typical symptoms:

• severe fever (up to 39 ° C and above), cough with copious moist greenish or yellowish sputum, chest pain, shortness of breath, feeling short of breath.

Disease risk:

• depends on the pathogen. With insufficient treatment, respiratory arrest and death are possible.

Tuberculosis

Tuberculosis is one of the most dangerous lung diseases that is difficult to treat. Since 2004, tuberculosis has been a social problem in Russia. significant illness, since the number of infected is much higher than in developed countries. Back in 2013, up to 54 cases of infection per 100,000 people were recorded.

Pathogen:

• mycobacterium, Koch's bacillus.

Typical symptoms:

• the disease may not manifest itself for a long time, then a cough occurs, a general malaise, a person loses weight, subfebrile temperature(37-38°C) for a month or more, painful blush. Later, hemoptysis and severe pain appear.

Disease risk:

• features of the bacteria that cause tuberculosis is the development of resistance to antibiotics. Therefore, the infection is difficult to treat and can lead to death or disability. Frequent complications- heart disease.

Diphtheria is an infectious disease that in 90% of cases affects the upper respiratory tract. Diphtheria is especially dangerous for young children.

Pathogen:

• Corynebacterium diphtheriae (Leffler's bacillus).

Typical symptoms:

• pain when swallowing, hyperemia of the tonsils and specific white films on them, swollen lymph nodes, shortness of breath, high fever, general intoxication of the body.

Disease risk:

• without timely treatment diphtheria is fatal. The bacterial cell is capable of producing exotoxin, so the sick person can die from poisoning, in which the heart and nervous system are affected.

Intestinal infections

salmonellosis

Salmonellosis is one of the most common intestinal infections that can occur in different forms. Sometimes bacteria cause severe lesions, but there are cases when the disease resolves in mild form or no symptoms at all.

Pathogen:

• Salmonella.

Typical symptoms:

• high temperature (up to 38-39 ° C), chills, abdominal pain, vomiting, diarrhea, severe intoxication of the body, in which a person sharply weakens.

Disease risk:

• Depends on the form of the course, in severe infections, bacterial toxins can lead to kidney failure or peritonitis. Children are at risk of dehydration.

Dysentery

Dysentery is an intestinal infection that affects people of all ages. Most often recorded in the summer hot period.

Pathogen:

• 4 types of Shigella bacteria.

Typical symptoms:

• Loose stools of dark green color with impurities of blood and pus, nausea, headaches, loss of appetite.

Disease risk:

• dehydration, which leads to the attachment of various inflammations, as well as intoxication of the body. At proper treatment, good immunity and sufficient fluid intake, the life of Shigella bacteria stops in 7-10 days. Otherwise, a serious complication is possible - intestinal perforation.

Gonorrhea

Gonorrhea is transmitted exclusively through sexual contact, but in rare cases, the infection can be passed from mother to child during childbirth (the baby develops conjunctivitis). The bacteria that causes gonorrhea can grow in the anus or throat, but it most often affects the genitals.

Pathogen:

• Gonococcus.

Typical symptoms:

• possible asymptomatic course of the disease: in men in 20%, in women - more than 50%. At acute form there are pains when urinating, white-yellow discharge from the penis and vagina, burning and itching.

Disease risk:

• if the infection is not treated, it can cause infertility, as well as lead to damage to the skin, joints, of cardio-vascular system, liver and brain.

Syphilis

Syphilis is characterized by slow progression, symptoms appear gradually and do not develop quickly. The characteristic course of the disease is an alternation of exacerbations and remissions. Household infection, many doctors question, in the vast majority of cases, bacteria are transmitted to humans sexually.

Pathogen:

• Pale treponema.

Typical symptoms:

• at the first stage, an ulcer appears on the genitals, which heals on its own in 1-1.5 months, an increase in lymph nodes is observed. After, after 1-3 months, a pale rash appears all over the body, the patient feels weak, the temperature may rise, the symptoms resemble the flu.

Disease risk:

• pathogenic bacteria eventually lead to the development of tertiary syphilis (30% of all infected), which affects the aorta, brain and back, brain, bones and muscles. Possibility of developing a lesion nervous system- neurosyphilis.

Chlamydia

Chlamydia is a sexually transmitted infection that is often asymptomatic. In addition, pathogenic bacteria are difficult to detect; PCR analysis is prescribed for diagnosis.

Pathogen:

• Chlamydia.

Typical symptoms:

• in the acute form, discharge from the genital organs (usually transparent), pain during urination, blood discharge are observed.

Disease risk:

• in men - inflammation of the epididymis, in women - inflammation of the uterus and appendages, infertility, Reiter's syndrome (inflammation of the urethra).

Meningococcal infection

Meningococcal disease is a group of diseases caused by one pathogen, but occurring in different form. A person may be an asymptomatic carrier of the bacterium, and in other cases, the microbe causes a generalized infection leading to death.

Pathogen:

• Meningococcus.

Typical symptoms:

• vary with the severity of the disease. The infection can manifest itself as a mild cold, in severe cases, meningococcemia develops, characterized by an acute onset of the disease, the appearance of a red rash (does not disappear with pressure), the temperature rises, confusion is observed.

Disease risk:

• in severe form, tissue necrosis develops, gangrene of the fingers and extremities, and brain damage are possible. With the development of infectious-toxic shock, death quickly occurs.

Tetanus

Tetanus is a dangerous infection that develops in wounds on the skin. The causative agent forms spores of bacteria, in the form of which it is found in the external environment. When it enters the wound, it quickly germinates. Therefore, any serious injury requires the prevention of infection - the introduction of tetanus toxoid.

Pathogen:

• Tetanus stick.

Typical symptoms:

• tetanus affects the central nervous system, at first it is manifested by tonic tension of the jaw muscles (it is difficult for a person to speak, open his mouth), later it spreads to the whole body, the patient arches due to muscle hypertonicity, and at the end respiratory failure develops.

Disease risk:

• the main danger is the toxin that the bacterium secretes, it is he who leads to severe symptoms. As a result of poisoning, tonic tension of all muscles occurs, including the diaphragm and intercostal muscles, as a result of which a person cannot breathe and dies from hypoxia.

Treatment of bacterial diseases

Any bacterial infection needs planned treatment, because bacteria can cause serious damage to the body. Only the doctor chooses the appropriate treatment regimen, which depends not only on the type of disease, but also on the severity of the course.

Antibiotics

Antibiotics are considered the mainstay of treatment for all infections caused by harmful bacteria. Since the discovery of penicillin in the 1920s, many diseases have been moved from fatal to curable. The number of complications after operations has decreased, and, from which every fourth person died, remained a dangerous disease only for people from risk groups.

Modern antibiotics can be divided into two groups:

• Bactericidal - kill pathogenic bacteria.
• Bacteriostatic - slow down the growth, stop the reproduction of bacteria.

The former have a more pronounced effect, however, it is the drugs from the second group that are prescribed more often, since, as a rule, they cause fewer complications.

It is also customary to divide drugs according to the spectrum of action:

• Broad-spectrum antibiotics (penicillins, tetracyclines, macrolides) are used to destroy different types bacteria. They are effective in the case when treatment needs to be started urgently, even before the tests. Penicillins are most commonly prescribed for respiratory bacterial infections.
• Antibiotics that are active against a limited number of bacterial species (often prescribed for tuberculosis and other specific infections).

Any antibiotics must be taken in a course, because if treatment is interrupted, the remaining living bacteria quickly restore the colony.

Problems in the use of antibiotics

Despite the widespread use of antibiotics, doctors today are looking for alternative drugs to treat bacterial infections. It is associated with several significant shortcomings these medicines:

• Development of resistance in bacteria.

Many microorganisms have developed defense mechanisms against drugs, and the use of classical antibiotics is no longer effective. For example, first-generation penicillins, which actively fought against staphylococci and streptococci, are not used today. Staphylococcus aureus learned to synthesize the enzyme penicillinase, which destroys the antibiotic. Of particular danger are new strains of bacteria that have developed resistance to drugs. latest generations the so-called superbugs. The most famous of these is methicillin-resistant Staphylococcus aureus. Also, Pseudomonas aeruginosa and enterococci quickly develop resistance.

• The use of broad-spectrum antibiotics leads to dysbacteriosis.

After such treatment, the balance of microflora is significantly disturbed, complications often develop, the body is weakened not only by the disease, but also by the action of drugs. The use of medicines is limited among certain population groups: pregnant women, children, patients with liver and kidney damage, and other categories.

bacteriophages

An alternative to antibiotics could be bacteriophages, viruses that kill a specific class of bacteria. Among the advantages of such drugs:

• Low likelihood of developing resistance, since bacteriophages are organisms that have lived on Earth for several billion years and continue to infect bacterial cells.
• They do not violate the microflora, since they are specialized medicines - effective only in relation to a specific type of microorganisms.
• Can be used by people at risk.

Preparations containing bacteriophages are already available in pharmacies today. But still, such therapy is losing to antibiotics. Many diseases require immediate treatment, which means that broad-spectrum drugs are needed, while bacteriophages are highly specialized - they can be prescribed only after the pathogen has been identified. In addition, currently known viruses are not able to destroy such a large list of pathogenic bacteria as antibiotics.

Other treatments

WHO does not recommend the use of antibiotics for all types of bacterial infections. In the event that the microbe does not have a high pathogenicity, and the disease proceeds without complications, symptomatic treatment is sufficient - the use of antipyretics, painkillers, vitamin complexes, heavy drinking and other things. Often the immune system itself can suppress the reproduction of a colony of pathogenic microorganisms. However, in this case, the patient must be under the supervision of a doctor who will decide on the appropriateness of a particular method of therapy.

Effective vaccines have been developed for many deadly bacterial infections. Vaccinations are recommended for the following diseases:

• Tuberculosis.
• Haemophilus infection.
• Pneumococcal infection.
• Diphtheria (toxoid is used - a vaccine that helps produce antibodies to the toxin of the bacterium).
• Tetanus (toxoid is used).

Bacteria, nutrition and digestion

The live bacteria in foods alone can restore the gut microflora, help the digestive tract, and get rid of toxins. Others, on the contrary, getting into the digestive tract with food, cause dangerous infections and serious poisoning.

• Pathogenic bacteria often multiply in products with violations of storage rules. And breeding anaerobic bacteria are especially dangerous here, which easily increase their numbers even in goods in sealed packaging and canned food.
• Another way of food contamination is through unwashed hands or equipment (knives, cutting boards, etc.). Therefore, food poisoning is easy to get after street food, which was prepared without observing sanitary standards.
• Insufficient heat treatment or its absence also increases the likelihood of the reproduction of various pathogenic forms of bacteria.

Medicines with live bacteria

Preparations with beneficial live bacteria are often recommended by nutritionists for various disorders of the gastrointestinal tract. They help with bloating, flatulence, heaviness, poor digestion of food, frequent poisoning.

In the event that dysbacteriosis is severe, the doctor may recommend a course of drugs to restore microflora.

• Probiotics are products that contain live beneficial bacteria.

The drug is available in capsules with a shell that protects the colonies of microorganisms and helps to deliver them to the intestines in a living form.

• Prebiotics are carbohydrate preparations that contain nutrients for beneficial bacteria.

Such drugs are prescribed if the intestines are inhabited by bifidus and lactobacilli, but their colonies are not large enough.

Lactic acid bacteria are an extensive group of microorganisms that are able to process glucose with the release of lactic acid. In fact, this means that it is precisely these microbes that are involved in the process of fermenting milk - with their help, all dairy products. Food does not spoil longer precisely thanks to lactic acid bacteria - the acidic environment that they create prevents the growth of pathogens. They exhibit the same protective functions in the human intestine.

The main products in which lactic acid bacteria are present:

• Yogurt without additives.
• Starter cultures, kefir and other fermented milk drinks.
• acidophilus milk.
• Hard cheeses.
• Sauerkraut.

Tables of the main bacteria

Pathogenic bacteria

Bacteria in the table are presented by the main types of microbes that can cause disease. However, many of them also include non-pathogenic or opportunistic bacteria.

Beneficial bacteria

The table of bacteria represents the types of microbes that are vital to humans.

A person often treats his body relatively lightly. Yes, many people know where the heart, kidneys, intestines, etc. are located. Some have a deeper knowledge of the structure human body. But few people dare to look at themselves not only as a person, but as a biological mechanism that works according to certain laws and lives its own complex and multidimensional biological life. So, for example, not everyone clearly understands how valuable our biological cohabitation with protozoa is and how terrible the bacterial threat is.

Bacteria without which a person cannot survive

The human body is inhabited by a huge number of bacteria, without which a person cannot survive. The total weight is from 1.5 to 2.5 kg. Such a useful stable symbiosis was formed:

• in the gastrointestinal tract;
• on the skin;
• in the nasopharynx and oral cavity.

The main principle of the work of bacteria in the body is the creation of such an environment on the tissues of organs in which harmful microbes cannot survive. Accordingly, getting on the skin, in the nasopharynx or in the gastrointestinal tract, pathogenic microbes simply die, since the environment already formed by beneficial microbes on the tissues of these organs is fatal for virulent (dangerous) prokaryotes.

This is a general picture of the influence of beneficial bacteria, while the local effect of microbes has features depending on the organ in which such a symbiotic interaction occurs.

Gastrointestinal tract

The bacteria that inhabit the human gastrointestinal tract perform several functions at once, thanks to which a person has the opportunity to survive as a biological organism:

1. Microbes create an antagonistic environment for pathogenic microbes in the intestine. This role of beneficial microorganisms boils down to the fact that they create an acidic environment in the intestines, and pathogenic microbes do not live well in an acidic environment.
2. The same beneficial bacteria digest plant foods that enter the intestines. Enzymes synthesized by the human body are not able to digest plant cells containing cellulose, and bacteria feed on such cells freely, thus playing another important role.
3. Also, beneficial bacteria synthesize vitamins of groups B and K that are necessary for a person. The role of vitamins of group K is to ensure metabolism in bones and connective tissues. The role of B vitamins is global. These low molecular weight organic compounds are involved in a huge number of processes, from the release of energy from carbohydrates to the synthesis of antibodies and the regulation of the nervous system. Despite the fact that B vitamins are present in many foods, it is thanks to their synthesis by the intestinal microflora that the body receives the amount of these vitamins that is necessary for normal human life.

The main part of useful intestinal microflora- lactic acid bacteria. Despite the fact that these bacteria may have different names, they have the same type of effect on the body. Lactic acid bacteria ferment natural sugars, resulting in the formation of a product such as lactic acid.

The most popular lactic acid microorganisms today are those that are advertised as the main probiotic agent in the composition of healthy products.

• bifidobacteria- filamentous lactic acid microorganisms that cover the surface of the intestine and prevent harmful microbes from gaining a foothold and multiplying on its walls. The total weight of lactic acid bifidobacteria in relation to other symbiont bacteria is about 80%.
• lactobacilli- gram-positive lactic acid rods, the main role of which is not only the digestion of plant foods and the creation of an antagonistic environment, but also the stimulation of antibody synthesis. These are microorganisms that have a huge impact on the human immune system.

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In addition to useful lactic acid prokaryotes, there are conditionally harmful ones in the gastrointestinal tract -. Despite the fact that they can also have a beneficial effect, for example, the bacteria of the Escherichia coli group also synthesize vitamins of the K group, with an increase in their number in the gastrointestinal tract, the effect becomes harmful: E. coli poison the body with toxins.

The total weight of E. coli that are present in the human body is very small compared to two kilograms of beneficial microorganisms.

Bacteria on the skin, in the mouth and in the nasopharynx

Microorganisms that inhabit skin human, play the role of a natural biological shield, they also do not allow harmful bacteria develop active activity on the skin and thereby have a toxic effect on the entire body.

The main bacteria that control the safety of the skin, mouth and nasopharynx are:

• micrococci;
• streptococci;
• staphylococci.

Streptococci and staphylococci have harmful (pathogenic) representatives in their genus that can poison the body.

Causes of diseases

A logical question arises: if a person is protected from all sides by a biological shield, then why do people still get sick, why does this shield not work?

The body's resistance to pathogenic agents largely depends on the immune system. Therefore, it is important how much work is done to ensure that the immune system is sufficiently active.

The second important circumstance is the characteristics of the most harmful agent and how it affects the body.

So, for a long time, typhus was a deadly threat to humans.

Typhus is the collective name for several deadly diseases that have claimed many lives until cures were found.

Common features characteristic of all types of typhus:

• a person quickly loses weight;
• against the background of intoxication and weight loss, a severe fever begins;
• all of these painful manifestations cause the strongest nervous breakdown and the person dies.

In spite of general symptoms The causes of typhus are different each time.

Disease causing bacteria

In the intestines of lice, a large number of rickettsiae. However, the likelihood of infection does not depend on how many lice are in close proximity to a person, but on how actively a person begins to fight lice. Scratching lice on oneself is the main cause of infection with typhus. It is from the crushed intestines of the louse that the rickettsia enter the wounds on the skin and further into the human bloodstream.

Main symptoms typhus:

• fever (body temperature above 40ºС);
• backache;
• pink rash in the abdomen;
• the patient's consciousness is inhibited almost to the point of coma.

The treatment of typhus, like the treatment of any bacterial infection, is based on antibiotics. Antibiotics of the tetracycline group are used to treat this type of typhoid.

Another terrible type of typhus - returnable. It is carried by ticks and lice. But it is the spirochete Borrelia bacteria that are the causative agents. Infection occurs during a tick bite.

The main symptoms of infection:

• vomit;
• the spleen and liver are enlarged;
• starts mental disorder and hallucinations.

The same symptoms occur if the carriers were lice.

Treatment - antibiotics of the penicillin and chloramphenicol groups, as well as arsenic preparations.

Typhoid fever. The causative agent is a pathogenic bacterial bacillus from the genus Salmonella. This type of typhoid is dangerous only for humans, animals do not get sick with typhoid fever. Pathogens enter the stomach with food. Main symptoms:

• the appearance of bacteria in the urine (bacteremia);
• general symptoms of intoxication (pallor, headache, heart rhythm disorder);
• bloated belly;
• delusions, hallucinations and other mental disorders.

Treatment is also carried out with antibiotics of chloramphenicol and penicillin groups and is accompanied by general strengthening therapy.

In addition to typhoid pathogens, a person is threatened by a host of other pathogenic microbes, the timely detection of which, as well as the identification of infection symptoms, its identification and treatment, can cost a person life.

The same plague is a disease with a high lethality, the cause of which is a plague bacillus. Symptoms are weight loss, fever and dehydration. A person dies from dehydration.

The carriers of the plague bacillus can be rodents, pets, insects.

Plague is treated with antibiotics of the streptomycin group. An important role is played by prevention and general strengthening of the body.