Microorganisms are ubiquitous in the environment. They are found in soil, water, air, humans and animals. Microorganisms are involved in the processes of transformation of substances, their assimilation by plants and animals.

Microorganisms have the ability to adapt (adapt) to the most different conditions environment. They are found in a variety of combinations (associations) and quantities. Each object has its own characteristic microflora. Our knowledge of the characteristics of the spread of microorganisms helps to prevent infectious diseases and even eliminate some of them.

Soil microflora

In the soil, microorganisms find the most favorable conditions for their development. Organic substances, mineral compounds, sufficient soil moisture create conditions for the accumulation of a huge number of microorganisms in it.

The richest in microorganisms is the cultivated, cultivated soil (up to 5 billion in 1 g of soil), the least is the soil of deserts, poor in moisture and organic matter (200 million in 1 g).

The number of microorganisms in the soil in different climatic conditions: in the southern regions it is much higher. Their distribution is uneven in different soil layers. So, in the surface layer of the soil, due to the destructive effect of sunlight and drying, microorganisms are relatively few, at a depth of 10-20 cm their number reaches a maximum and then, as it deepens, their number rapidly decreases.

The microflora of the soil is very diverse; it consists of nitrifying, nitrogen-fixing, denitrifying, cellulose-decomposing bacteria; sulfur and iron bacteria, fungi, algae, protozoa. Most of the microorganisms that live in the soil take part in the cycle of substances in nature: the decomposition of organic substances to inorganic ones, the assimilation of mineral elements and the fixation of atmospheric nitrogen by plants. With the help of microorganisms, the structure changes and chemical composition soil.

The soil can serve as a transmission path for infectious agents. Pathogenic bacteria enter the soil with human and animal excreta, corpses and wastes. Most of them, due to a lack of nutrients, the influence of sunlight and the action of antagonistic microbes, quickly die. However, some microorganisms persist long enough for the infection to spread (from several hours to several months). There are also microorganisms that persist for a long time (for many years) in the soil, through which animals and humans are infected. These include spore-forming bacteria: the causative agents of anthrax, tetanus, gas gangrene. And, finally, for some microorganisms, the soil is a permanent habitat: causative agents of botulism, actinomycetes, etc.

Microflora of water

Open water is a natural habitat for many microorganisms. They enter the water from the soil, with human and animal excreta, waste, sewage.

The usual microflora of the soil is saprophytes. The water is inhabited by pseudomonads, micrococci, vibrios. In addition, pathogens of infectious diseases can get into the water, persist and even multiply. For example, E. coli and typhoid fever pathogens survive in water for a long time, and cholera pathogens multiply.

The intensity of the seeding of water by microorganisms and the composition of microflora depend on the degree of pollution of the reservoir, especially organic compounds... In the vicinity of populated areas, in which reservoirs are polluted with sewage, industrial and industrial waters, the number of microorganisms in the water is especially high, and the microflora is more diverse.

Self-purification processes constantly take place in the water - microorganisms die from the action of sunlight and chemical substances, sedimentation, exposure to antibiotic substances produced by other microorganisms, algae, fungi.

The water of the seas and oceans is also rich in microorganisms, but there are much less of them than in freshwater open bodies of water. There are especially many microorganisms in the bottom silt layer, on which they form a thin film. The cleanest are soil waters that come to the surface through artesian wells and springs.

Water plays an important role in the transmission of infectious diseases. The causative agents of intestinal infections, poliomyelitis, tularemia, leptospirosis often cause "water" epidemics, and for cholera, water is the main route of transmission.

Determining the purity of water and preventing its pollution is one of the mandatory measures in the fight against infectious diseases.

Microflora of air

The air does not contain nutrient substrates necessary for the development of microorganisms. In addition, solar radiation, temperature changes and other factors have an adverse effect on microorganisms. Despite this, a significant number of microorganisms are constantly in the air, which enter the air with dust from the soil surface. The most common spores of fungi and bacteria, pigment saprophytic bacteria, mold and yeast fungi, and various cocci are found in the air.

The number of microorganisms in the air varies widely.

The air is most polluted in large industrial cities. V countryside the air is much cleaner, and the least microorganisms are found in the air above the forest, mountains, seas.

There are fewer microorganisms in the upper layers of the atmosphere than in the lower ones; less in winter than in summer; more indoors than outdoors. There are especially many bacteria in poorly ventilated rooms in the absence of wet cleaning.

Pathogenic microorganisms enter the air along with droplets of saliva and phlegm, when coughing, sneezing, talking of sick people, as well as dust from contaminated objects and infected soil.

Microorganisms are in the air in the form of an aerosol (droplets of liquid or in the smallest solid particles suspended in the air).

Breathing in air contaminated with pathogenic microorganisms can make a person sick. This route of transmission is called airborne (airborne dust).

Low-resistant pathogenic microorganisms are usually transmitted only at a distance close to the patient (the causative agent of measles, influenza, whooping cough); dust particles carry cocci, spores and more resistant microorganisms. The latter include the causative agents of anthrax, tuberculosis, etc. Epidemics of diseases spreading through the air usually occur in winter when people are crowded in closed rooms, insufficiently ventilated and in the absence of daily wet cleaning.

To prevent these diseases, gauze masks are used, which are used by medical personnel, patients, employees of children's institutions.

Microflora of the human body

Normal human microflora has developed as a result of the interaction of micro- and macroorganisms in the process of evolution. A set of microbial species characteristic of individual organs and cavities of the body - biocenosis - necessary condition normal life of the body. Violation of the biocenosis, the appearance of microorganisms unusual for it, especially pathogens, causes the development of the disease.

The human fetus is sterile during pregnancy. Already during childbirth, microorganisms enter the child's body from the mother's birth canal. They also come from the mother's skin, the hands of staff, the environment and the air.

During a person's life, the nature of the microflora changes, but in general it is constant and characteristic of individual organs. Internal organs humans are usually sterile (blood, brain, liver, etc.). Organs and tissues that communicate with the environment contain microorganisms.

Skin microflora pretty constant. It is represented by staphylococci, streptococci, diphtheroids, spore-forming bacteria, yeast-like fungi. The nutrient substrate for them is the secretion of the sebaceous and sweat glands, dead cells and decay products. Microorganisms caught on clean healthy skin usually die from the effects of secretions from various glands and bacteria that constantly inhabit the skin.

Skin pollution contributes to the development of pathogenic microorganisms, therefore it is very important to keep the skin clean at all times.

Oral microflora abundant and varied. Constant temperature, humidity, availability of nutrients, alkaline reaction of saliva create favorable conditions for the development of microorganisms. Various types of cocci, lactic acid bacteria, diphtheroids, spirochetes prevail; there are spindle-shaped rods, actinomycetes and yeast-like fungi.

Oral microorganisms play an important role in the development of dental caries, stomatitis, and inflammation of soft tissues. In the first stage of the inflammatory process, streptococci, bacteroids, actinomycetes predominate. As caries develops, putrefactive bacteria join them: Proteus, Clostridia, etc. In the prevention of these diseases, oral hygiene is of great importance.

Microflora of the gastrointestinal tract... Usually the microflora of the stomach is extremely scarce due to the destructive effect of acidic gastric juice. In the small intestine, despite the alkaline reaction, there are also few microorganisms due to the unfavorable action of enzymes. In the large intestine, conditions for the reproduction of microorganisms are more favorable. Throughout a person's life, the microflora of the large intestine changes: in infants, lactic acid bacteria predominate, in adults, usually bacteroids, bifidobacteria, Escherichia coli, fecal streptococcus, etc. are found. About a third of feces are various microorganisms.

Microflora of the respiratory tract... Man inhales with air great amount microorganisms. However, most of them are retained in the nasal cavity or are excreted through the ciliated epithelium of the upper respiratory tract. In the nasopharynx and pharynx, staphylococci, streptococci, diphtheroids, etc. are usually found.When the body is weakened (cooling, exhaustion, injury), microorganisms - permanent inhabitants of the upper respiratory tract - can cause various diseases, affecting the lower parts of the respiratory tract (bronchitis, pneumonia ).

Microflora of the mucous membrane of the eyes very scarce due to the action of the lysozyme contained in tears on it. Nevertheless, staphylococci and diphtheroids are found on the conjunctiva.

Vaginal microflora changes over the course of a woman's life. In girls, the coccal flora predominates, in adult women, Dederlein's bacillus.

The normal microflora of a person is a necessary condition for maintaining his health. Violation of microbial biocenoses in different organs and systems of the body leads to the development of pathological processes, a decrease in the body's defenses, and the development of dysbiosis.

Control questions

1. What is the characteristic of the microflora of soil, water, air?

2. What is the role of the normal microflora of the human body?

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The microflora of the air depends on the microflora of the water and soil, above which the layers of air are located. In soil and water, microbes can multiply; in the air, they do not multiply, but only remain for some time. Raised into the air with dust, they either settle with drops back to the surface of the earth, or die in the air from lack of nutrition and from the action of ultraviolet rays. However, some of them are more resistant, for example, tubercle bacillus, spores of clostridia, fungi, etc., can persist in the air for a long time.

Nai large quantity microbes are found in the air of industrial cities. The cleanest air is over forests, mountains, snowy expanses. The upper layers of the air contain fewer germs. Above Moscow, at an altitude of 500 m, one meter of air contains 2-3 bacteria, at an altitude of 1000 m - 2 times less. The air in closed rooms is very rich in microbes, especially in medical and prophylactic institutions, kindergartens, schools, etc. Along with harmless saprophytes, pathogenic microbes are often found in the air.

When coughing, sneezing, tiny aerosol droplets containing pathogens such as influenza, measles, whooping cough, tuberculosis and a number of others, transmitted by airborne droplets from a sick person to a healthy person, are thrown into the air, causing the disease.

Sanitary and bacteriological examination of air

The accumulation and circulation of pathogens in the air of medical institutions is one of the reasons for the emergence of hospital purulent-septic infections, which cause colossal economic damage, increasing the cost of treatment by 2 times.

As a result, in recent years, much attention has been paid to the sanitary-bacteriological study of air in hospitals, operating rooms, maternity hospitals, children's institutions, etc. Research is carried out both in a planned manner and according to epidemiological indications. A bacteriological study of the air includes:

Determination of the total content of microbes in 1 m3 of air;

Determination of the content of Staphylococcus aureus in 1 m3 of air.

Air sampling for bacterial research is carried out in the following rooms:

* operating units;

* dressings;

“Recovery wards; “Delivery rooms;

* wards for newborns;

* wards for premature babies;

* postpartum wards;

* departments and wards of intensive care and other premises requiring aseptic conditions.

Air sampling methods

There are two main ways to take air samples for research:

1. sedimentation - based on the mechanical sedimentation of microorganisms;

2. aspiration - based on active air suction (this method makes it possible to determine not only the qualitative, but also the quantitative content of bacteria).

Air samples are taken by the aspiration method using the Krotov apparatus, which consists of three main parts: base, body and cover. A disc made of transparent organic glass with a wedge-shaped slot for air suction is fixed in the lid. To determine the amount of air that has passed through the device, a rotameter is placed on the outer wall of the housing. In the upper part of the body there is a rotating disc on which the Petri dish is installed. Air is drawn into the device centrifugal fan mounted on the axis of the electric motor. The air stream entering the device hits the surface of the nutrient medium in the cup, leaving microorganisms on it, and, flowing around the electric motor, comes out through the rotameter.

The air pulling speed is 25 liters per minute. The amount of air passed through should be 100 liters for the total bacteria count and 250 liters for the presence of Staphylococcus aureus.

When taking samples in different rooms, it is necessary to treat the surface of the apparatus, the table, the inner walls with a disinfectant solution of 70 ° alcohol.

Determination of the microbial number, pathogenic microorganisms

To determine the total content of bacteria in 1 m3 of air, samples are taken on 2% nutrient agar. The inoculations are incubated at 37 ° C for 24 hours, then left for 24 hours at room temperature, the number of grown colonies is counted and recalculated per 1 m3 of air. If mold colonies have grown on nutrient agar plates, they are counted and recalculated per 1 m3 of air. In the protocol, the number of molds is indicated separately.

Payment. For example, 125 liters of air were passed in 10 minutes, and 100 colonies grew on the surface.

100x1000 l The number of microbes in 1 m3 of air = - T - = 800 l, i.e.

The number of grown colonies -1000 l the amount of passed air

To determine the presence of Staphylococcus aureus, samples are taken on yolk-salt agar (YSA). The cups are placed in a thermostat at 37 ° C for 24 hours and kept for another 24 hours at room temperature, or 48 hours at 37 ° C. Colonies suspected of staphylococcus aureus are subject to mandatory microscopy and further identification.

First of all, colonies of staphylococci are removed from yolk-salt agar, which form a rainbow corolla around the colony (positive lecitovitellase reaction). Pigmented colonies with a negative lecitovitellase reaction of at least two colonies of different types are also subjected to further study. Suspect colonies are subcultured on blood or milk agar plates. Further study of them is carried out according to the scheme.

Bacteriological examination for staphylococcus

Sowing on elective media (yolk-saline, mole-saline or milk-yolk-saline agar). The seeded media are kept in a thermostat at 37 ° C for 2 days, or one day in a thermostat and an additional 24 hours in the light at room temperature.

2-3rd day.

Viewing the cups, fixing the character and massiveness of growth in the journal. On the above media, staphylococcus aureus grows in the form of round, shiny, masticatory, convex pigmented colonies. On media containing yolk, Staphylococcus aureus, isolated from humans, in 60-70% of cases forms a rainbow corolla around the colony (positive lecitovitellase reaction).

Graft onto agar slant for further investigation of at least 2 colonies suspected of staphylococcus aureus. For research, first of all, colonies that give a positive lecitovitellase reaction are taken.

Inoculated tubes are placed in a thermostat at 37 ° C for 18-20 hours.

After daily incubation, the isolated strains are checked for morphology, tinctorial properties (Gram stain) and the presence of plasma-coagulating activity and chlorine-forming factor.

Under the microscope, Gram-stained staphylococci look like violet-blue cocci, arranged in clusters or small heaps ("lace").

Plasma coagulation activity is checked in the plasma coagulation reaction (RCP). Taking into account the results of RCP and lecitovitellase activity in 70-75% of cases, on the fourth day of the study, the belonging of the examined strain to the species of Staphylococcus aureus can be confirmed and an appropriate response given.

If the culture has only plasma-coagulating or only lecitovitellase activity, then the final answer requires the determination of other signs of pathogenicity - fermentation of mannitol under aerobic conditions or DNase activity.

Determination of the antibioticogram is carried out only after the isolation of a pure culture. Isolated cultures of Staphylococcus aureus are subject to phage typing.

Accounting for the results of phage typing, determination of antibiotic sensitivity, DNase activity. The final delivery of the response.

Air investigation by sedimentation method is allowed in exceptional cases.

Petri dishes with a nutrient medium (MPA) are placed in open form horizontally, on different levels from the floor. The method is based on the mechanical settling of bacteria on the agar surface in Petri dishes. The media plates are exposed for 10 to 20 minutes, depending on the expected air contamination. To identify pathogenic flora, elective media are used. The exposure in these cases is extended to 2-3 hours. After exposure, the cups are closed, delivered to the laboratory and placed in a thermostat for 24 hours at 37 ° C. The next day, the grown colonies are examined.

Criteria for assessing microbial contamination of air in surgical and obstetric hospitals

Sampling location

Working conditions

Permissible total amount of CFU in 1 m3 of air

Permissible number of colonies of Staphylococcus aureus in 1 m3 of air

Operating and delivery rooms

Before starting work

Not higher than 500

Must not be

During work

Not higher than 1000

No more than 4

Premature and Injured Babies' Wards

Not higher than 500

Must not be

During work

Not higher than 750

Must not be

Breast milk collection and pasteurization rooms

During work

Not higher than 1000

No more than 4

Children's wards

Prepared to receive children

Not higher than 500

Must not be

During work

Not higher than 750

Air microorganisms

Air as a habitat for microorganisms is less favorable than soil and water, since it contains very little or no nutrients for the reproduction of microorganisms. Nevertheless, getting into the air, many microorganisms can persist in it for a more or less long time. Microorganisms are unevenly distributed in the air. There are more microorganisms in dusty and dirty air than in clean air, since they are adsorbed on the surface of solid particles. The air is especially polluted near earth surface, and as you move away from it, it becomes more and more pure. There are more microorganisms in the air of the city center, but less on the outskirts. In summer, there are more microorganisms in the air, less in winter.

Microorganisms are found even in the clouds. At high altitudes, microorganisms are found that form pigments, which increase their resistance to unfavorable living conditions, especially to ultraviolet rays. No microorganisms are found above 84 km above sea level.

The number and species composition of microorganisms in the air ... Under natural conditions, hundreds of species of saprophytic microorganisms are found in the air, represented by cocci (including sarcins), spore-forming bacteria and filamentous fungi, which are highly resistant to ultraviolet rays and other adverse effects. external environment... The air in open spaces is relatively clean, while the air in closed spaces is much more polluted. In the indoor air with poor ventilation, microorganisms accumulate, secreted through the respiratory tract of a person. Pathogenic microorganisms enter the air from sputum and saliva when coughing, talking, sneezing. Even a healthy person, when sneezing and coughing, releases 10 ... 20 thousand CFU into the air, and a sick person - many times more.

The number of microorganisms in the air varies in large ranges: from single bacteria to tens of thousands of CFU / 1m 3. So the air of the Arctic contains 2 ... 3 CFU in 20 m 3, and in cities with industrial enterprises, a huge amount of bacteria is found in the air. In a forest, especially a coniferous one, there are very few microorganisms in the air, and phytoncides of the forest act on them. Above Moscow, at an altitude of 500 m in 1 m 3 of air, from 1100 to 2700 CFU of microorganisms were found, and at an altitude of 2000 m - 500-700 CFU. Spore-forming bacteria and filamentous fungi were found at an altitude of 20 km, other groups of microorganisms - at an altitude of 61 ... 77 km.

A person on average inhales 12,000 ... 14,000 dm 3 of air per day. At the same time, 99.8% of microorganisms contained in the air are retained in the respiratory tract.

Air pollution by pathogenic microorganisms ... When sneezing, coughing and talking, many droplets of liquid are thrown into the air, which contain microorganisms. These droplets can be suspended in air for hours, i.e. form persistent aerosols. Due to moisture, microorganisms in droplets live longer. In such an airborne droplet, infection with many acute respiratory diseases (influenza, measles, diphtheria, pneumonic plague, etc.) occurs. This path of spread of pathogens is one of the main reasons for the development of not only epidemics, but also major influenza pandemics, and in the past, pneumonic plague.

In addition to airborne droplets, pathogenic microorganisms can spread through the air through the "dust" route. This is explained by the fact that the microorganisms in the patient's secretions (drops of sputum, mucus, etc.) are surrounded by a protein substrate, so they are more resistant to drying out and other factors. When such droplets dry out, they turn into a kind of microbial dust containing many pathogenic microorganisms.

Microbial dust particles have a diameter of 1 to 100 microns. For particles larger than 100 microns in diameter, the force of gravity exceeds the air resistance, and they quickly settle. The rate of dust transfer depends on the intensity of the air movement. Microbial dust plays a particularly important role in the epidemiology of tuberculosis, diphtheria, tularemia and other diseases.

To reduce microbial contamination of air in industrial premises apply physical ways its cleaning and disinfection. Using the system supply and exhaust ventilation polluted air is removed from the premises, and cleaner atmospheric air enters its place. Filtration of incoming air through special air filters significantly improves ventilation efficiency.

The most widely used method of air filtration through fibrous porous or granular materials. Despite the fact that fibrous filters have a diameter of at least 5 µm and a weak compaction (spacing of at least 50 µm), they easily trap most microorganisms with an average size of about 1 µm.

The filters, impregnated with a special dust-binding liquid, trap up to 90-95% of microorganisms and dust particles in the air. After cleaning, the air is disinfected. Using fine air filters (FTO), you can achieve cleaning efficiency up to 99.999%. The required degree of air purification in the room is determined by the conditions and nature of the manufactured product. Modern equipment for biological treatment air provides the organization of general and special zones. The biological air purification line, as a rule, includes several technological elements operating in series: an oil filter, a coarse filter, head and individual fine filters. Kit individual elements in the system is determined by a specific production task.

Decontaminated air can be obtained using UV irradiation. For this purpose, the room is equipped with stationary or portable bactericidal lamps at the rate of 2.0-2.5 W / m 3 of the room volume. The operation of the lamps for 6 hours reduces the number of microorganisms in the air by 80-90%. However, it should be borne in mind that the work of ordinary lamps should be carried out in the absence of people, since their radiation has an adverse effect on the skin, mucous membranes of the body and eyes. Disinfection of air in the presence of people can be carried out only using ultraviolet bactericidal irradiators-recirculators, which are designed for periodic and continuous operation.

Usually in the air industrial premises food enterprises should contain no more than 500 CFU / m 3. For some industries, the permissible indicators of the content of microorganisms in the air are more stringent, their values ​​are given in the regulatory documentation.

Air sanitary assessment. The following methods are used to determine air microorganisms:

sedimentation (Koch's method), filtration (air is passed through sterile water);

methods based on the principle of impact action of an air jet using special devices... The latter methods are more reliable, since they allow you to accurately determine the quantitative air pollution by microorganisms and study their species composition.

At food industry enterprises, in production halls and in places where food is stored, it is necessary to observe a certain humidity, temperature and microbiological purity of the air.

The sanitary assessment of indoor air is carried out according to the following indicators: KMAFAnM (the number of mesophilic aerobic and facultative anaerobic microorganisms); the content of mold (filamentous) fungi and yeast; the number of sanitary indicative streptococci in 1m 3 of air.

By the number of cells (CFU) in 1 m 3 of air, one can judge the degree of seeding by streptococcus of human nasopharyngeal microorganisms and, consequently, the possible presence of pathogenic microorganisms in the air.

Air is a medium containing a significant number of microorganisms. They can be transported with air over considerable distances. Unlike water and soil, where microbes can live and multiply, they only remain in the air for a while, and then die under the influence of a number unfavorable factors: drying, the action of solar radiation, temperature changes, lack of nutrients, etc. The most resistant microorganisms can persist in the air for a long time and are found there with great constancy. Such permanent microflora of the air includes spores of fungi and bacteria, sarcins and other pigment-forming cocci.

Relevance of the topic.

It is undeniable that only a healthy person, with good health, is able to live actively, study well, and successfully overcome difficulties. The state of our health depends on a number of factors, including the quality of the air around us. Wherever people are - at work, school or at home, breathing in clean air improves their well-being and performance. Therefore, it is important to know about the state of the air in those rooms where we spend more time. In this regard, the problem of maintaining the cleanliness of the air in school premises, in which we spend 6-7 hours a day, is urgent for us. Today's children spend most of their day at school. Sometimes it seems to us that everyone in our school is just obsessed with cleanliness. The first thing you hear when you go to school is: "Look how much dirt you bring on your feet, and then you will breathe this dust all day." "Do you know how many microbes are in this dust?" No, we do not know, but I can find out how many microbes are in the air of school premises, and what factors influence this.

Objective: to reveal quantitative changes in air microflora in various school premises during the school day using the precipitation method.

To achieve this goal, I need to solve a series tasks:

1. Explore various sources information on the problem under consideration, requirements for the sanitary and hygienic state of the air in classrooms.
2. Master the techniques of working with laboratory equipment, take air samples to determine its purity.
3. Observe the process of growth of bacterial colonies, perform calculations based on the results of the experiment.
4. To study the dynamics of the content of microorganisms in the air during the school day.
5. To develop proposals for improving the state of the air environment in the school.

Research methods:

Theoretical;
-experimental - experiments, observations, comparisons;
-mathematical - making calculations.

Equipment: disposable plastic Petri dishes with dense nutrient medium (MPM), thermometer, magnifying glass, ruler, camera.

Object of study: air environment of school premises.

Subject of study: microflora of the air.

Hypothesis: I suppose that the air of school premises during the day is exposed to pollution, including microbial, and over time, the number of microorganisms in the air increases.

Chapter I. Overview of sources of information on the research problem

1.1. Brief characteristics of microorganisms

Most microbes belong to the bacteria group. This group is widespread in nature, the best studied, therefore the study of microbes usually begins with bacteria.

Bacteria are divided according to the shape of their cells: into spherical - cocci, rod-shaped or cylindrical - bacteria proper - and convoluted - vibrios and spirillae. In addition, there are also filamentous bacteria and myxobacteria. There are numerous and often not noticeable transitions between all these groups, for example, cocco bacteria and others.

Cocci, in turn, are divided by their combination with each other into several subgroups: micrococci, diplococci, streptococci, tetracocci, staphylococci and sarcins.

Among cocci, the most important practical value is streptococcus, which participates in lactic acid fermentation. Many cocci cause various diseases in humans and animals. The causative agent of sore throat belongs to streptococci. Staphylococci and streptococci are pyogenic microorganisms.

When the skin is damaged, various types of injury, as well as when the protective functions of the body are weakened, these microorganisms cause purulent inflammation of the skin, throat, respiratory tract, and so on. Pathogenic streptococci are also causative agents of scarlet fever, rheumatism, secondary mixed infections and many others. All of these pathogens can cause sepsis - blood poisoning.

Rod-shaped bacteria make up the most extensive groups.

This group includes many causative agents of infectious diseases: anthrax, brucellosis, tetanus, intestinal infections. But among the bacteria of this group, there are many useful microbes, for example, intrifiers, and bacteria that assimilate nitrogen from the air.

Coiled bacteria are called spirilla, if they have the form of a spiral with several curls, and vibrios, if they have one curl, not exceeding ¼ of a spiral turn. Typical representatives of vibrios are the causative agent of cholera and water vibrios, very similar to cholera vibrio, but not pathogenic, common inhabitants of fresh water bodies, as well as spirilla.

Filamentous bacteria are long filaments of cells that are joined together. These are mainly aquatic microorganisms.

Myxobacteria (slimy bacteria) are the most highly organized bacteria. Most species have a well-formed nucleus.

The internal structure of bacteria remains insufficiently studied due to technical difficulties in the research methodology.

1.2. Microflora of air

The microflora of the air can be conditionally divided into a constant, often occurring, and a variable, whose representatives, getting into the air from their habitats, do not remain viable for long. Pigment-forming cocci, rods, yeast, fungi, actinomycetes, spore-bearing bacilli and clostridia, etc., that is, microorganisms resistant to light and drying, are constantly found in the air. There are more microorganisms in the air of large cities than in rural areas. Above forests and seas, the air contains few microbes (in 1 m 3 there are units of microbial cells). Rain and snow help purify the air from germs.

There are much more microbes in the air of closed rooms than in open air pools, especially in winter, with insufficient ventilation. The composition of microflora and the number of microorganisms found in 1 m 3 of air (microbial number of air) depend on the sanitary and hygienic regime, the number of people in the room, their state of health and other conditions.

Pathogenic microorganisms from animals, people (patients and carriers) can also get into the air.

Dust particles serve as a favorable environment for the life of various microorganisms. Scientists have found 383 species of bacteria and 28 genera of microscopic fungi in the air. Sources of air pollution are soil, water, plants, animals, humans and waste products of living organisms.

The microflora of the air depends on the microflora of the soil or water, above which the layers of air are located. In soil and water, microbes can multiply, but in the air they do not multiply, but only remain for some time. Raised in the air by dust, they either settle with drops back to the surface of the earth, or die in the air from lack of nutrition and from the action of ultraviolet rays. Therefore, the microflora of the air is less abundant than the microflora of water and soil. The largest number of microbes is contained in the air of industrial cities. The air in rural areas is much cleaner. The microflora of the air differs in that it contains many pigmented, as well as spore-bearing bacteria, which are more resistant to ultraviolet rays (sarcins, staphylococci, pink yeast, miraculous bacillus, hay bacillus and others). The air in closed rooms is very rich in microbes, especially in cinemas, train stations, schools, livestock buildings and others.

Along with harmless saprophytes in the air, especially in closed rooms, there may be pathogenic microbes: tubercle bacillus, streptococci, staphylococci, influenza pathogens, whooping cough, and so on. Influenza, measles, whooping cough are infected exclusively by airborne droplets. When coughing, sneezing, tiny aerosol droplets containing pathogens are thrown into the air, which are inhaled by other people and, having become infected, become ill. Microbiological analysis of air for pathogenic flora is performed only for epidemic indications.

The cleaner the air in public places, around human habitation and in rooms, the less people get sick. It is estimated that if you brush the vacuum cleaner over the surface of an object four times, up to 50% of the germs are removed, and if twelve times, almost 100%. Forests and parks are of great importance in the struggle for air purity. Green spaces settle, absorb dust and release phytoncides that kill microbes.

Microbes are not only harmful to human health. Pathogens of diseases of animals and plants also spread through the air. Microorganisms, together with dust, settle on food products, causing them to sour, putrefactive decomposition.

In a planned manner, air samples for bacteriological examination are taken in operating blocks, recovery wards, intensive care units, intensive care units and other rooms requiring aseptic conditions. For epidemic indications, the air of nurseries, kindergartens, schools, factories, cinemas and so on is subjected to bacteriological testing.

The detection of hemolytic group A streptococcus and staphylococcus, which has signs of pathogenicity in the air of closed rooms, are an indicator of the epidemic trouble of this object.

1.3. Sanitary and microbiological air research

The air environment, as an object of sanitary and microbiological research, has whole line specific features. As a rule, among them, first of all, there are:
- lack of nutrients and, as a result, the impossibility of reproduction of microorganisms;
- short-term presence of microorganisms in the air phase and their spontaneous sedimentation;
- low concentrations of microorganisms in the air;
- a relatively small number of species of microorganisms found in the air.

Microorganisms are in the air in the form of an aerosol. Microbial aerosol is a suspension in the air of living or killed microbial cells, adsorbed on dust particles or enclosed in “droplet nuclei”. It includes particles ranging in size from 0.001 to 100 microns. Particle size determines 2 important parameter aerosol:

1.the rate of settling (sedimentation) - for particles ranging in size from 10 to 100 microns is 0.03 - 0.3 m / s. Particles of the specified size settle on the surface in 5-20 minutes. Particles with a size of 5 microns or less form a practically non-sedimenting aerosol of particles constantly suspended in the air;

2. Penetrating ability of particles - the most dangerous are particles with a size of 0.05 to 5 microns, since they are retained in the bronchioles and alveoli. It is this fraction of dust particles that is taken into account in modern classification clean rooms in accordance with GOST R 50766 - 95. Particles with a size of 10 microns and more are retained in the upper respiratory tract and are removed from them.

The danger of microbial aerosol for human health is due not only to the existence of an aerosol transmission mechanism in a number of infectious diseases. Microbial aerosol can also cause the development of allergies, as well as intoxication (poisoning) associated with inhalation of endotoxins from gram-negative bacteria, gram-positive bacteria and mycotoxins from molds. In addition, the presence of microbial aerosols in the air is undesirable in a number of technological processes.

1.4. Methods for microbiological studies of the qualitative and quantitative composition of bacteria in the air

For studying various properties microbes in microbiology, a method of artificially growing them on special media has been developed. Microorganisms in natural conditions usually found in the form of communities of various types. An accurate study of individual species is possible only by isolating them in pure cultures, that is, in cultures containing only one type of microbes. Pasteur was the first to develop special methods for the study of microbes. Further improvement of methods of bacteriological research belongs to the prominent German scientist R. Koch.

Currently, they use natural and artificial environments, liquid and dense. Natural environments include: skim milk, unhopped wort, decoctions of peas, pieces of potatoes, and others. There are a lot of artificial environments. Peptone media are used for heterotrophic bacteria. Peptone is a product of incomplete breakdown of animal proteins. This is peptone water (1 g of peptone, 0.5 table salt per 100 ml of water). In mesopatamia broth, the same amount of peptone and salt is added to meat broth from which protein substances are precipitated. These liquid media can be made dense by adding 1-3% food grade agar to them. Agar is a substance extracted from seaweed. Its value lies in the fact that the agar medium solidifies in the form of a transparent jelly and does not liquefy if it is not heated to a boil. The medium must have a certain reaction (pH), must be sterile. Crops are grown at a specific temperature. Meat-peptone agar is very widely used in microbiology, since almost all types of microorganisms grow on this substrate, and therefore, it is applicable for the primary identification of air bacteria.

In the study of indoor air, the method of isolating microorganisms from the air is of great importance. Depending on the principle of trapping bacteria, microbiological methods for studying air are divided into sedimentation, filtration and aspiration. The method of natural sedimentation is based on the deposition of microorganisms under the action of gravity on the surface of a dense nutrient medium. An open Petri dish with a nutrient medium is left on a horizontal surface for a certain time. Then the dish is closed and after incubation in a thermostat, the grown colonies are counted. It should be noted that the results obtained in this case turn out to be underestimated, in comparison with the data obtained using the Krotov device, by an average of three times, since fractions with particles less than 100 μm practically do not settle. In this regard, attempts were made repeatedly to correct the calculation scheme, but they did not end with the development of a generally accepted calculation method. At present, many authors, citing the results of measurements made using the sedimentation method, limit themselves to indicating the number of colonies, the time of sampling and the diameter of the Petri dish. To determine the type of microbes crucial have: features of the surface of the colonies (smooth, rough, convex, bumpy), its edges (even, jagged), color, size of the colonies.

The number of microbes in working and living quarters is closely related to the sanitary and hygienic regime of the premises: the size of the room, lighting conditions, the quality of cleaning, the frequency of ventilation and other factors. With a crowd of people, poor ventilation, poor natural lighting, improper cleaning of premises, the number of microbes increases. Dry cleaning, occasional washing of floors, the use of dirty rags and brushes, and drying them in the same room create favorable conditions for the accumulation of microbes in the air.

The sanitary and hygienic state of indoor air is determined by two indicators:

microbial number - the content of the total number of microorganisms in 1 m 3 of air;
the number of sanitary-indicative bacteria - hemolytic streptococci and pathogenic staphylococci in 1 m 3 of air;

Particularly strict sanitary and hygienic requirements are imposed on the air in operating rooms, maternity hospitals, hospital wards and child care facilities.

For disinfection of indoor air, use germicidal lamps of various capacities. Irradiation of the air with such lamps leads to rapid inactivation and complete death of viruses and bacteria. Sometimes for disinfection of indoor air, a method of spraying chemical antiseptics is used - propylene glycol, triethylene glycol, odorless and non-toxic to humans.

Microbes can be spread by currents of air, airborne dust and airborne droplets. Pathogens of influenza, measles, acute respiratory infections, scarlet fever, diphtheria, whooping cough, tonsillitis, tuberculosis and other diseases can be transmitted through the air along with drops of mucus and sputum when sneezing, coughing, talking. When sneezing, coughing, talking, a sick person throws out pathogenic bacteria along with drops of mucus, sputum into environment radius of 1 - 1.5 m and more.

Pathogenic microorganisms can be transmitted through the air by airborne dust. 1 g of dust contains up to 1 mln. various bacteria, including pathogenic fungi. Pyogenic streptococci and staphylococci, mycobacterium tuberculosis, anthrax bacilli, tularemia bacteria, salmonella, etc. can be transmitted by airborne dust.

During epidemics, in order to protect people from infection with pathogenic microorganisms through the air, it is recommended that wet cleaning and frequent ventilation of premises, cotton-gauze masks, burning or disinfecting the sputum of patients are recommended.

Chapter II. Research methodology

The study of the air microflora was carried out in November 2014 in the premises of the MBOU OOSh No. 18 of the village of Kislyakovskaya and included a number of stages:

1. Preparation of an artificial culture medium.
2. Growing microorganisms by precipitation from the air.
3. Quantitative calculation of microorganisms in the air.
4. Carrying out statistical processing of the material and analysis of the data obtained.

2.1. Preparation of an artificial culture medium.

First, I made a beef broth at home (I passed 500 g of meat without bones and fat through a meat grinder). Minced meat in an enamel pan was poured with water (1 liter) and left for 24 hours at a temperature of 7 ° C. Then the minced meat was boiled for 30 minutes. Chilled and filtered. Then I added 1 g of salt and 1 g of peptone to 100 g of broth, brought it to a boil again and filtered it a second time. Added a 10% solution of baking soda to neutralize the broth to a slightly alkaline reaction. In the resulting MPB added 20 g of gelatin. Received mesopatamia gelatin. I sterilized the Petri dishes, poured the same amount of NRM into them, closed them, and left them to solidify.

2.2. Cultivation of microorganisms by precipitation from the air.

To determine the presence of microorganisms in the air, I used the method of growing them on culture media, sowing directly on the nutrient medium (Koch sedimentation method). The Koch settling method is used only when studying indoor air and is suitable for comparative assessments of air purity. The degree of air pollution is judged by the number of colonies that have grown.

First, together with the teacher, we identified the study rooms. We chose rooms in which the temperature was the same (20-22 ° С): geography office - no. 11 (sunny side), chemistry / biology office (shady side) - no. 12, 1st floor corridor, school canteen and dressing room.

Wardrobe

1st floor corridor

Canteen

Office number 11

Office number 12

Microbiological analysis was carried out three times during one day: early in the morning, before the arrival of the students; then at the third break, with the active movement of schoolchildren, and after the sixth lesson before wet cleaning.

Petri dishes filled with mesopatamia gelatin, pre-numbered with a marker, placed at the indicated points and left open for 10 minutes. Together with dust and moisture droplets, microbes also settle on the surface of the NRM. After the set time had elapsed, the cups were covered with lids, placed in a homemade thermostat and kept in a laboratory biology laboratory at 25 ° C for 7 days.

2.3. Quantitative calculation of microorganisms in the air

After 7 days, a count of the grown colonies is made, assuming that each colony has grown from one settled microbial cell. It has been established that in 10 minutes the amount of microorganisms contained in 10 liters of air will settle on an area of ​​100 cm 2.

Knowing the number of colonies that have grown in a Petri dish, and its area (at 9 cm it is equal to 63.6 cm 2), you can calculate how many microorganisms are contained in 10 liters of air. So, if A microorganisms settle on an area equal to 63.6 cm 2, then X microorganisms are contained on an area equal to 100 cm 2:

Multiplying the result by 100, determine the content of microorganisms in 1 m 3, or 1000 liters of air

The description of the colonies of microbes grown on a nutrient medium is carried out according to the following indicators: shape (round, irregular); surface (smooth, shiny, rough, dry, folded); edge (smooth, wavy, crenate); color; size (diameter).

It should be noted that the method of counting colonies in Petri dishes with inoculation from air gives only approximate data. Only microbes of rapidly settling dust are taken into account, in addition, only aerobic forms of microorganisms will germinate on a solid nutrient surface. The sedimentation method of sampling (Koch) does not allow determining the exact number of microorganisms in the air, it only gives an approximate estimate of the microflora. Nevertheless, the results of such studies make it possible to obtain the big picture air pollution.

2.4. Statistical processing of the material

Statistical processing of the data obtained was carried out according to the method of B. A. Dospekhov.

The count of bacteria inoculation from the air is carried out by counting the grown bacterial colonies separately. Knowing the area of ​​the Petri dish, you can determine the number of microorganisms in 1 m 3 of air. For this:
1) the area of ​​the nutrient medium in the Petri dish is determined by the formula πr 2;
2) calculate the number of colonies in an area of ​​1 dm 2;
3) recalculate the number of bacteria per 1 m 3 of air.

Approximate calculation:

25 colonies grew in a Petri dish 10 cm in diameter.
1) determine the area of ​​the nutrient medium in the Petri dish according to the formula 3.14 * 5 2 = 3.14 * 25 = 78.5 cm 2
2) calculate the number of colonies in an area of ​​1 dm 2 equal to 100 cm 2
25 colonies - 78.5 cm 2
x = 25 * 100 / 78.5 = 32 colonies
x colonies - 100 cm 2
that is, there are 32 colonies on an area of ​​1 dm 2.
3) recalculate the number of bacteria per 1 m 3 of air, which is equal to 1000 liters. Contained 32 colonies of bacteria on an area of ​​1 dm 2 correspond to a volume of 10 liters of air. To find out the amount in 1 m 3 of air, make up the proportion:
32 – 10
x = 32 * 1000/10 = 3200
x - 1000
Consequently, 1 m 3 of air contains 3200 bacterial bodies.

Chapter III. Results and its discussion

During the studies, three Petri dishes were used for each microbiological assessment. Colonies of microorganisms grown on the NRM medium are shown in the photo (results of microbiological analysis at the 3rd break):

Office number 11

Office number 12

Canteen

Wardrobe

1st floor corridor

Based on the count of colonies grown in Petri dishes, an assessment of the content of microorganisms that are contained in the air was carried out various premises at different periods of the school day.

The results of this study were compared with the criteria for the sanitary assessment of the air in living quarters (Table 1) and presented in Table 2.

Table # 1. Criteria for the sanitary assessment of residential air

Table 2. The number of microorganisms contained in 1 m 3 of school air during the school day

Then a comparative analysis of the microflora of school premises was carried out throughout the school day (Diagrams 1-3).

Diagram 1.Sanitary assessment of air in the premises of the Kislyakovskaya MBOU OOSh No. 18 in the morning (microorganisms in 1m 3)

Diagram 2.Sanitary assessment of air in the premises of the Kislyakovskaya MBOU OOSh No. 18 at the 3rd break (microorganisms in 1m 3)

Diagram 3.Sanitary assessment of air in the premises of the Kislyakovskaya MBOU OOSh No. 18 after the 6th lesson (microorganisms in 1m 3)

She revealed a tendency for an increase in the number of microorganisms in all school premises compared to the morning test, which is apparently associated with the intensity of movement of people. Based on the data obtained, the most contaminated room with microorganisms is the dressing room, the corridor of the 1st floor, then office no. 12, dining room and office no. 11.

The high pollution of the dressing room is explained by the high intensity of movement of people, all 134 schoolchildren pass through it, and air was taken while undressing and dressing students, which increased the circulation of dust - the main carrier of microorganisms. The high pollution of the 1st floor corridor is explained by the fact that there is a higher air temperature + 24 ° С and a high traffic intensity during the whole school day. Based on the fact that microorganisms multiply abundantly in warm and humid environments, on residues food products, on dust particles in darkened places of the premises, we can say that the high microbiality detected in the premises is natural. The increased number of microorganisms after school can be explained both by the increase in air pollution by the end of the school day, and by the intensity of traffic. But the level of microbial contamination, based on the standards, in all rooms, except for the wardrobe, is not exceeded.

After the 6th lesson, the air in the office No. 11 and the dining room turned out to be cleaner in comparison with other rooms, this can be explained by the fact that wet cleaning has already taken place. The small number of colonies of microorganisms in room 11 indicates that there are no favorable conditions for their development (sunny side).

Conclusions on work

The results of this study generally support my hypothesis.

1. The smallest number of microorganisms was detected in the air samples of the first experiment (in the morning).
2. The level of microbial contamination in the premises of the Kislyakovskaya MBOU OOSh No. 18, except for the wardrobe, does not exceed the standard.
3. Indoor air does contain bacteria, the number of which increases during the day under the influence of various factors.
4. When found a large number people indoors, the number of microorganisms in the air increases.
5. Wet cleaning and airing the room helps to reduce dust and bacteria in the air.

1. To oblige those on duty at the big break to open the windows.
2. To clean the premises more often with the use of disinfectants.
3. Clothes should be given out by a wardrobe employee through a window or door.
4. At the entrance to the school, lay out rugs that remove mechanical dirt from shoes.

Conclusion

So, at this stage of my project, I can say that germs get into the air mainly with the rising dust, so keeping the rooms clean is very important. Together with the teacher, we plan to continue our research in the warm season and compare the results obtained with the data of this work. In addition, you can carry out a comparative analysis of one room at different periods of time, if there are additional factors:
1) ventilation of the room,
2) the number of people and the intensity of their movement,
3) the effect of phytoncidal activity of plants on the microflora of school premises.

We did not take air samples in the gym due to its renovation, which is planned to be done in the future.

Well, my little observation, which is based not only on scientific, but also on everyday experience. Students primary school they always change into removable shoes, but middle and senior students are often lazy to do this. As it turned out, in vain. Creating a safe environment around us, schoolchildren, is a concern not only of the cleaning ladies or on-duty teachers, but of ourselves as well.

List of used sources of information

1. Anikeev V.V., Lukomskaya K.A. Guide to practical training in microbiology. - M .: "Education", 1983.
2. Vasilyeva ZP, Kirillova G.A., Laskina A.S. Laboratory work in microbiology. - M .: "Education", 1979.
3. Gusev M. V., Mineeva L. A. Microbiology. Third edition. - M .: Rybari, 2004
4. Dospekhov B.A. Field experiment technique. - M .: "Agropromizdat", 1985.
5. Kashkin P.N., Lisin V.V. A practical guide on medical mycology. - L .: Medicine, 1983.
6. Labinskaya A. S. Microbiology with the technique of microbiological research, M, Medicine, 1978.
7. Pasechnik V.V. School workshop. Ecology, 9 cl. - M .: Bustard, 1998.
8. SanPiN 2.4.2.2821-10 "Sanitary and epidemiological requirements for the conditions and organization of training in educational institutions"
9. Directory. Sanitary Microbiology, Ministry of Health of the State Medical Academy named after Mechnikova I.I., SP, 1998.
10.http: //www.webmedinfo.ru/library/mikrobiologija.php
11.http: //ayp.ru/shpargalki/biologiya/1/Page-19.php
12.http: //www.ebio.ru/gri06.html

Work completed:
Rud Sophia Grigorievna
student of grade 7 MBOU OOSh number 18

Scientific adviser:
Fomenko Elena Vladimirovna
teacher of chemistry, biology MBOU OOSh number 18

Municipal budgetary educational institution
basic secondary school number 18

Krasnodar region
Kushchevsky district
village Kislyakovskaya
2014