Resident microflora is called microflora. Resident microflora

Microflora of the human body (Automicroflora)

This is an evolutionarily formed qualitatively and quantitatively relatively constant set of microorganisms, all biocenoses, individual biotopes of the body.

The child is born sterile, but still goes through birth canal, captures the accompanying microflora. The formation of microflora is carried out as a result of contact of a newborn with microorganisms environment and microflora of the mother’s body. By the age of 1-3 months, the child’s microflora becomes similar to the microflora of an adult.

The number of microorganisms in an adult is 10 in 14 individuals.

1. Several hundred thousand bacteria may be present per 1 cm2 of skin

2. With each breath, 1500-14000 or more microbial cells are absorbed

3. 1 ml of saliva contains up to 100 million bacteria

4. The total biomass of microorganisms in the large intestine is about 1.5 kg.

Types of microflora of the body

1. Resident microflora - permanent, indigenous, autochthonous
2. Transitory - unstable, allochthonous

Function of microflora

1. Colonization resistance is a normal microflora that prevents the colonization of body biotopes by outsiders, including pathogenic microorganisms.
2. Digestion and detoxification of exogenous substrates and metabolites
3. Immunization of the body
4. Synthesis of vitamins, amino acids, proteins
5. Participation in exchange bile acids, uric acid, lipids, carbohydrates, steroids
6. Anticarcinogenic effect

Negative role of microflora

1. Opportunistic representatives of normal microflora can become a source endogenous infection. Normally, these microorganisms do not cause trouble, but when the immune system is weakened, for example staphylococcus, they can cause a purulent infection. E. coli is in the intestines, and if it ends up in the bladder, it’s cystitis, and if it gets into a wound, it’s a purulent infection.

1. Under the influence of microflora, the release of histamine may increase - allergic conditions

1. Normoflora is a repository and source of antibiotic resistance plasmids.

The main biotopes of the body -

1. Inhabited biotopes - in these biotopes bacteria live, reproduce and perform certain functions.
2. Sterile biotopes - in these biotopes there are normally no bacteria; isolating bacteria from them has diagnostic value.

Inhabited biotopes -

1. Airways
2. External genitalia, urethra
3. Outer ear canal
4. Conjunctiva

Sterile biotopes - blood, cerebrospinal fluid, lymph, peritoneal fluid, pleural fluid, urine in the kidneys, ureters and bladder, synovial fluid.

Skin microflora- epidermal and saprophytic staphylococci, yeast-like fungi, diphtheroids, micrococci.

Microflora of the upper respiratory tract - streptococci, diphtheroids, neisseria, staphylococci.

Oral cavity- staphylococci, streptococci, yeast-like fungi, lactobacteria, bacteroides, neisseria, spirochetes, etc.

Esophagus- normally does not contain microorganisms.

In the stomach - habitat - extremely unpleasant - lactobacilli, yeast, occasionally staphylococci and streptococci

Intestines- the concentration of microorganisms, their species composition and ratio varies depending on the intestinal section.

U healthy people V duodenum the number of bacteria is not more than 10 in 4 - 10 in 5 colony forming units (cfu) per ml.

Species composition - lactobacilli, bifidobacteria, bacteroides, entrococci, yeast-like fungi, etc. With food intake, the number of bacteria can increase significantly, but short term, returns to the original level.

IN upper sections small intestine - number of microorganisms - 10 in 4 -10 in 5 colony forming units per ml, in ileum up to 10 to the 8th power.

Mechanisms that inhibit microbial growth in the small intestine.

1. Antibacterial effect of bile
2. Intestinal peristalsis
3. Isolation of immunoglobulins
4. Enzyme activity
5. Mucus containing microbial growth inhibitors

If these mechanisms are violated, microbial contamination of the small intestine increases, i.e. overgrowth of bacteria in the small intestine.

IN colon in a healthy person, the number of microorganisms is 10 in 11 - 10 in the 12th colony per city. Anaerobic species of bacteria predominate - 90-95% of the total composition. These are bifidobacteria, bacteroides, lactobacteria, veillonella, peptostreptococci, clostridia.

About 5-10% are facultative anaerobes - and aerobes - E. coli, lactose negative enterobacteria, enterococci, staphylococci, yeast-like fungi.

Types of intestinal microflora

1. Parietal - constant in composition, performs the function of colonization resistance
2. Luminal - less constant in composition, performs enzymatic and immunizing functions.

Bifidobacteria- the most significant representatives of obligate (obligatory) bacteria in the intestine. These are anaerobes, do not form spores, are gram positive rods, the ends are forked, and may have spherical swellings. Most bifidobacteria are located in the large intestine, being its main parietal and luminal microflora. The content of bifidobacteria in adults is 10 in 9th - 10 in 10th cfu. on the city

Lactobacilli- another representative of the obligate microflora of the gastrointestinal tract is lactobacilli. These are gram positive rods, with pronounced polymorphism, arranged in chains or singly, and do not form spores. Lactoflor can be found in human and animal milk. Lactobacilli (lactobacillus). Content in the large intestine - 10 in the 6th - 10 in the 8th c.u. on the city

A representative of the obligate intestinal microflora is Escherichia (Escherichia colli). - Escherichia coli. The content of E. coli is 10 to the 7th degree - 10 to the 8th degree c.u. on the city

Eobiosis - microflora - normal flora. The biological balance of normal flora is easily disturbed by factors of exogenous and endogenous nature.

Dysbacteriosis- changes in the qualitative and quantitative composition of microflora as well as in their normal habitats.

Intestinal dysbiosis is a clinical and laboratory syndrome associated with changes in the qualitative and/or quantitative composition of the intestinal microflora, with the subsequent formation of metabolic and immunological disorders, with possible development gastrointestinal disorders.

Factors contributing to the development of intestinal dysbiosis

1. Gastrointestinal disease
2. Starvation
3. Antimicrobial chemotherapy
4. Stress
5. Allergic and autoimmune diseases
6. Radiation therapy
7. Exposure to ionizing radiation

Most typical clinical manifestations

1. Abnormal bowel movements - diarrhea, constipation
2. Abdominal pain, flatulence, bloating
3. Nausea and vomiting
4. General symptoms are fatigue, weakness, headaches, sleep disturbances, and possible hypovitaminosis.

According to the degree of compensation they distinguish -

1. Compensated dysbacteriosis - there are no clinical manifestations, but bacteriological examination reveals abnormalities.
2. Subcompensated dysbacteriosis - minor, moderate graphic applications.
3. Decompensated - when clinical manifestations are most pronounced.

Classification by species or group of organisms

1. Excess of staphylococcus - staphylococcal disbacteriosis
2. Dysbacteriosis caused by conditionally pathogenic enterobacteria, yeast-like fungi, associations of conditionally pathogenic microorganisms, etc.

Dysbacteriosis is a bacteriological concept, a clinical and laboratory syndrome, it is not a disease. Dysbacteriosis has a primary cause.

Diagnosis of microflora composition disorders

1. Clinical and laboratory diagnostics and identification of the causes of the disorder
2. Microbiological diagnosis with determination of the type and degree of qualitative and quantitative violations microflora composition.
3. Study of immune status.

Microbiological diagnostics. Violation of the composition of the body's microflora.

Preliminary stage - microscopic examination of stool - smear and gram stained

Bacteriological or cultural examination. This method has been used for many years. A sample of feces is suspended in a buffer solution. Prepare a dilution from 10 to -1 to 10 to -10 degrees. Sowing is carried out on a nutrient medium. The grown microorganisms are identified by cultural, morphological, tinctorial, biochemical and other properties, and microflora indicators are calculated - CFU/g of feces.

Nutrient media -

Blaurock's medium - for isolating bifidobacteria

MRS agar for the isolation of lactobacteria

Endo, Ploskirev, Levin medium - for isolating E. coli and opportunistic enterobacteria.

JSA - staphylococci

Wilson - Blair medium - spore-forming anaerobes - clostridia

Sabouraud's medium - yeast-like fungi - genus Candida

Blood MPA - hemolytic microorganisms

The principles of correcting disturbances in the composition of microflora are nonspecific - regimen, diet, decontamination of body biotopes, from pathogenic and conditionally pathogenic microorganisms.

Probiotics and prebiotics

Correction of immune system disorders.

Probiotics and eubiotics are preparations that contain live microorganisms that have a normalizing effect on the composition and biological activity microflora of the digestive tract.

Requirements for probiotics.

1. Compliance with normal human microflora
2. High viability and biological activity
3. Antagonism towards pathogenic and conditionally pathogenic microflora
4. Resistance to physical and chemical factors
5. Antibiotic resistance
6. Presence of symbiotic strains in the product

Classification of probiotics

1. Classic monocomponent - bifidumbacterin, colibacterin, lactobacterin
2. Multicomponent - bificol, acylact, linex
3. Self-eliminating antagonists - bactisubtil, sporobacterin, eubicor, enterol
4. Combined - bifiform
5. Probiotics containing recombinant strains
6. Prebiotics - hilak forte, lactulose, galacto and fructooligosaccharides
7. Synbiotics - acipol, normoflorin

Prebiotics- drugs that create favorable conditions for the existence of normal microflora.

Synbiotics- preparations containing a rational combination of probiotics and prebiotics.

Bacteriophage preparations- specificity of action on certain microorganisms.

The superficial layer of the epidermis (the top layer of skin) is completely replaced every 2 weeks. Daily from healthy skin Up to 100 million skin flakes are shed, of which 10% contain viable bacteria. Skin microflora can be divided into two large groups:

I. Resident flora

II. Transitory flora

Resident microflora

Microorganisms representing resident (normal, permanent, colonizing) flora, constantly live and reproduce on the skin. Approximately 10-20% of them can be located in the deep layers of the skin, including sebaceous and sweat glands ah, hair follicles.

The largest number of resident microbes on the hands is found around and under the nails and, to a lesser extent, between the fingers.

Resident microorganisms are almost impossible to completely remove or destroy through routine hand washing or even antiseptic procedures, although their numbers can be significantly reduced.

Sterilization of the skin of the hands is not only impossible, but also undesirable: normal microflora prevents the colonization of the skin by other, much more dangerous microorganisms, primarily gram-negative bacteria.

Transient microflora

These are the microorganisms that are acquired medical personnel as a result of contact with infected patients or contaminated environmental objects. Transitory flora can be represented much more epidemiologically dangerous microorganisms (E.coli, Klebsiella spp., Pseudomonas spp., Salmonella spp. and other gram-negative bacteria, S.aureus, C. albicans, rotaviruses, etc.), including hospital strains of pathogens of nosocomial infections.

Transient microorganisms persist on the skin of the hands a short time(rarely more than 24 hours). They can be easily removed by regular hand washing or destroyed by using antiseptics. While these microbes remain on the skin, they can be transmitted to patients through contact and contaminate various objects. This circumstance makes the hands of the staff the most important factor transmission of nosocomial infection.

If the skin is damaged (including as a result of inadequate washing and hand antisepsis), transient microorganisms can colonize and infect the skin for a long time, forming a new, much more dangerous resident (but not normal) flora. In these circumstances, hands medical workers can be not only a factor in the transmission of infection, but also a reservoir for it, and the sanitation of such carriers (which can only be identified through a special bacteriological examination) is very difficult, if not impossible.

Traditionally, there are three levels of hand treatment (decontamination):

1. Social level (hygienic hand washing with soap and water to remove contaminants and reduce microorganisms)

2. Hygienic level (hand treatment using skin antiseptics)

3. Surgical level (a special sequence of manipulations when treating hands followed by putting on sterile gloves)

present:

Staphylococcus epidermidis;

Staphylococcus aureus;

Micrococcus spp.;

Sarcina spp.;

Coryneform bacteria;

Propionibacterium spp.

As part of the transitory:

Streptococcus spp.;

Peptococcus spp.;

Bacillus subtilis;

Escherichia coli;

Enterobacter spp.;

Acinetobacter spp.;

Lactobacillis spp.;

Candida albicans and many others.

In areas where there are accumulations sebaceous glands(genitals, outer ear), found acid-fast non-pathogenic mycobacteria.

The most stable and at the same time very convenient for studying is microflora of the forehead area.

The vast majority of microorganisms, including pathogenic ones, do not penetrate intact skin and die under the influence of the bactericidal properties of the skin. Among these factors that can have a significant impact on the removal of non-permanent microorganisms from the skin surface, relate:

Acidic reaction of the environment;

Availability fatty acids in the secretions of the sebaceous glands and the presence of lysozyme.

Neither profuse sweating, neither washing or bathing can remove the normal permanent microflora or significantly affect its composition, since microflora is quickly restored due to the release of microorganisms from the sebaceous and sweat glands, even in cases where contact with other areas of the skin or with the external environment is completely stopped. Therefore, an increase in the contamination of a particular area of ​​the skin as a result of a decrease in the bactericidal properties of the skin can serve as an indicator of a decrease in the immunological reactivity of the macroorganism.

2. In the normal microflora of the eye (conjunctiva) The dominant microorganisms on the mucous membranes of the eye are the following:

Diphtheroids (coryneform bacteria);

Neisseria;

Gram-negative bacteria, mainly of the genus Moraxella.

Often found:

Staphylococcus;

Streptococci;

Mycoplasmas.

The quantity and composition of conjunctival microflora is significantly influenced by tear fluid, which contains lysozyme, which has antibacterial activity.

3. Feature normal microflora of the ear is that the middle ear does not normally contain microbes, since earwax has bactericidal properties. But they can still penetrate the middle ear through eustachian tube from the throat.

In the external auditory canal there may be skin inhabitants:

Staphylococcus;

Corynebacteria;

Less common bacteria of the genus Pseudomonas;

Mushrooms of the genus Candida.

4. For normal microflora of the upper respiratory tract typical almost complete absence microorganisms from the external environment, since most of them linger in the nasal cavity, where they die after some time.

Own microflora of the nosepresented:

Corynebacteria (diphtheroids);

Neisseria;

Coagulase-negative staphylococci;

Alpha hemolytic streptococci.

May be present as transient species:

Staphylococcus aureus;

Escherihia coli;

Beta-hemolytic streptococci.

Microbiocenosis of the pharynx is even more diverse, since the microflora of the oral cavity and airways mixes here.

Representatives of the resident microflora are considered:

Neisseria;

Diphtheroids;

Alpha hemolytic;

Gamma-hemolytic streptococci;

Enterococci;

Mycoplasmas;

Coagulase-negative staphylococci;

Moraxella;

Bacteroides;

Borrelia;

Treponema;

Actinomycetes.

In the upper respiratory tractprevail:

Streptococci;

Neisseria; meet:

Staphylococcus;

Diphtheroids;

Haemophilus influenzae bacteria;

Pneumococci;

Mycoplasmas;

Bacteroides.

Mucous membrane of the larynx, trachea, bronchi and all underlying sectionskept sterile due to the activity of their epithelium, macrophages, as well as the production of secretory immunoglobulin A.

The imperfection of these protective mechanisms in premature infants, disruption of their functioning as a result of immunodeficiency states or inhalation anesthesia leads to the penetration of microorganisms deep into the bronchial tree and, accordingly, may be one from causes of severe respiratory diseases.

5. As part of the normal microflora of the oral cavity and digestive tract currently described several hundred species of microorganisms.

Already when passing through the birth canal may happen contamination of the mucous membrane of the child’s mouth and pharynx.

4-12 hours after birthas part of the oral microflora detect viridans (alpha-hemolytic) streptococci, which accompany a person throughout his life. They probably enter the child’s body from the mother’s body or from service personnel.

To these microorganisms already in early childhood are added:

Staphylococcus;

Gram-negative diplococci (Neisseria);

Corynebacteria (diphtheroids);

Sometimes lactic acid bacteria (lactobacillus).

During teething on mucous membranes settle in:

Anaerobic spirochetes;

Bacteroides;

Fusobacteria;

Lactobacilli.

Promotes faster formation of normal intestinal microflora early breastfeeding and breastfeeding.

The normal microflora includes:

Resident, or permanent, microflora, which is represented by a relatively stable composition of microorganisms, usually found in certain places of the human body in people of a certain age;

Transitional, or temporary microflora that enters the skin or mucous membranes from the environment, without causing diseases and not permanently living on the surfaces of the human body. It is represented by saprophytic opportunistic microorganisms that live on the skin or mucous membranes for several hours, days or weeks. The presence of transient microflora is determined not only by the supply of microorganisms from the environment, but also by the state of the host’s immune system and the composition of the permanent normal microflora.

5. What factors influence changes in the species and quantitative composition of human normal flora?

Factors influencing changes in human normal flora:

Deterioration of the ecological state of anthropogenic origin.

Exposure to xenobiotics (industrial and household pollutants, biochemically foreign compounds, pesticides, herbicides, nitrates, nitrites, growth stimulants, etc.).

Exposure to radiation, excessive ultraviolet exposure.

Unbalanced diet(deficiency of dietary fiber, micro and macroelements, excess of canned and refined foods, lack of vitamins, etc.).

Inappropriate use of antibiotics.

Intestinal infections of both bacterial and viral etiology.

Physical and emotional stress.

Chemotherapy and hormone therapy, treatment with cytostatics and immunosuppressants.

Physical inactivity, alcohol abuse.

Chronic inflammatory diseases Gastrointestinal tract, especially with secretory insufficiency, persistent gastrointestinal dyskinesia.

Anomalies in the structure of the gastrointestinal tract, congenital and acquired as a result of injuries, diseases and operations.

Immunodeficiency conditions of various origins.

Chronic infections.

Metabolic diseases (including diabetes, atherosclerosis and others).

Allergies, especially those related to the gastrointestinal tract.

6. What differences in the composition of microflora are noted in various departments intestines?

The human gastrointestinal tract is normally populated a huge amount microorganisms. The concentration of microbial cells, their composition and ratio varies depending on the intestinal section.

In healthy people duodenum the number of bacteria is no more than 104 -105 CFU (colony-forming units - i.e. living microorganisms) per ml of content. Species composition of bacteria: lactobacilli, bifidobacteria, bacteroides, enterococci, yeast-like fungi, etc.

In the upper parts of the small intestine, microorganisms are detected in small quantities, no more than 104 -105 CFU/ml of contents.

In the ileum, the total number of microorganisms is up to 108 CFU/ml of chyme.

In the colon of a healthy person, the number of microorganisms is 1011 -1012 CFU/g of feces. Anaerobic species of bacteria predominate (90-95% of the total composition): bifidobacteria, bacteroides, lactobacilli, veillonella, peptostreptococci, clostridia. About 5-10% of the microflora of the large intestine is represented by aerobes: Escherichia coli, lactose-negative enterobacteria (Proteus, Enterobacter, Citrobacter, Serration, etc.), enterococci (fecal streptococci), staphylococci, yeast-like fungi.

7. What is the reason for the low content of microorganisms in the stomach?

The stomach contains a small number of microorganisms, this is due to the fact that gastric juice has a bactericidal effect. The most commonly found are acid-fast gram-positive lactobacilli, staphylococci, streptococci, micrococci, and fungi of the genus Candida. Sarcines and Helicobacter pylori may be detected.

8. Which biotope of the human body contains microorganisms that provide colonization resistance?

The biotopes in which bacteria live, multiply and perform certain functions are: skin, airways, gastrointestinal tract, external genitalia, urethra, external auditory canal, conjunctiva.

Colonization resistance is a set of microorganisms that impart stability to the normal flora and prevent the colonization of the host organism by foreign microorganisms.

9. What is selective decontamination?

Selective decontamination is the selective removal of aerobic bacteria and fungi from the digestive tract to increase the body's resistance to infectious agents. Selective decontamination is carried out by prescribing for oral administration low-absorbable chemotherapy drugs that suppress the aerobic part of the microflora and do not affect anaerobes.

10. What microorganisms - aerobic or anaerobic - are removed from the biotope during selective decontamination?

Selective decontamination removes aerobic microorganisms.

11. What is eubiosis?

Eubiosis (eumicrobiosis) is a set of microbial populations (microbiocenoses) inhabiting the natural biotopes of a healthy person.

12. What changes occur during dysbiosis?

Dysbiosis is characterized by deviations in the composition of the microbiocenosis, significantly beyond the limits physiological norm. As a result, the protective and other beneficial functions of normal microflora are disrupted, and there is a threat of the development of local and general pathological processes.

Dysbiosis is classified according to etiology (fungal, staphylococcal, Proteus, etc.) and localization (dysbiosis of the mouth, intestines, vagina, etc.). Changes in the composition and functions of normal microflora are accompanied by various disorders: the development of infections, diarrhea, constipation, malabsorption syndrome, gastritis, colitis, peptic ulcers, malignant neoplasms, allergies, urolithiasis, hypo- and hypercholesterolemia, hypo- and hypertension, caries, arthritis, liver damage, etc.

1. Normal microflora accompanies its owner throughout his life. Its significant importance in maintaining the vital functions of the body is evidenced by observations of gnotobiont animals (devoid of their own microflora), whose life differs significantly from that of normal individuals, and sometimes is simply impossible. In this regard, the study of normal human microflora and its disorders is a very significant section of medical microbiology.
Currently, it is firmly established that the human body and the microorganisms inhabiting it are a single ecosystem.
From a modern point of view, normal microflora should be considered as a collection of many microbiocenoses, characterized by a certain species composition and occupying one or another biotype in the body.
In any microbiocenosis one should distinguish:
indigenous, autochthonous flora - characteristic, constantly occurring types of microorganisms. Their number is relatively small, but numerically they are always represented most abundantly;
allochthonous flora - transient, additional and random. The species composition of such microorganisms is diverse, but they are few in number.
The surfaces of the skin and mucous membranes of the human body are abundantly populated with bacteria. At the same time, the number of bacteria inhabiting integumentary tissues(skin, mucous membranes), many times exceeds the number of the host’s own cells. Quantitative fluctuations of bacteria in a biocenosis can reach several orders of magnitude for some bacteria and nevertheless fall within the accepted standards. The formed microbiocenosis exists as a single whole. as a community of species united by food chains and related by microecology.
The totality of microbial biocenoses found in the body of healthy people constitutes the normal human microflora.
Currently, normal microflora is considered as an independent extracorporeal organ. It has a characteristic anatomical structure- biofilm, and it has certain functions.
It has been established that normal microflora has a fairly high species and individual specificity and stability.
2. The normal microflora of individual biotopes is different, but is subject to a number of basic patterns:
it is quite stable;
forms a biofilm;
represented by several species, among which dominant species and filler species are distinguished;
Anaerobic bacteria are predominant.
Normal microflora is characterized anatomical features- each ecological niche has its own species composition.
Some biotopes are stable in composition, while others (transient microflora) are constantly changing depending on external factors.
Microorganisms that make up the normal microflora form a clear morphological structure - a biofilm, the thickness of which ranges from 0.1 to 0.5 mm.
Biofilm is a polysaccharide framework consisting of microbial polysaccharides and mucin, which is produced by the cells of the macroorganism. In this framework, microcolonies of bacteria are immobilized - representatives of normal microflora, which can be located in several layers.
The normal microflora includes both anaerobic and aerobic bacteria, the ratio of which in most biocenoses is 10: 1-100: 1.
The colonization of various areas of the body by bacteria begins at the moment a person is born and continues throughout his life.
The formation of the qualitative and quantitative composition of normal microflora is regulated by complex antagonistic and synergistic relationships between its individual representatives within biocenoses.
The composition of transient microflora may vary depending on:
from age;
environmental conditions;
working conditions, diet;
past diseases;
injuries and stressful situations.
The normal microflora includes:
permanent, or resident microflora - is represented by a relatively stable composition of microorganisms, usually found in certain places of the human body in people of a certain age;
transient, or temporary microflora - enters the skin or mucous membranes from the environment, without causing diseases and not permanently living on
surfaces of the human body. It is represented by saprophytic opportunistic microorganisms that live on the skin or mucous membranes for several hours, days or weeks. The presence of transient microflora is determined not only by the supply of microorganisms from the environment, but also by the state of the host’s immune system and the composition of the permanent normal microflora.
Normally, many tissues and organs of a healthy person are free of microorganisms, i.e., sterile. These include:
internal organs;
head and spinal cord;
alveoli of the lungs;
inner and middle ear;
blood, lymph, cerebrospinal fluid;
uterus, kidneys, ureters and urine in the bladder.
This is ensured by the presence of nonspecific cellular and humoral immunity factors that prevent the penetration of microbes into these tissues and organs.
On all open surfaces and in all open cavities, a fairly stable microflora is formed, specific for of this body, biotope or part of it - epitope. The richest in microorganisms:
oral cavity;
colon;
upper sections respiratory system;
external sections genitourinary system;
skin, especially the scalp.

Microflora of the oral cavity.
The uniqueness and peculiarity of the oral cavity is that, firstly, two vital functions are carried out through it and with its help. important functions the human body - breathing and nutrition, and secondly, the fact that it is constantly in contact with the external environment. The mechanisms functioning in the oral cavity are under constant double influence - the influence of the body on the one hand, and the external environment on the other.
Thus, a necessary condition A correct assessment of the detected changes is a very clear idea of ​​the “norm”, that is, those parameters of the functional mechanisms of the oral cavity that do not depend on pathological processes, but are explained by the geno- and phenotypic characteristics of the organism. One of the most informative indicators is the microflora of the oral cavity.
The oral cavity, its mucous membrane and lymphoid apparatus play a unique role in the interaction of the body with the world of microbes around it, between which complex and contradictory relationships have formed in the process of evolution. Therefore, the role of microorganisms is far from clear: on the one hand, they participate in the digestion of food and have a great positive impact on immune system, being powerful antagonists pathogenic flora; on the other hand, they are the causative agents and main culprits of major dental diseases.

There are more different types of bacteria in the oral cavity than in other parts of the gastrointestinal tract, and this number, according to various authors, ranges from 160 to 300 species. This is explained not only by the fact that bacteria enter the oral cavity with air, water, food - the so-called transit microorganisms, the residence time of which is limited. Here we are talking about resident (permanent) microflora, forming a rather complex and stable ecosystem of the oral cavity. These include almost 30 microbial species. IN normal conditions(antiseptic pastes, antibiotics, etc. are not used) changes in the existing ecosystem occur depending on the time of day, year, etc. and only in one direction, i.e., only the number of representatives of different microorganisms changes. However, the species representation remains constant for a particular individual throughout, if not his entire life, then over a long period. The composition of the microflora depends on salivation, the consistency and nature of food, as well as on the hygienic maintenance of the oral cavity, the condition of the tissues and organs of the oral cavity and the presence of somatic diseases.
Disorders of salivation, chewing and swallowing always lead to an increase in the number of microorganisms in the oral cavity. Various anomalies and defects that make it difficult to wash out microorganisms with saliva (carious lesions, low-quality dentures, etc.) contribute to an increase in their number in the oral cavity.
The microflora of the oral cavity is extremely diverse and includes bacteria (spirochetes, rickettsia, cocci, etc.), fungi (including actinomycetes), protozoa, and viruses. At the same time, a significant part of the microorganisms in the oral cavity of adults are anaerobic species. According to various authors, the content of bacteria in oral fluid ranges from 43 million to 5.5 billion in 1 ml. The microbial concentration in dental plaques and gingival sulcus is 100 times higher - approximately 200 billion microbial cells in 1 g of sample (which contains about 80% water).

Most large group The bacteria that permanently reside in the oral cavity are cocci - 85 - 90% of all species. They have significant biochemical activity, decompose carbohydrates, break down proteins with the formation of hydrogen sulfide.
Streptococci are the main inhabitants of the oral cavity. 1 ml of saliva contains up to 109 streptococci. Most streptococci are facultative (non-strict) anaerobes, but obligate (strict) anaerobes - peptococci - are also found. Streptococci ferment carbohydrates according to the type of lactic acid fermentation with the formation of significant amounts of lactic acid and other organic acids. Acids formed as a result of the activity of streptococci inhibit the growth of certain putrefactive microorganisms, staphylococci, coli, typhoid and dysentery bacilli entering the oral cavity from the external environment.
Staphylococci - Staph. - are also present in dental plaque and on the gums of healthy people. epidermidis, but some people may also have Staph. aureus.
Rod-shaped lactobacilli constantly live in certain quantities in healthy cavity mouth Like streptococci, they produce lactic acid, which inhibits the growth of putrefactive and some other microorganisms (staphylococci, E. colli, typhoid and dysentery bacilli). The number of lactobacilli in the oral cavity increases significantly with dental caries. To assess the “activity” of the carious process, a “lactobacillentest” (determining the number of lactobacilli) has been proposed.
Leptotrichia also belong to the family of lactic acid bacteria and are causative agents of homofermentative lactic acid fermentation. Leptotrichia are strict anaerobes.
Actinomycetes (or radiant fungi) are almost always present in the oral cavity of a healthy person. Outwardly, they are similar to filamentous mushrooms: they consist of thin, branching threads - hyphae, which, intertwining, form mycelium visible to the eye.
Yeast-like fungi of the genus Candida (C. albicans, C. tropicalis, C. crusei) are found in the oral cavity of healthy people in 40 - 50% of cases. Pathogenic properties are most pronounced in C. albicans. Yeast-like fungi, multiplying intensively, can cause dysbiosis, candidiasis or local damage to the oral cavity (thrush) in the body. These diseases arise as a result of uncontrolled self-medication with antibiotics. wide range actions or strong antiseptics when fungal antagonists from representatives of normal microflora are suppressed and the growth of yeast-like fungi resistant to most antibiotics is enhanced (antagonists are some representatives of microflora that suppress the growth of other representatives) .
Spirochetes populate the oral cavity from the moment a child's baby teeth erupt and from that time on become permanent inhabitants of the oral cavity. Spirochetes cause pathological processes in association with fusobacteria and vibrios ( ulcerative stomatitis, Vincent's angina). Many spirochetes are found in periodontal pockets during periodontitis, in carious cavities and dead pulp.
Half of healthy people can harbor protozoa in their mouths, namely Entamoeba gingivalis and Trihomonas. The largest number of them is found in dental plaque, purulent contents of periodontal pockets, periodontitis, gingivitis, etc. They multiply intensively due to unhygienic maintenance of the oral cavity.
The normal microflora of the oral cavity is quite resistant to the action of antibacterial factors in the oral fluid. At the same time, it itself participates in protecting our body from microorganisms coming from outside (its own normal microflora suppresses the growth and reproduction of pathogenic “strangers”). The antibacterial activity of saliva and the number of microorganisms living in the oral cavity are in a state dynamic balance. The main function of the antibacterial system of saliva is not to completely suppress the microflora in the oral cavity, but to control its quantitative and qualitative composition.

When isolating microorganisms from different areas of the oral cavity of adults, a predominance of certain species in different areas was noted. If we divide the oral cavity into several biotopes, the following picture will appear. The mucous membrane, due to its vastness, has the most variable composition of microflora: gram-negative anaerobic flora and streptococci are predominantly isolated on the surface. In the sublingual folds and crypts of the mucosa, obligate anaerobes predominate. Streptococci and corynebacteria are found in the mucosa of the hard and soft palate.

The second biotope is the gingival groove (groove) and the liquid contained in it. There are bacteroids (B. melaninogenicus), porphyromonas (Porphyromonas gingivalis), Prevotella intermedia, as well as actinobacillus actinomycetemcomitans, yeast-like fungi and mycoplasmas, as well as neisseria, etc.

The third biotope is dental plaque - this is the most massive and diverse bacterial accumulation. The number of microorganisms ranges from 100 to 300 million per 1 mg. The species composition is represented by almost all microorganisms with a predominance of streptococci.

Oral fluid should be named as the fourth biotope. Through it, the relationship between all other biotopes and the organism as a whole is realized. Significant quantities of oral fluid contain veillonella, streptococci (Str. salivarius, Str. mutans, Str. mitis), actinomycetes, bacteroides, and filamentous bacteria.

Thus, the oral microflora is normally represented various types microorganisms. Some of them are associated with diseases such as caries and periodontitis. Microorganisms are involved in the occurrence of these most common ailments. As experimental studies conducted on animals have shown, for the development of caries, the presence of microorganisms is essential (Orland, Blaynay, 1954; Fitzgerald, 1968.) Introduction to oral cavity streptococci in sterile animals leads to the formation of typical dental caries (FFitzgerald, Keyes, 1960; Zinner, 1967). However, not all streptococci are equally capable of causing caries. It has been proven that Streptococcus mutans, whose colonies make up up to 70% of all dental plaque microorganisms, has an increased ability to form dental plaque and cause dental damage.

For the development of inflammatory periodontal diseases, the main condition is also the presence of an association of microorganisms, such as Actinibacillus actinonomicitemcomitans, Porphyromonaas gingivalis, Prevotella intermedia, as well as streptococci, bacteroides, etc. Moreover, the occurrence and intensity of pathological processes directly depends on the qualitative and quantitative composition of the microflora of dental plaque and plaques (see table).

As follows from the above facts, caries and inflammatory diseases of the oral cavity occur when the normal balance between one’s own and foreign microflora is disturbed. Therefore, hygiene products with antibacterial components should be aimed at maintaining the constancy of the microflora at the physiological level, i.e., when there is no shift in the quantitative and qualitative composition of microorganisms in favor of pathogenic ones throughout the entire period of the body’s life.