Infection, definition of the concept. Conditions for the occurrence of an infectious process. Main features of infectious diseases. Classifications of infectious diseases. Infection and infectious disease

“Infectious process” is a phrase that has not surprised anyone for many years. Diseases of this group accompany humanity throughout its existence. To better understand how to protect yourself from infection, you need to take a closer look this concept and its features.

general information

First, you will become familiar with the main terms. So, an infection is not a disease yet. It represents only the moment of infection. It covers the entry of the pathogen into the body and the beginning of its development.

The infectious process is the state in which you are after infection. That is, it is a kind of reaction of the body to those pathogenic bacteria that have begun to multiply and inhibit the functioning of the systems. He is trying to free himself from them, to restore his functions.

An infectious process and an infectious disease are almost the same concepts. However, the latter term implies the manifestation of the body's condition in the form of symptoms and signs. In most cases, the disease ends with recovery and complete destruction of harmful bacteria.

Signs of IP

The infectious process has certain features that distinguish it from other pathological phenomena. Among them are the following:

1. High degree of infectiousness. Every sick person becomes a source of pathogens for other people.

1. Air. Most often, pathogens enter the respiratory system, where they begin to multiply. They are transmitted to another person when talking, sneezing, and even penetrate into the body with dust.

2. Fecal-oral. The place of localization for such microorganisms is the stomach and intestines. Microbes enter the body through food or water.

3. Contact. Such diseases often affect the skin and mucous membrane. Hand over pathogenic microflora in this case, you can touch healthy person or when using contaminated items.

4. Transmissive. It involves the localization of harmful microorganisms in the blood. In this case, the infection is transmitted by insects, such as mosquitoes.

5. Transplacental. This route involves the passage of germs and bacteria from mother to child through the placenta.

6. Artificial. In this case, the infection is introduced into the body as a result of any manipulation: in a hospital, tattoo parlor, beauty salon and other establishments.

7. Sexual, that is, through sexual contact.

As you can see, if you follow the rules of hygiene, you can avoid many problems.

What is a “hidden infection”?

It must be said that pathology may not always manifest itself. The infection can live in the human body for a very long time without making itself felt. These are the so-called “hidden infections”. Most often they are transmitted sexually. The first symptoms may appear only after a week. During this time, microorganisms already cause serious harm to all human systems.

Such infections include: chlamydia, syphilis, gonorrhea, trichomoniasis. In addition, herpes, papillomaviruses, and cytomegalovirus can also be included here. A person can live without even knowing that these problems exist. Often pathology can be detected only with the help of special tests. Hidden infections They are very insidious, so you should take care of yourself and try not to become infected with them.

Features of treatment of the disease

There are several stages of therapy:

1. Impact on the pathogen using antibacterial, antiviral, antifungal drugs and antibiotics.

2. Prevention of further development of the process. This is done with the help of detoxification therapy, taking anti-inflammatory drugs, immunomodulators, and multivitamins.

3. Elimination of symptoms.

Flow infectious process can be very severe, so you cannot always do without medical help.

Prevention

Taking precautions will not only help you stay healthy and happy, but will also protect you from possible serious complications. Prevention is quite simple:

1. Proper nutrition And active image life.

2. Refusal bad habits: smoking, drinking alcohol.

3. Maintaining an orderly sex life.

4. Protecting the body with the help of special medications during the height of the infection.

5. Constant implementation of all necessary hygiene procedures.

6. Timely contact a doctor in case of any problems.

That's all the features of the infectious process. Be healthy and take care of yourself.

The environment is filled with a huge number of “inhabitants”, among which there are various microorganisms: viruses, bacteria, fungi, protozoa. They can live in absolute harmony with humans (non-pathogenic), exist in the body without causing harm normal conditions, but become more active under the influence of certain factors (conditionally pathogenic) and be dangerous to humans, causing the development of a disease (pathogenic). All these concepts relate to the development of the infectious process. What is an infection, what are its types and features - is discussed in the article.

Basic Concepts

An infection is a complex of relationships various organisms, which has a wide range of manifestations - from asymptomatic carriage to the development of the disease. The process appears as a result of the introduction of a microorganism (virus, fungus, bacteria) into a living macroorganism, in response to which a specific protective reaction occurs on the part of the host.

Features of the infectious process:

1. Contagiousness is the ability to quickly spread from a sick person to a healthy person.
2. Specificity - a certain microorganism causes a specific disease, which has characteristic manifestations and localization in cells or tissues.
3. Periodicity - each infectious process has periods of its course.

Periods

The concept of infection is also based on cyclicity pathological process. The presence of periods in development is characteristic of each similar manifestation:

1. The incubation period is the time that passes from the moment the microorganism is introduced into the body of a living being until the first clinical signs of the disease appear. This period can last from several hours to several years.
2. The prodrome period is the appearance of a general clinic characteristic of most pathological processes ( headache, weakness, fatigue).
3. Acute manifestations are the peak of the disease. During this period, specific symptoms of infection develop in the form of rashes, characteristic temperature curves, and tissue damage at the local level.
4. Convalescence is the time of fading of the clinical picture and recovery of the patient.

Types of infectious processes

To consider in more detail the question of what an infection is, you need to understand what it is like. There are a significant number of classifications depending on the origin, course, localization, number of microbial strains, etc.

1. According to the method of penetration of pathogens:

• exogenous process - characterized by penetration pathogenic microorganism from external environment;
• endogenous process - activation of one’s own opportunistic microflora occurs under the influence of unfavorable factors.

2. By origin:

• spontaneous process - characterized by the absence of human intervention;
• experimental - the infection was bred artificially in a laboratory.

3. By the number of microorganisms:

• monoinfection - caused by one type of pathogen;
• mixed - several types of pathogens are involved.

4. By order:

• primary process - a newly emerging disease;
• secondary process - accompanied by the addition of additional infectious pathology against the background of the primary disease.

5. By localization:

• local form - the microorganism is found only in the place through which it entered the host’s body;
• generalized form - pathogens spread throughout the body with further settling in certain favorite places.

6. Downstream:

• acute infection - has a clear clinical picture and lasts no more than a few weeks;
• chronic infection - characterized by a sluggish course, can last for decades, has exacerbations (relapses).

7. By age:

• “childhood” infections - affect children mainly aged 2 to 10 years ( chicken pox, diphtheria, scarlet fever, whooping cough);
• There is no concept of “adult infections” as such, since the child’s body is just as sensitive to those pathogens that cause the development of the disease in adults.

There are concepts of reinfection and superinfection. In the first case, a person who has fully recovered, after an illness, becomes infected again with the same pathogen. In case of superinfection reinfection occurs during the course of the disease (strains of the pathogen are layered on top of each other).

Paths of entry

There are the following routes of penetration of microorganisms that ensure the transfer of pathogens from the external environment to the host organism:

• fecal-oral (consists of nutritional, water and contact-household);
• transmissible (blood) - includes sexual, parenteral and through insect bites;
• aerogenic (airborne dust and airborne droplets);
• contact-genital, contact-wound.

Most pathogens are characterized by the presence of a specific route of penetration into the macroorganism. If the transmission mechanism is interrupted, the disease may not appear at all or may worsen in its manifestations.

Localization of the infectious process

Depending on the area affected, the following types of infections are distinguished:

1. Intestinal. The pathological process occurs in the departments gastrointestinal tract, the pathogen enters through the fecal-oral route. These include salmonellosis, dysentery, rotavirus, and typhoid fever.
2. Respiratory. The process occurs in the upper and lower respiratory tract, microorganisms “move” in most cases through the air (influenza, adenoviral infection, parainfluenza).
3. External. Pathogens contaminate the mucous membranes and skin, causing fungal infections, scabies, microsporia, and STDs.
4. Bloody. The infection enters through the blood, spreading further throughout the body (HIV infection, hepatitis, diseases associated with insect bites).

Intestinal infections

Let us consider the features of pathological processes using the example of one of the groups - intestinal infections. What is an infection that affects the human gastrointestinal tract, and what is its difference?

Diseases of this group can be caused by pathogens of bacterial, fungal and viral origin. Viral microorganisms that can penetrate various departments intestinal tract, rotaviruses and enteroviruses are considered. They can spread not only by the fecal-oral route, but also by airborne droplets, affecting the epithelium of the upper respiratory tract and causing herpes sore throat.

Bacterial diseases (salmonellosis, dysentery) are transmitted exclusively by the fecal-oral route. Infections of fungal origin occur in response to internal changes in the body that occur under the influence of long-term use antibacterial or hormonal drugs, for immunodeficiency.

Rotaviruses

Rotavirus intestinal infection, the treatment of which must be comprehensive and timely, in principle, like any other disease, is half clinical cases viral intestinal infectious pathologies. An infected person is considered dangerous to society from the end of the incubation period until complete recovery.

Rotavirus intestinal infection in children is much more severe than in adults. Stage acute manifestations accompanied by the following clinical picture:

• abdominal pain;
• diarrhea (the stool is light in color and may contain blood);
• bouts of vomiting;
• hyperthermia;
• runny nose;
• inflammatory processes in the throat.

Rotavirus intestinal infection in children in most cases is accompanied by outbreaks of the disease in schools and preschool institutions. By the age of 5, most children have experienced the effects of rotaviruses. Subsequent infections are not as severe as the first clinical case.

Surgical infection

Most patients in need of surgical intervention, are interested in the question of what a surgical-type infection is. This is the same process of interaction between the human body and a pathogenic pathogen, only occurring during surgery or requiring surgical intervention to restore functions in a certain disease.

There are acute (purulent, putrefactive, specific, anaerobic) and chronic process(specific, non-specific).

Depending on location surgical infection diseases are identified:

• soft tissues;
• joints and bones;
• brain and its structures;
• abdominal organs;
• organs of the chest cavity;
• pelvic organs;
• individual elements or organs (breast, hand, foot, etc.).

Pathogens of surgical infection

Currently, the most frequent “guests” of acute purulent processes are:

• staphylococcus;
• Pseudomonas aeruginosa;
• enterococcus;
• coli;
• streptococcus;
• Proteus.

The entrance gates for their penetration are various damage to the mucous membranes and skin, abrasions, bites, scratches, ducts of the glands (sweat and sebaceous). If a person has chronic foci of accumulation of microorganisms ( chronic tonsillitis, rhinitis, caries), then they cause the spread of pathogens throughout the body.

Treatment of infection

The basis for getting rid of pathological microflora is etiotropic therapy aimed at eliminating the cause of the disease. Depending on the type of pathogen, the following groups of medications are used:

1. Antibiotics (if the causative agent is a bacterium). The choice of a group of antibacterial agents and a specific drug is made on the basis of bacteriological examination and determination of the individual sensitivity of the microorganism.
2. Antiviral (if the causative agent is a virus). At the same time, drugs are used that strengthen the human body’s defenses.
3. Antimycotic agents (if the pathogen is a fungus).
4. Antihelminthic (if the pathogen is a helminth or a protozoan).

Treatment of infections in children under 2 years of age is carried out in a hospital setting to avoid the development of possible complications.

Conclusion

After the occurrence of a disease that has a specific pathogen, the specialist differentiates and determines the need for hospitalization of the patient. The specific name of the disease must be indicated in the diagnosis, and not just the word “infection”. Medical history that is taken for inpatient treatment, contains all the data on the stages of diagnosis and treatment of a specific infectious process. If there is no need to hospitalize the patient, all such information is recorded in the outpatient card.

Infection

This term has other meanings, see Infection (meanings).

In 1546, Girolamo Fracastoro introduced the term “infection” into medicine.

The science of infection is called infectology. This is the science that studies the infectious process, infectious disease, infectious pathology, which arises as a result of the competitive interaction of the body with pathogenic or opportunistic pathogens (infectogens), and develops methods for the diagnosis, treatment and prevention of infectious diseases. Infectology as a systemic medical science is connected or affects in one way or another all other branches of medicine.

Damages of organs and systems (infectious and inflammatory processes: - ites) caused by infectology - often should be differentiated from other disciplines - systemic. as it progresses - with toxicology, oncology, hematology (secondary immunodeficiencies in radiation sickness, leukemia, with damage to the thymus, spleen and bone marrow, with vitamin deficiency: berry berry, pellagra, night blindness) and endocrinology (secondary infectious complications in diabetes mellitus, hypothyroidism), metabolic syndromes- such as uremia, liver failure, liver cirrhosis, multiple organ failure.

General infectology is often differentiated from general diseases and local inflammatory processes (angina, otitis, sinusitis) from purulent-septic surgery (Phlegmon, Empyema, abscesses) and gangreous-necrotic surgery (pulmonary gangrene/pneumonia, decurable ulcer) which they give.

Conditions, pathologies and diseases, and infectious and inflammatory processes are often differentiated by toxic processes, pathologies and conditions (Methods of detoxification and detoxification of the body often overlap), with hematological (Hematogenous immunodeficiencies, aplastic anemia, infectious complications in hemablastosis), with diseases caused by disorders metabolism, with endocrine (metabolic diarrhea with pancreatogenic fermentopathies, uremic enteritis, secondary metabolic immunodeficiencies against the background of renal, liver failure, against the background of diabetes mellitus and their infectious complications, vitamin deficiency: scurvy) and oncology (the last variant of differential diagnosis is the most often difficult to implement task in modern medicine, however, these mistakes can cost the patient's life).

Most often, gastrointestinal forms of acute infections should be differentiated from abdominal or coloproctorectal in the form acute poisoning and intoxications of infectious origin should be differentiated from intoxications of non-infectious origin - toxic (with food poisoning, botulism, infectious-toxic shock), oncological (due to the similarity in the tendency to metastasize some infectious pathogens and their ability to give tumor-like symptoms), and in some, paraneoplastic, carcinogenic processes, and various and metabolic syndromes.

bacterial - bacteriology, specific: phthisiology and venereology. Epidemiology was one of the areas of infectology and in its classical form was associated with it,

dealing with issues of the area of ​​the epidemic process - issues of the spread of infectious pathogens. Microbiology deals with the study of the pathogenic properties of living organisms. Hygiene, antiseptics, asepsis and vaccination deal with issues of measures to prevent and contain the spread of infectious diseases and the formation of pandemics in endemic, and more often, in the era of globalization, climate collapse and global warming, in non-endemic regions.

Types of infections

The infection can develop in different directions and take various shapes. The form of infection development depends on the ratio of the pathogenicity of the microorganism, the factors protecting the macroorganism from infection and environmental factors.

Generalized infection- an infection in which pathogens spread predominantly through the lympho-hematogenous route throughout the entire macroorganism.

Local infection- local damage to body tissues under the influence of pathogenic factors of an infectious gene. A local process, as a rule, occurs at the site of penetration of the microbe into the tissue and is usually characterized by the development of a local inflammatory reaction. Local infections are represented by sore throats, boils, diphtheria, erysipelas, etc. In some cases, a local infection can develop into a general one. In some cases, a local infection, from an infectious disease specialist, can move into surgical practice or into the hands of specialists, depending on the affected organs and the degree of chronicity of the process (otolaryngologist - tonsillitis, urologist - prostatitis, osteomyelitis, periodontitis - maxillofacial surgeon, lung abscess, gangrene of the lung - thoracic surgeon, rheumatoid arthritis- rheumatologist, meningoencephalitis, gangliitis, arachnoiditis - neurologist, vasculitis - vascular surgeon; nephritis, cystitis, pyelonephritis - nephrologist, pneumonia, bronchitis, pleurisy - pulmonologist, gastroenteritis, hepatitis - gastroenterologist, peritonitis - abdominal surgeon, appendicitis, colitis - coloproctal surgeon)

General infection- penetration of microorganisms into the blood and their spread throughout the body. Having penetrated the tissues of the body, the microbe multiplies at the site of penetration and then penetrates the blood. This development mechanism is typical for influenza, salmonellosis, typhus, syphilis, some forms of tuberculosis, viral hepatitis, etc.

Latent infection- a condition in which a microorganism living and multiplying in the tissues of the body does not cause any symptoms ( chronic form gonorrhea, chronic salmonellosis, etc.).

Intercurrent infection- an infection that occurs secondary to an existing disease, or to an existing disease, for example, diabetes mellitus, or renal-liver failure. It is one type of immunodeficiency.

Manifest infection is an infection with obvious specific clinical signs.

Focal infection

An infection that occurs as a result of inflammation of an organ, accompanied by tissue destruction.

Stages of infectious diseases

Incubation period- [from lat. incubation"Hatching chicks"]. Typically, between the penetration of an infectious agent into the body and the manifestation of clinical signs, there is a period of time specific for each disease - an incubation period, characteristic only for exogenous infections. During this period, the pathogen multiplies, and both the pathogen and the toxins it produces accumulate to a certain threshold value, beyond which the body begins to respond with clinically pronounced reactions. The duration of the incubation period can vary from several hours and days to several years.

Prodromal period- [from ancient Greek. πρόδρομος “running ahead, preceding”]. As a rule, the initial clinical manifestations do not bear any pathognomonic [from ancient Greek. πάθος "disease" + γνώμων "interpreter, caretaker, norm, rule"] for a specific infection of signs. Weakness, headache, and feeling of exhaustion are common. This stage of an infectious disease is called the prodromal period, or “precursor stage.” Its duration does not exceed 24-48 hours.

Period of disease development- during this phase, individual traits of the disease or signs common to many infectious processes (fever, inflammatory changes, etc.) appear. In the clinically expressed phase, one can distinguish the stages of increasing symptoms (stadium incrementum), flourishing of the disease (stadium acme) and fading of manifestations (stadium decrementum).

Convalescence- [from lat. re-, repetition of action, + convalescentia, recovery]. The period of recovery, or convalescence, as the final period of an infectious disease, can be fast (crisis) or slow (lysis), and can also be characterized by a transition to a chronic state. In favorable cases, clinical manifestations usually disappear faster than the normalization of morphological disorders of organs and tissues and complete removal pathogen from the body. Recovery may be complete or accompanied by the development of complications (for example, from the central nervous system, musculoskeletal system, or of cardio-vascular system). The period of final removal of the infectious agent can be delayed and for some infections (for example, typhus) can be decades.

Literature

• Gertsenshtein G. M., Sokolov A. M.,. Infectious diseases // Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg, 1890-1907.
• Borinskaya S. A. Infections as a selection factor // anthropogenez.ru.

31) Characteristic features of infectious diseases.

PECULIARITIES:

1) Specificity - each pathogen causes an infectious disease specific to it, with a specific localization in the organ/tissue.

2) Contagiousness - The ability to be transmitted from an infected person to a non-infected person, i.e. spread rapidly through susceptible populations.

3) Cyclicity of the flow, i.e. availability of periods:

1. Incubation period- the time that passes from the moment of infection to the onset of clinical manifestations diseases. Depending on the properties of the pathogen, immune status macroorganism, the nature of the relationship between the macro- and microorganism, the incubation period can vary from several hours to several months and even years;

2. Prodromal period- time of appearance of the first clinical symptoms general, non-specific for of this disease, for example, weakness, fatigue, lack of appetite, etc.;

3. Period of acute manifestations of the disease- the height of the disease. At this time, symptoms typical for this disease appear: temperature curve, rashes, local lesions, etc.;

4. Convalescence period- a period of fading and disappearance of typical symptoms and clinical recovery.

32 Types of infections -

1) Monoinfection - diseases caused by one type of microorganism.

2) Mixed infections - mixed - develop during infection with several types of microorganisms. Features: more severe course, pathogenicity is not cumulative. Pr - Syphilis+gonorrhea+chlamydia due to sexual infection

Types of mixes: A) If microorganisms activate or aggravate the course of the disease - Activators or Synergists (Influenza virus and group B streptococci)

B) If microorganisms suppress each other - Antagonists (Escherichia coli suppresses the activity of salmonella, shigella, strepto/staphyllococcus).

C) They do not interact at all - indifferent.

3) Superinfections - secondary infections that develop against the background of existing diseases. Re-infection occurs before recovery (Syphilis).

4) Reinfection - re-infection with the same species after recovery. Pr-gonorrhea, syphilis, meningococcal infections, scarlet fever, dysentery, erysipelas.

5) Relapse - infection during the action of a pathogen already present in the body, exacerbation clinical symptoms.

6) The occurrence of an infectious process caused by the activation of the normal flora inhabiting the skin and mucous membranes is referred to as autoinfection.

7) Secondary infection - occurs against the background of a developed primary disease and is caused by another type of pathogen. It can be Exogenous/Endogenous. A) Exogenous: when a pathogen enters the body from outside.

B) Endogenous(oppurtonic) - Caused by representatives of normal microflora when the body’s defenses are reduced. (Escherichiosis, the introduction of intestinal bacteria into the urinary tract.). Important Feature- lack of incubation period. A type of endogenous infection is autoinfection; it occurs as a result of self-infection through the transfer of a pathogen from one biotope to another.

33 .Paths of penetration of microbes into the human body.

Transmission route is a set of transmission factors () that ensure the transfer of a pathogenic agent from a patient, or carrier, to a healthy one.

The transmission mechanism is the way the pathogen moves from the source to the body. Has 3 stages:

1) Removal of the pathogen from the source into the environment.

2) The presence of the pathogen in the environment and its objects (in transmission factors).

3) Penetration of the pathogen into the body.

Depending on the mechanism, the following paths are distinguished:

1) The fecal-oral mechanism has alimentary (through food), water, contact and household transmission routes.

2) Blood (transmissible) - parenteral, sexual, through insect bites.

3) Aerogenic - airborne, airborne and dusty.

4) Contact - wound and contact-genital.

For many pathogens, the transmission route is strictly specific, and if it is disrupted (if Shigella enters the respiratory tract), it can be interrupted and the disease does not occur, or it can further aggravate the disease (entry treponema pallidum into the blood).

The spread of bacteria, viruses and toxins in the patient’s body.

Any infectious disease, regardless of clinical signs and localization of the microbe in the body, is a disease of the whole organism. If pathogenic microbes have penetrated the blood vessels and begin to multiply in the blood, they very quickly penetrate all internal organs and tissues. This form of infection is called septicemia. It is characterized by a rapid and malignant course and often ends fatal. When microbes are in the blood temporarily and do not multiply in it, but through it are only transferred to other sensitive tissues and organs, where they then multiply, the infection is usually called bacteremia. Sometimes microbes, having penetrated the body, remain only in damaged tissue and, as they multiply, they release toxins. The latter, penetrating into the blood, cause general severe poisoning(tetanus, malignant edema). This process is called toxemia. The ways in which pathogenic microbes are excreted from the body are also different: with saliva, sputum, urine, feces, milk, and secretions from the birth canal.

Nosocomial infections

ICD-10

Nosocomial infections(Also hospital, nosocomial) - as defined by WHO, any clinically significant disease of microbial origin that affects a patient as a result of his hospitalization or visit to a medical institution for the purpose of treatment, or within 30 days after discharge from hospital (for example, wound infection), as well as hospital staff due to their activities, regardless of whether symptoms of this disease appear or do not appear while these persons are in the hospital.

An infection is considered nosocomial if it first appears 48 hours or more after hospital stay, provided there are no clinical manifestations of these infections at the time of admission and the possibility of an incubation period has been excluded. In English, such infections are called nosocomial infections, from ancient Greek. νοσοκομείον - hospital (from νόσος - illness, κομέω - I care).

Hospital infections should be distinguished from the related concepts of iatrogenic and opportunistic infections, which are often confused with them.

Iatrogenic infections- infections caused by diagnostic or therapeutic procedures.

Opportunistic infections- infections that develop in patients with damaged immune defense mechanisms.

Story

From the time the first maternity hospital was established in the 17th century until the middle of the 19th century, puerperal fever was rampant in European maternity hospitals, during epidemics of which the mortality rate carried to the grave up to 27% of women in labor. It was possible to cope with puerperal fever only after its infectious etiology was established and aseptic and antiseptic methods were introduced in obstetrics.

Examples of hospital-acquired infections

• Ventilator-associated pneumonia (VAP)
• Tuberculosis
• Urinary tract infections
• Hospital pneumonia
• Gastroenteritis
• Staphylococcus aureus
• Methicillin-resistant Staphylococcus aureus(MRSA)
• Pseudomonas aeruginosa
• Acinetobacter baumannii
• Stenotrophomonas maltophilia
• Vancomycin-resistant enterococci
• Clostridium difficile

Epidemiology

In the United States, the Centers for Disease Control and Prevention estimates that approximately 1.7 million hospital-acquired infections caused by all types of microorganisms cause or are associated with 99,000 deaths annually.

In Europe, according to the results of hospital studies, mortality from nosocomial infections is 25,000 cases per year, of which two thirds are caused by gram-negative microorganisms.

In Russia, about 30 thousand cases are officially recorded annually, which indicates shortcomings in statistics. A study conducted in 32 emergency hospitals across the country found that hospital-acquired infections developed in 7.6 percent of patients treated in hospitals. If we consider that the approximate number of patients treated in hospitals in Russia is 31-32 million patients, then we should have 2 million 300 thousand cases of hospital infections per year.

Nosocomial agents can cause severe pneumonia, infections of the urinary tract, blood and other organs.

Nosocomial infections are characterized by their own epidemiological features that distinguish them from classical infections. These include: the uniqueness of the mechanisms and factors of transmission, the peculiarities of the course of epidemiological and infectious processes, the important role of medical personnel of healthcare facilities in the emergence, maintenance and spread of nosocomial infections.

Many types of infections are difficult to treat due to antibiotic resistance, which is gradually beginning to spread among gram-negative bacteria, which are dangerous for people in the community environment.

For an HAI to occur, the following must be present: links infectious process:

• source of infection (owner, patient, healthcare worker);
• pathogen (microorganism);
• transmission factors
• susceptible organism

Sources in most cases they serve:

• medical personnel;
• carriers of latent forms of infection;
• patients with acute, advanced or chronic forms of infectious diseases, including wound infections;

Visitors to hospitals are very rarely sources of nosocomial infections.

Transmission factors The most common sources are dust, water, food, equipment and medical instruments.

Leading ways of infection in the conditions of health-care facilities are contact-household, airborne and airborne-dust. The parenteral route is also possible (typical for hepatitis B, C, D, etc.)

Mechanisms of transmission : aerosol, fecal-oral, contact, hemocontact.

Contributing Factors

Surgical bed in Sudan hospital

Factors in the hospital environment that contribute to the spread of nosocomial infections include:

• underestimation of the epidemic danger of nosocomial sources of infection and the risk of infection through contact with a patient;
• LPO overload;
• the presence of undetected carriers of nosocomial strains among medical staff and patients;
• violation by medical staff of the rules of asepsis and antiseptics, personal hygiene;
• untimely implementation of current and final disinfection, violation of the cleaning regime;
• insufficient equipment of health care facilities with disinfectants;
• violation of the disinfection and sterilization regime for medical instruments, devices, devices, etc.;
• outdated equipment;
• unsatisfactory condition of catering facilities and water supply;
• lack of filtration ventilation.

Risk group

Persons at increased risk of infection with nosocomial infections:

1. Sick:
   • without a fixed place of residence, migrating population,
   • with long-term untreated chronic somatic and infectious diseases,
   • unable to receive special medical care;
2. Persons who:
   • therapy that suppresses the immune system (irradiation, immunosuppressants) is prescribed;
   • extensive surgical interventions are carried out followed by blood replacement therapy, program hemodialysis, infusion therapy;
3. Women in labor and newborns, especially premature and post-term;
4. Children with congenital anomalies development, birth trauma;
5. LPO medical staff.

Etiology

In total, there are more than 200 agents that can cause nosocomial infections. Before the advent of antibiotics, the main ones were streptococci and anaerobic bacilli. However, after the start clinical application antibiotics, the causative agents of the main nosocomial infections were previously non-pathogenic (or opportunistic) microorganisms: St. aureus, St. epidermidis, St. saprophiticus, Escherichia coli, Enterococcus faecalis, Enterococcus durans, Klebsiella sp., Proteus mirabilis, Providencia spp, Acinetobacter, Citrobacter, Serratia marcescens.

It has also been established that nosocomial infection can be associated with the spread of rotavirus, cytomegalovirus infection, campylobacter, hepatitis B, C and D viruses, as well as HIV infection.

As a result of the circulation of microorganisms in the department, their natural selection and mutation occurs with the formation of the most resistant hospital strain, which is the direct cause of nosocomial infections.

Hospital strain - this is a microorganism that has changed as a result of circulation in the department in its genetic properties, as a result of mutations or gene transfer (plasmids) and has acquired some unusual characteristics of the “wild” strain character traits allowing him to survive in a hospital setting.

The main features of the adaptation are resistance to one or more broad-spectrum antibiotics, resistance to environmental conditions, decreased sensitivity to antiseptics. Hospital strains are very diverse; each hospital or department may have its own characteristic strain with a unique set of biological properties.

Classification

1. Depending on the routes and factors of transmission, nosocomial infections are classified:
   • Airborne (aerosol)
   • Introductory nutritional
   • Contact and household
   • Contact-instrumental
   • Post-injection
   • Postoperative
   • Postpartum
   • Post-transfusion
   • Postendoscopic
   • Post-transplant
   • Postdialysis
   • Post-hemosorption
   • Post-traumatic infections
   • Other forms.
2. From the nature and duration of the flow:
   • Acute
   • Subacute
   • Chronic.
3. By severity:
   • Heavy
   • Medium-heavy
   • Mild forms of clinical course.
4. Depending on the extent of the infection:
   • Generalized infections: bacteremia (viremia, mycemia), septicemia, septicopyemia, toxic-septic infection (bacterial shock, etc.).
   • Localized infections
   • Skin infections and subcutaneous tissue(burn, operating, traumatic wounds, post-injection abscesses, omphalitis, erysipelas, pyoderma, abscess and phlegmon of the subcutaneous tissue, paraproctitis, mastitis, dermatomycosis, etc.);
   • Respiratory infections (bronchitis, pneumonia, pulmonary abscess and gangrene, pleurisy, empyema, etc.);
   • Eye infections (conjunctivitis, keratitis, blepharitis, etc.);
   • ENT infections (otitis, sinusitis, rhinitis, mastoiditis, tonsillitis, laryngitis, pharyngitis, epiglottitis, etc.);
   • Dental infections (stomatitis, abscess, etc.);
   • Infections of the digestive system (gastroenterocolitis, enteritis, colitis, cholecystitis, hepatitis, peritonitis, peritoneal abscesses, etc.);
   • Urological infections (bacteriuria, pyelonephritis, cystitis, urethritis, etc.);
   • Infections of the reproductive system (salpingoophoritis, endometritis, etc.);
   • Bone and joint infections (osteomyelitis, joint infection or joint capsule, intervertebral disc infection);
   • Infections of the central nervous system (meningitis, brain abscess, ventriculitis, etc.);
   • Infections of the cardiovascular system (infections of arteries and veins, endocarditis, myocarditis, pericarditis, postoperative mediastinitis).

Prevention

Prevention of nosocomial infections is a complex and comprehensive process that must include three components:

• minimizing the possibility of introducing infection from the outside;
• preventing the spread of infection between patients within the institution;
• preventing the spread of infection outside the health care facility.

Treatment

Treatment of nosocomial infection

Ideally, an antimicrobial drug should be prescribed narrow spectrum activity that acts on a specific microorganism isolated during a microbiological study. However, in practice, nosocomial infection, especially in the first days, is almost always treated empirically. The choice of the optimal antimicrobial therapy regimen depends on the predominant microflora in the department and the spectrum of its antibiotic resistance.

In order to reduce antibiotic resistance of pathogens, regular rotation should be practiced. antibacterial drugs(when certain antibiotics are used in the department for empirical therapy for several months and then replaced by the next group).

Initial antimicrobial therapy

Nosocomial infections caused by gram-positive microorganisms are most effectively treated with vancomycin, while carbapenems (imipenem and meropenem), IV generation cephalosporins (cefepime, cefpirome) and modern aminoglycosides (amikacin) are most active against gram-negative bacteria.

From the above, one should not conclude that nosocomial infection can only be treated with the above remedies. For example, pathogens of urinary tract infections remain highly sensitive to fluoroquinolones, cephalosporins III generation and etc.

But a serious nosocomial infection really requires the prescription of carbapenems or IV generation cephalosporins, since they have the widest spectrum of activity and act on polymicrobial flora, including multidrug-resistant gram-negative pathogens and many gram-positive microorganisms. The disadvantage of both groups of drugs is the lack of activity against methicillin-resistant staphylococci, so in severe cases they have to be combined with vancomycin.

In addition, all of these drugs do not act on fungal pathogens, the role of which in the development of nosocomial infections has increased significantly. Accordingly, in the presence of risk factors (for example, severe immunodeficiency), it should be prescribed antifungal agents(fluconazole, etc.)

Localization

Drugs of choice

In the 90s of the twentieth century it was shown that the effectiveness of the starting antibacterial therapy has a direct impact on the mortality of hospitalized patients. Mortality among patients who received ineffective initial therapy was higher than in patients who were prescribed antibiotics that are active against most pathogens. Moreover, in the case of inadequate initial therapy, even a subsequent change of antibiotic, taking into account microbiological data, did not lead to a decrease in mortality.

Thus, in case of severe nosocomial infections, the very concept of “reserve antibiotic” loses its meaning. The effectiveness of initial therapy is an important factor on which the prognosis for life depends.

Based on these data, it was developed de-escalation therapy concept. Its essence lies in the fact that a combination of antimicrobial agents, acting on all possible infectious agents. For example, carbapenem or cefepime are combined with vancomycin (plus fluconazole) depending on the composition of the likely pathogens.

The point in favor combination therapy serve:

• more wide range activity;
• overcoming resistance, which is more likely to occur when using one drug;
• the presence of theoretical data on the synergism of certain agents.

Before using antibiotics, it is necessary to collect samples of biological fluids for microbiological testing. After receiving the results of microbiological examination and clinical assessment treatment effectiveness after 48-72 hours, therapy correction is possible, for example, discontinuation of vancomycin if a gram-negative pathogen is detected. Theoretically, it is possible to change the entire combination to a drug with a narrower spectrum of action, although in a seriously ill patient who has responded to therapy, any doctor will prefer to leave the prescribed antibiotics.

The possibility of implementing de-escalation therapy depends on efficient work microbiological service and the degree of confidence in its results. If the causative agent remains unknown, then this concept becomes meaningless and can lead to worse treatment results. The appropriateness of de-escalation therapy should be primarily discussed in patients with serious life-threatening infections (eg, ventilator-associated pneumonia, sepsis).

It should be borne in mind that the reverse approach (that is, escalation of therapy) in such situations may result in the death of the patient even before obtaining the result of a microbiological study.

3.Meningococcal infection (definition). Etiology, epidemiology, clinical options.

Meningococcal infection (MI) (Meningitiscerebrospinalisepidemica) - island infectious disease caused by meningococcus, transmitted by airborne droplets and occurring in various clinical options(nasopharyngitis, meningitis, meningococcemia, etc.).

Etiology. The causative agent of the disease is Neisseriameningitidis(Wekselbaum's meningococcus). Gram-negative diplococcus, nonmotile, has no flagella or capsules, does not form spores. Cultivated on media containing human or animal protein, aerobic. Several serotypes (A, B, C, D, X, Y, Z, etc.). Currently, serotypes B and C are more common. The pathogen produces enzymes - hyaluronidase and neuraminidase. The main pathogenicity factor is endotoxin (protein-lipopolysaccharide complex).

Unstable in the environment, dies quickly outside the body (under the influence of direct sunlight, heating, disinfectant solutions, in 70% alcohol). At a temperature of +50° C, meningococcus dies in 5 minutes, at low temperatures (-7...-10° C) - in 2 hours.

Epidemiology. Source of infection: patients and carriers of meningococcus. Greatest danger Patients with localized forms of MI are represented. For one patient with a manifest form of MI, there are up to 2 thousand carriers of meningococcus.

Transmission mechanisms: drip, less often - contact. Basic transmission route - airborne. The pathogen is released from the upper respiratory tract when sneezing, coughing, or crying.

Receptivity to MI universal. Contagiousness index - 10-15%.

Seasonality. An increase in incidence is typical in the winter-spring period.

Immunity has a type-specific character.

Mortality in generalized forms it ranges from 5-6% to 12-14%, and in young children - up to 50%.

Classification of meningococcal infection.

I. Localized forms:

Meningococcal nasopharyngitis;

Carriage of meningococcus.

II. Generalized forms:

Meningococcemia (mild, moderate, severe, hypertoxic);

Purulent meningitis;

Purulent meningoencephalitis;

Combined form (meningitis with meningococcemia, etc.).

III. Rare forms:

Myocarditis;

Osteomyelitis;

Iridocyclitis, etc.

By severity:

1.Light form.

2. Moderate form.

3. Severe form.

4. Hypertoxic (fulminant) form.

Severity criteria:

Severity of intoxication syndrome;

Expression of local changes.

By flow (by character):

1.Smooth.

2.Non-smooth:

With complications;

With a layer of secondary infection;

With exacerbation of chronic diseases.

Clinical picture. Incubation period - from 1-2 to 10 days.

Localized forms. Meningococcal nasopharyngitis (up to 80%). It begins with acute, moderate fever, malaise, and headache. Nasal breathing difficult, scanty nasal discharge, sore throat. Diffuse hyperemia of the mucous membranes and granularity back wall throats. There are no violations of the internal organs. Symptoms of the disease disappear after 7-10 days.

Carriage of meningococcus- culture of meningococcus from nasopharyngeal mucus in the absence of signs of inflammation and increase in titers specific antibodies in the dynamics of the study.

Generalized forms. Meningococcemia(4-10%). Intoxication syndrome and skin damage are pronounced; other organs (joints, kidneys, adrenal glands, spleen) may be involved. It begins suddenly, with a rise in body temperature (up to 39-40° C and above). Headache, malaise, lethargy, refusal to eat, possible vomiting. The main symptom of meningococcemia is a rash. At the beginning, roseolous or roseolopapular elements of various diameters, disappearing with pressure,

located throughout the body (without specific localization). After a few hours, hemorrhagic elements appear: purplish-red in color with a bluish tint, not disappearing with pressure, of varying diameters (from petechiae to ecchymoses), rising above the surface of the skin, dense on palpation, in typical cases - irregular, “star-shaped” shape. The elements fade away after 1-2 days. In the center of large rashes, necrosis > ulcers and the formation of rough scars appear (see Fig. 14). In particularly severe cases, dry gangrene of the fingers and toes may develop, ears, nose. The appearance of a rash in the early stages of the disease on the face, eyelids, and upper body is an unfavorable prognostic sign.

Meningococcal meningitis. It begins acutely with a rise in body temperature to 40°C and above, chills, and severe headache. The headache intensifies with sound and light stimuli, turning the head, and the phenomena of hyperesthesia are pronounced. Repeated vomiting that is not associated with food intake and does not bring relief. Meningeal symptoms. The face is pale, the sclera is injected. Heart sounds are muffled, breathing is frequent and shallow. The cerebrospinal fluid is cloudy, milky white, and flows out under pressure; neutrophilic pleocytosis, slight increase in protein content.

Meningococcal meningoencephalitis. Mainly in young children. Acute onset, febrile body temperature. Encephalic syndrome - motor agitation, convulsions, loss of consciousness, damage to cranial nerves, hemiparesis. Meningeal symptoms are moderate. Often fatal.

Combined form (meningococcal meningitis in combination with meningococcemia). See manifestations above.

Rare forms MI (arthritis, myocarditis, osteomyelitis, iridocyclitis And. etc.) do not have specific clinical symptoms.

Complications. Specific complications life threatening patients - infectious-toxic shock, acute above renal failure, cerebral edema, disseminated intravascular coagulation.

There is no doubt that “infection”, “infectious process” and “infectious disease” are in a certain way associated with pathogenic microbes and at the same time with a macroorganism (human, animal, etc.). It can be noted that pathogenic microbes located in the external environment are not yet an infection, because they can significantly change their metabolism and lose some of the pathogenic factors (spores). The microflora of the human body, which does not cause a pathological process, is also not an infection, and quite mutually beneficial processes often “begin” between it and the body.

The term “infection” in translation means “I infect”, “I pollute” and is more closely associated with pathogenic microorganisms that are not in a dormant state or outside the human body, but in opposition to the macroorganism. Pathogenic microorganisms do not interact with the human body, and both of these sides, being in opposition, try to break each other’s resistance.

Thus, infection is a generalized term indicating microorganisms that exhibit their inherent degree of pathogenicity in a susceptible human body and cause an infectious process, the highest form of manifestation of which is an infectious disease.

This reflects the essence of the infectious process and infectious disease, as well as the factors involved in them. This fully corresponds to the term “source of infection” in relation to patients with an obvious or latent infectious process, who release pathogenic microbes into the external environment that, through a wide variety of contacts, can cause this disease in other susceptible people.

Known different variants infection of people with infectious origin, which is determined by various reasons:

1. Superinfection- layering of repeated infection, which can again cause an infectious disease of identical etiology in a sick person. This option is possible in the absence of immunity (gonorrhea and other infections)

2. Reinfection- layering of repeated infection, which causes an infectious disease of identical etiology in the person who has been ill. The option is similar to the previous one.

3. Secondary infection- layering of a new infection, which causes the patient to develop a disease of a different etiology against the background of a primary infectious disease.

4. Autoinfection- this is one’s own infection (formerly opportunistic, opportunistic microflora), which caused a weakened person (hypothermia, vitamin deficiency, acute and chronic diseases, stress, etc.) infectious disease.

5. Mixed infections- these are polyinfections that cause a polyetiological infectious disease in a susceptible person.

6. Monoinfection– an infection of one species that causes in a susceptible person a monoinfectious disease characteristic of that species.

By origin, the infection can be exogenous or endogenous.

Exogenous infection- these are pathogenic microbes that have penetrated into a susceptible organism from the external environment (soil, water, food, toys, hands, air, medicines, etc.), through numerous factors and routes of infection.

Endogenous infection- this is the microflora of the human body, which he normally does not notice, but it can cause certain infectious diseases when the body’s defenses are weakened, the skin and mucous membranes are damaged, etc.

If the name of a disease or type of bacteria is added to the term “infection,” then a more specific infectious agent or causative agent of an infectious disease or group of such diseases will appear, for example, intestinal infection, typhoid infection, etc.

The process of infection entering the body of a susceptible person, in general, can be described as infection, i.e. a process that combines stages referred to as adhesion, colonization and invasion. If pathogenic microorganisms enter environmental objects and contaminate them, then this process is called microbial contamination or contamination.

The infectious process is a complex of multi-level and multi-system internal processes, including pathological ones, occurring in the body in response to the pathogenic effects of infection. The accumulation of internal processes often turns into pathology, which is manifested by manifest (external) signs. This indicates the occurrence of an infectious disease. It happens that internal processes, reflecting the degree of the body’s resistance to infection, do not develop into a manifest form, although the duration of the internal process can be significant (for example, persistence, etc.).

Thus, an infectious disease is a manifest manifestation of an infectious process occurring in the body in response to the pathogenic effects of an infection, which can be exogenous or endogenous in origin.

In connection with the predominant disease of people or animals, the following main groups of infectious diseases are distinguished:

n anthroponotic(mostly people are sick, for example, cholera, typhoid fever, gonorrhea, etc.),

n zoonotic(mainly animals are sick, for example, swine fever, chicken cholera, infectious anemia of horses, etc.),

n anthropozoonotic(people and animals are sick, for example, tularemia, leptospirosis, plague, brucellosis, etc.).

At the same time, such gradations are quite arbitrary, generated by the level of knowledge modern science. For example, shigellosis (dysentery) for a long time were considered an anthroponotic disease, but at present significant data have accumulated on the disease of shigellosis in cows, pigs and other animals and birds with a clinical picture and the isolation of Shigella. Some types of viruses that previously affected monkeys now cause diseases in humans (HIV, Ebola, etc.).

Infection is the penetration and reproduction of a pathogenic microorganism (bacteria, virus, protozoa, fungus) in a macroorganism (plant, fungus, animal, human) that is susceptible to this type of microorganism. A microorganism capable of infection is called an infectious agent or pathogen.

Infection is, first of all, a form of interaction between a microbe and the affected organism. This process is extended over time and occurs only under certain environmental conditions. In an effort to emphasize the temporal extent of the infection, the term “infectious process” is used.

Infectious diseases: what are these diseases and how do they differ from non-infectious diseases

Under favorable environmental conditions, the infectious process takes extreme degree its manifestation, at which certain clinical symptoms appear. This degree of manifestation is called an infectious disease. Infectious pathologies differ from non-infectious pathologies in the following ways:

• The cause of infection is a living microorganism. The microorganism that causes a particular disease is called the causative agent of that disease;
• Infections can be transmitted from an affected organism to a healthy one - this property of infections is called contagiousness;
• Infections have a latent (hidden) period - this means that they do not appear immediately after the pathogen enters the body;
• Infectious pathologies cause immunological changes - they stimulate an immune response, accompanied by a change in the number of immune cells and antibodies, and also become the cause of infectious allergies.

Rice. 1. Assistants of the famous microbiologist Paul Ehrlich with laboratory animals. At the dawn of the development of microbiology, laboratory vivariums kept a large number of species of animals. Nowadays they are often limited to rodents.

Factors of infectious diseases

So, for an infectious disease to occur, three factors are necessary:

1. Pathogen microorganism;
2. The host organism is susceptible to it;
3. The presence of environmental conditions in which the interaction between the pathogen and the host leads to the occurrence of the disease.

Infectious diseases can be caused by opportunistic microorganisms, which are most often representatives of normal microflora and cause disease only when the immune defense is reduced.

Rice. 2. Candida is part of the normal microflora of the oral cavity; they cause disease only under certain conditions.

But pathogenic microbes, while in the body, may not cause disease - in this case they speak of carriage of a pathogenic microorganism. In addition, laboratory animals are not always susceptible to human infections.

For an infectious process to occur, a sufficient number of microorganisms entering the body, which is called an infectious dose, is also important. The susceptibility of the host organism is determined by its biological species, gender, heredity, age, nutritional sufficiency and, most importantly, condition immune system and the presence of concomitant diseases.

Rice. 3. Malarial plasmodium can spread only in those areas where their specific carriers, mosquitoes of the genus Anopheles, live.

Environmental conditions are also important, in which the development of the infectious process is facilitated as much as possible. Some diseases are characterized by seasonality, some microorganisms can only exist in a certain climate, and some require vectors. Recently, conditions have come to the fore social environment: economic status, living and working conditions, level of health care development in the state, religious characteristics.

Infectious process in dynamics

The development of infection begins with the incubation period. During this period, there are no manifestations of the presence of an infectious agent in the body, but infection has already occurred. During this time, the pathogen multiplies to a certain number or releases a threshold amount of toxin. The duration of this period depends on the type of pathogen.

For example, with staphylococcal enteritis (a disease that occurs when eating contaminated food and is characterized by severe intoxication and diarrhea), the incubation period takes from 1 to 6 hours, and with leprosy it can last for decades.

Rice. 4. The incubation period for leprosy can last for years.

In most cases it lasts 2-4 weeks. Most often, the peak of infectivity occurs at the end of the incubation period.

The prodromal period is a period of precursors of the disease - vague, nonspecific symptoms, such as headache, weakness, dizziness, changes in appetite, fever. This period lasts 1-2 days.

Rice. 5. Malaria is characterized by fever, which has special properties when different forms diseases. Based on the form of the fever, one can assume the type of plasmodium that caused it.

The prodrome is followed by a period at the height of the disease, which is characterized by the appearance of the main clinical symptoms of the disease. It can develop either rapidly (then they speak of an acute onset) or slowly, sluggishly. Its duration varies depending on the state of the body and the capabilities of the pathogen.

Rice. 6. Typhoid Mary, who worked as a cook, was a healthy carrier of typhoid fever bacilli. She infected typhoid fever more than half a thousand people.

Many infections are characterized by an increase in temperature during this period, associated with the penetration into the blood of so-called pyrogenic substances - substances of microbial or tissue origin that cause fever. Sometimes a rise in temperature is associated with the circulation of the pathogen itself in the bloodstream - this condition is called bacteremia. If at the same time the microbes also multiply, they speak of septicemia or sepsis.

Rice. 7. Yellow fever virus.

The end of the infectious process is called the outcome. The following outcome options exist:

• Recovery;
• Lethal outcome (death);
• Transition to chronic form;
• Relapse (reoccurrence due to incomplete cleansing of the pathogen from the body);
• Transition to healthy microbial carriage (a person, without knowing it, carries pathogenic microbes and in many cases can infect others).

Rice. 8. Pneumocystis are fungi that are the leading cause of pneumonia in people with immunodeficiencies.

Classification of infections

Rice. 9. Oral candidiasis is the most common endogenous infection.

By the nature of the pathogen, bacterial, fungal, viral and protozoal (caused by protozoa) infections are distinguished. Based on the number of pathogen types, they are distinguished:

• Monoinfections – caused by one type of pathogen;
• Mixed or mixed infections - caused by several types of pathogens;
• Secondary - arising against the background of already existing disease. Special case– opportunistic infections caused by opportunistic microorganisms against the background of diseases accompanied by immunodeficiencies.

By origin they distinguish:

• Exogenous infections, in which the pathogen enters from the outside;
• Endogenous infections caused by microbes that were in the body before the onset of the disease;
• Autoinfections are infections in which self-infection occurs by transferring pathogens from one place to another (for example, candidiasis oral cavity, caused by the introduction of fungus from the vagina with dirty hands).

According to the source of infection there are:

• Anthroponoses (source – humans);
• Zoonoses (source: animals);
• Anthropozoonoses (the source can be both humans and animals);
• Sapronoses (source - environmental objects).

Based on the location of the pathogen in the body, local (local) and general (generalized) infections are distinguished. According to the duration of the infectious process, acute and chronic infections are distinguished.

Rice. 10. Mycobacterium leprosy. Leprosy is a typical anthroponosis.

Pathogenesis of infections: general scheme of development of the infectious process

Pathogenesis is the mechanism for the development of pathology. The pathogenesis of infections begins with the penetration of the pathogen through the entrance gate - mucous membranes, damaged integument, through the placenta. The microbe then spreads throughout the body in various ways: through the blood - hematogenously, through the lymph - lymphogenously, along the nerves - perineurally, along the length - destroying the underlying tissues, through physiological pathways - along the course, for example, of the digestive or reproductive tract. The final location of the pathogen depends on its type and affinity for a certain type fabrics.

Having reached the site of final localization, the pathogen exerts a pathogenic effect, damaging various structures mechanically, with waste products or by releasing toxins. Isolation of the pathogen from the body can occur with natural secretions - feces, urine, sputum, purulent discharge, sometimes with saliva, sweat, milk, tears.

Epidemic process

An epidemic process is the process of spreading infections among the population. The links in the epidemic chain include:

• Source or reservoir of infection;
• Path of transmission;
• Receptive population.

Rice. 11. Ebola virus.

A reservoir differs from a source of infection in that the pathogen accumulates in it between epidemics, and under certain conditions it becomes a source of infection.

Main routes of transmission of infections:

1. Fecal-oral – with food contaminated with infectious secretions, hands;
2. Airborne - through the air;
3. Transmissible - through a carrier;
4. Contact – sexual, through touching, through contact with infected blood, etc.;
5. Transplacental - from a pregnant mother to a child through the placenta.

Rice. 12. H1N1 influenza virus.

Transmission factors are objects that contribute to the spread of infection, for example, water, food, household items.

Based on the coverage of a certain territory by the infectious process, the following are distinguished:

• Endemics are infections “tied” to a limited territory;
• Epidemics are infectious diseases covering large territories (city, region, country);
• Pandemics are epidemics that span several countries and even continents.

Infectious diseases make up the lion's share of all diseases faced by humanity. They are special in that during them a person suffers from the vital activity of living organisms, albeit thousands of times smaller than himself. Previously, they often ended fatally. Despite the fact that today the development of medicine has made it possible to significantly reduce the mortality rate of infectious processes, it is necessary to be alert and aware of the peculiarities of their occurrence and development.

Definition of the concepts “infection”, “invasion”, “infectious process”, “infectious disease”.

Infection is the infection of living organisms by bacteria or viruses, or fungi, or protozoa. In medicine, the term infection means different kinds interaction of foreign microorganisms with the human and animal body.

Types of infections

The infection can develop in different directions and take different forms. The form of infection development depends on the ratio of the pathogenicity of the microorganism, the factors protecting the macroorganism from infection and environmental factors.

Local infection is local damage to body tissues under the influence of pathogenic factors of a microorganism. A local process, as a rule, occurs at the site of penetration of the microbe into the tissue and is usually characterized by the development of a local inflammatory reaction. Local infections are represented by sore throats, boils, diphtheria, erysipelas, etc. In some cases, a local infection can develop into a general one.

General infection is the penetration of microorganisms into the blood and their spread throughout the body. Having penetrated the tissues of the body, the microbe multiplies at the site of penetration and then penetrates the blood. This development mechanism is typical for influenza, salmonellosis, typhus, syphilis, some forms of tuberculosis, viral hepatitis, etc.

Latent infection is a condition in which a microorganism living and multiplying in the tissues of the body does not cause any symptoms (chronic form of gonorrhea, chronic salmonellosis, etc.)

Invasion (from Latin invade - invasion, attack) is a multi-valued biological term.

2) diseases caused by pathogens - animals (for example, helminthic infestations - helminthiasis) or protists (protozoal infestations - malaria, leishmaniasis, etc.). Diseases caused by protists are often classified as infections.

In oncology, invasion is the ability of cancer cells to separate from it and penetrate into surrounding tissues. Thus, the ability to invade is a necessary condition for tumor metastasis.

In zoology, botany, ecology and biogeography, invasion is often called the introduction of new species into territories where they were previously absent, which occurs (unlike introduction) without conscious human participation.

In psychology, invasion is a condition in which the unconscious dominates in the psyche of a healthy person (according to C. G. Jung).

Infectious process – a complex multicomponent process of dynamic interaction of infectious pathogenic agents with the macroorganism, characterized by the development of a complex of typical pathological reactions, systemic functional changes, hormonal status disorders, specific immunological defense mechanisms and nonspecific resistance factors.

The infectious process forms the basis for the development of infectious diseases. The practical significance of knowledge of the etiology and pathogenesis of infectious diseases, the general patterns of their development is due to the fact that infectious diseases for a long time occupy third place in prevalence after diseases of the cardiovascular system and oncological pathology

Infectious diseases is a group of diseases caused by the penetration of pathogenic (disease-causing) microorganisms into the body. In order for a pathogenic microbe to cause an infectious disease, it must have virulence, that is, the ability to overcome the body's resistance and exhibit a toxic effect. Some pathogenic agents cause poisoning of the body with exotoxins released by them in the process of life (tetanus, diphtheria), others release toxins (endotoxins) during the destruction of their bodies (cholera, typhoid fever).

One of the features of infectious diseases is the presence of an incubation period, that is, the period from the time of infection until the appearance of the first signs. The duration of this period depends on the method of infection and the type of pathogen and can last from several hours to several years (the latter is rare). The place where microorganisms enter the body is called the entry gate of infection. Each type of disease has its own entrance gate, for example, Vibrio cholerae enters the body through the mouth and is not able to penetrate the skin. Contents

1 Classification

2 Prevention

3 Literature

Classification

There are a large number of classifications of infectious diseases. The most widely used classification of infectious diseases by L. V. Gromashevsky:

intestinal (cholera, dysentery, salmonellosis, escherichiosis);

respiratory tract (influenza, adenovirus infection, whooping cough, measles, chicken pox);

“blood” (malaria, HIV infection);

external integument (anthrax);

with different transmission mechanisms (enterovirus infection).

Depending on the nature of the pathogens, infectious diseases are classified into:

prion (Creutzfeldt-Jakob disease, kuru, fatal familial insomnia);

viral (influenza, parainfluenza, measles, viral hepatitis, HIV infection, cytomegalovirus infection, meningitis);

bacterial (plague, cholera, dysentery, salmonellosis, streptococcal, staphylococcal infections, meningitis);

protozoans (malaria, amoebiasis, balantidiasis, toxoplasmosis);

fungal infections, or mycoses (athlete's foot, candidiasis, cryptococcosis, aspergillosis, mucormycosis, chromomycosis).

Preventive measures:

carrying out preventive vaccinations

quarantine measures

curing the source of infection.

Quarantine is a set of measures to stop the spread of infection, this includes isolating previously ill people, disinfecting the place of residence, identifying those in contact with sick people, etc.