What is an infection: definition, features and types

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

Basic concepts

An infection is a complex of relationships between different 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, bacterium) into a living macroorganism, in response to which a specific protective reaction arises on the part of the host.

Features of the infectious process:

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

Periods

The concept of infection is also based on the cyclicity of the pathological process. The existence of periods in development is typical for 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 period of prodromation is the appearance of a general clinic, characteristic of the majority of 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, tissue damage at the local level.
4. Reconvalescence - the time of extinction of the clinical picture and recovery of the patient.

Types of infectious processes

In order to consider in more detail the question of what an infection is, you need to understand what it is. There is a significant number of classifications depending on the origin, current, localization, the number of microbial strains, and so on.

1. By the method of penetration of pathogens:

• Exogenous process - characterized by the penetration of a pathogenic microorganism from the external environment;
• Endogenous process - there is an activation of its own conditionally pathogenic microflora under the influence of unfavorable factors.

2. By origin:

• Spontaneous process - characterized by a lack of human intervention;
• Experimental - the infection was artificially induced in the laboratory.

3. By the number of microorganisms:

• Monoinfection - caused by one type of pathogen;
• Mixed - several types of pathogens are involved.

4. By order:

• The primary process is a newly emerging disease;
• Secondary process - accompanied by the addition of additional infectious pathology in the background of the primary disease.

5. Localization:

• The local form - the microorganism is located only in the place through which it penetrated the host's body;
• Generalized form - pathogens spread throughout the body with further settling in certain favorite places.

If microbes spread with blood flow, but do not multiply there, this condition is called viremia (causative agent - virus), bacteremia (bacterium), fungi (fungi), parasitemia (protozoa). In the case of proliferation of pathogenic microorganisms, sepsis develops in the blood.

6. Down stream:

• Acute infection - has a vivid 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 at the age of 2 to 10 years (chicken pox, diphtheria, scarlet fever, whooping cough);
• The concept of "adult infection" as such is not present, because to those pathogens that cause the development of the disease in adults, the children's organism is just as sensitive.

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

Ways of hitting

Distinguish the following ways of penetration of microorganisms, which ensure the transfer of pathogens from the environment into the host organism:

• Fecal-oral (consists of alimentary, aqueous and contact-household);
• Transmissible (blood) - includes sexual, parenteral and through insect bites;
• Aerogenic (air-dust and airborne);
• Contact-sexual, contact-wound.

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

Localization of the infectious process

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

1. Intestinal. Pathological process occurs in the departments of the gastrointestinal tract, the causative agent penetrates the fecal-oral route. This includes salmonellosis, dysentery, rotavirus, typhoid fever.
2. Respiratory. The process occurs in the upper and lower respiratory tract, microorganisms "move" in most cases through the air (influenza, adenovirus infection, parainfluenza).
3. Outdoor. Pathogens contaminate mucous membranes and skin, causing fungal infections, scabies, microsporia, STDs.
4. Blood. The infection gets through the blood, spreading further throughout the body (HIV infection, hepatitis, diseases associated with insect bites).

Intestinal infections

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

Diseases of the presented group can be caused by pathogens of bacterial, fungal and viral origin. Viral microorganisms that can penetrate various parts of the intestinal tract are rotaviruses and enteroviruses. They are able to spread not only by the fecal-oral route, but also by the air-droplet, 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 of antibacterial or hormonal drugs, with immunodeficiency.

Rotaviruses

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

Rotavirus enteric infection in children is much more severe than in adults. The stage of acute manifestations is accompanied by the following clinical picture:

• abdominal pain;
• Diarrhea (stool has a light color, there may be impurities of blood);
• Fits of vomiting;
• Hyperthermia;
• Coryza;
• Inflammatory processes in the throat.

Rotavirus enteric infection in children in most cases is accompanied by outbreaks in school and preschool institutions. By the age of 5, most of the kids felt the effect of rotaviruses on themselves. The following infections are not as severe as the first clinical case.

Surgical infection

Most patients who need surgical intervention are interested in the question of what a surgical type infection is. This is the same process of interaction of the human body with a pathogenic agent, only arising on the background of surgery or requiring surgical intervention to restore functions for a particular disease.

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

Depending on the location of the surgical infection, the following diseases are distinguished:

• Soft tissues;
• Joints and bones;
• The brain and its structures;
• Abdominal cavity organs;
• Organs of the chest cavity;
• Pelvic organs;
• Separate elements or organs (mammary gland, hand, foot, etc.).

Pathogens of a surgical infection

At present, the most frequent "guests" of acute purulent processes are:

• Staphylococci;
• Pseudomonas aeruginosa;
• Enterococcus;
• E. coli;
• streptococcus;
• Proteus.

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

Treatment of infection

At the heart of 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 medicines are used:

1. Antibiotics (if the pathogen is a bacterium). The choice of a group of antibacterial agents and a specific preparation is made on the basis of bacteriological research and determination of the individual sensitivity of the microorganism.
2. Antiviral (if the pathogen is a virus). In parallel, drugs that strengthen the defenses of the human body are used.
3. Antimycotic agents (if the pathogen is a fungus).
4. Anthelmintic (if the pathogen is helminth or the simplest).

Treatment of infections in children under 2 years old is performed in a hospital in order to avoid the development of possible complications.

Conclusion

After the occurrence of the disease, which has a specific pathogen, the specialist conducts differentiation and determines the need for hospitalization of the patient. It is necessary to specify the specific name of the disease in the diagnosis, and not simply the word "infection". The case history, which is given 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.