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"Child`s Health" 6 (57) 2014

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Infection and infecting - the key moments occurrence of infectious disease

Authors: I.V. Bogadelnikov, E.A.Kryuger, A.V. Bobrysheva, N.I. Muzhetskaya - Crimea State Medical University named after S.I. Georgievsky, Department of Pediatrics with the Course of Child''s Infectious Diseases, Simferopol

Categories: Pediatrics/Neonatology

Sections: Specialist manual

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It is known that microorganisms found in soil, water, air, plants, in humans and animals. They can be found in all environments and are essential components of any ecological system and the biosphere as a whole. In indoor air 1 m3 contains 15-20 thousand cells, and on the human body is 20 to 1000 million microorganisms (of one handshake clean hands transmitted 32 million microbes!, and kiss (lips and tongue contact) leads to contact with 42 million germs). Thus, infection, i.e. enter different micro-organisms in or on the human body is a normal state a necessary condition for human life support. According to WHO recommendations, immediately after birth, it is necessary to provide the most intimate contact with its mother is directly in the delivery room (attachment to the breast, the location newborn on the body of the mother or even father! - method "kangaroo"). When this happens the skin and gastrointestinal tract colonization of maternal microorganisms that healthy immunocompetent child leads to the formation of a protective biofilm. It was found that not only the higher animals and man, but "primitive" organisms, including unicellular organisms are capable of one or another form of collective interactions, exchange of information, formation of a more or less coherent associations of many individuals. But these properties of microorganisms appear only in the presence of colonies formed, and then the pathogen enters the body, is a community of microorganisms that can act as a possible cause or component in the development of infectious disease. That is, as the survival of microorganisms in nature or survival of pathogens in humans is associated with their ability to form colonies irrespective of localization. But since the establishment of the colony, the infection process is transformed into a process of human infection with pathogenic (stranger) microorganism.  But only on condition of formation of colonies is possible to implement an aggressive pathogenic potential (someone else's) microorganism. Microorganisms that live in biofilms, are specialized by function, morphologically differentiated, which leads to aggression.  Is implemented this mechanism, thanks to their special signaling molecules that are responsible for the mobilization and accumulation of bacteria in one place, biofilm formation and the formation of the lesion. Signaling molecules capable of moving not only from one bacterial cell to another, but also penetrate into human cells, affecting their work that facilitates the creation of the colony. These properties are found out in Pseudomonas aeruginosa, for example, N-acylmoleculeshomoserinelactone (AHL). Not only bacteria but also viruses have the such qualities. It has been found that viruses, particularly retroviruses HTLV-1, are able to form complexes similar to the bacterial biofilm. Thanks biofilm viruses protected against the immune system, allowing them to quickly spread from cell to cell. It is normal microflora, individual, genetically determined for each individual creates one of the most important protective barriers person aimed at preventing its settlement by outsiders, including pathogenic macro-organisms. The conversion of the infection process in process of infecting depends on the pathogen (its ability to form a colony of their own kind), and from the microorganism, and colonization resistance of the normal microflora.  Colonization resistance of normal human microflora provided specific mechanisms of protection against many microbial pathogens: the ability to bind to the receptors, thus limiting the colonization of pathogens places of their location; synthesis of microbicides that inhibit the growth of any trapped outside (pathogenic and non-pathogenic) flora; decrease intraluminal pH that leads to the creation of the optimal conditions for the growth of the microflora of their own from one side and the suppression of the pathogenic flora from the other; competition with transient microflora for nutrients and growth factors needed to build colonies. Therefore, any outsider, not "own" micro-organism that falls in the biofilm, is regarded as "foreign" and, most of all, safely killed and the mechanism of neutralization of foreign (alien) microorganisms in immunocompetent people well debugged.  And as long as human biofilm is not damaged in any factor (physical, chemical, biological, radiation, etc.), no disease does not occur because the microorganism is caught outside, primarily genetically alien and can not qualify for life, that is the ability to create their own colony, and if there is no colony, no damaging potential. Because themselves separate microorganisms even in large numbers, are not harmful to the body. At the same stage of infection, in parallel with a biological defense mechanism, there is another protection barrier representing human innate immunity. But pathogenic microorganisms there are mechanisms to protect them from the factors of nonspecific protection. So, Pseudomonas aeruginosa, finding approximation leukocyte sends warning signal to neighbors and together they begin to produce more ramnolipids, which are attached to the surface of the biofilm and destroy leukocytes. As a result, the colony is protected. This same phenomenon underlies the formation of bacterial resistance to antibiotics. Bacteria trapped in the body, such as staphylococci (Staphylococcus aureus), attack the body not immediately because the production of the toxin only a few cells causes a strong immune response. Therefore, by signaling molecules selection toxins delayed until as long as bacterial population to grow significantly, and only then comes the actual aggression. In such a situation, the human immune system is not always able to suppress bacterial aggression, thereby developing dangerous infectious diseases of the skin, soft tissues, bones and joints. In a number of reasons (physical, chemical, pharmacological, and other factors on the biofilm of the human body), especially if it is combined with insufficiency (weakness) of innate immunity, is the destruction of the biofilm and the loss of its its protective properties to microorganisms coming from outside. Only under these conditions have penetrated from the outside agent (microorganism), creates opportunities for colonization of this area of the human body and there are prerequisites for a possible pathogen contact (and the products of its life) to the cells and tissues of the body, ie infection occurs and the emergence of the state, called disease.

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