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Microbiota (human)

Microbial flora harbored by normal, healthy individuals. A number of microorganisms have become adapted to a particular site or ecologic niche in or on their host. Some are normal residents that are regularly found, and if disturbed will rapidly reestablish themselves; others are transient microorganisms that may colonize the host for short periods but are unable to permanently colonize. The normal fetus is sterile, but during and after birth the infant is exposed to an increasing number of microorganisms. Subsequently, those organisms best adapted to survive and colonize particular sites establish themselves and become predominant. Physiologic factors such as the availability of nutrients, temperature, moisture, pH, oxidation-reduction potential, and resistance to local antibacterial substances play an important role in determining the ability of a microorganism to become established at a particular site. The normal indigenous microbial flora is exceedingly complex, consisting of many different species of bacteria, fungi, viruses, and protozoa. The great majority of these commensal and symbiotic organisms are bacteria and fungi.

The indigenous microorganisms play an important role by protecting the normal host from invasion by microorganisms with a greater potential for causing disease. They compete with the pathogens for essential nutrients and for receptors on host cells by producing bacteriocins and other inhibitory substances, making the environment inimical to colonization by pathogens.

In the healthy individual the morphologic integrity of the body surface provides a very effective first line of defense. The intact skin is an efficient physical barrier that can be penetrated by very few microorganisms. The secretion of specific antimicrobial substances and bactericidal fatty acids by the sebaceous glands also retards microbial invasion.

Mucosal surfaces also provide a mechanical barrier in the respiratory, gastrointestinal, and genitourinary tracts. These surfaces are bathed in secretions with antimicrobial activity. In the respiratory tract, mechanical cleansing is accomplished by the cough and mucociliary action. Recurrent infections of the sinuses, middle ear, bronchial tract, and lungs occur in individuals who have an impairment of ciliary activity. These infections are usually caused by Staphylococcus pneumoniae and Haemophilus influenzae, the more virulent pus-forming organisms found in the nasopharynx. Defects in ciliary activity also cause bacterial respiratory infections in cigarette smokers and heavy alcohol drinkers. See Staphylococcus

Once the natural barriers of the skin and mucous membranes are breached, the next major line of defense is the polymorphonuclear leukocytes. Individuals with disorders of these phagocytic cells have an increased incidence of serious infections with their indigenous microflora.

The complement system is another nonspecific mechanism of the body for the elimination of invading microorganisms. Complement proteins in conjunction with organs of the reticuloendothelial system (spleen, liver, and bone marrow) play a key role in the removal of encapsulated bacteria from the bloodstream. Splenectomized individuals and those with a nonfunctioning spleen because of sickle cell disease have an increased incidence of fulminating infections caused by S. pneumoniae, H. influenzae, Neisseria meningitidis, and recently recognized unusual organisms. See Complement



a genus of plants of the family Cupressaceae (cypress). There is one species, Microbiota decussata, which is a monoecious dwarf evergreen shrub. It is 1–1.5 m high and has widely spreading branches. The needles on fertile shoots are scaly or imbricate, while those on young sprouts are acicular. The anther spikelets are oval and yellow. The small, monospermous cones are globose or ovate and consist of two to four scales. The seed itself is oval, smooth, and exalate. The plant grows in areas with severe climates on barren rocky soils, such as those found on the mountain tops and passes of Sikhote-Alin’, at elevations of 900–1,200 m. A rare plant, it is protected by law.


Kurentsova, G. E. Reliktovye rasteniia Primor’ia. Leningrad, 1968.
References in periodicals archive ?
Antibiotic use is known to have a near-immediate impact on our gut microbiota and long-term use may leave us drug-resistant and vulnerable to infection.
0%) of gut microbiota in the study participants [Figure 1]c.
Fortunately, it is possible to improve the amount and types of gut bacteria you ingest to enhance your microbiota.
This study found the fermentable fiber insulin restored gut health and protected mice against metabolic syndrome induced by a high-fat diet by restoring gut microbiota levels, increasing the production of intestinal epithelial cells and restoring expression of the protein interleukin-22 (IL-22), which prevented gut microbiota from invading epithelial cells.
And no question, the microbiota here is different from adults.
The Asia Microbiota Bank (AMB), headquartered in Hong Kong, is pleased to announce they have been joined by a new scientific team member, Subramanya Rao, PhD.
difficile infections with a technology platform for developing rationally selected microbiota products positions Finch Therapeutics Group to deliver on the promise of microbiome therapies to transform public health.
Considering skin from this perspective, he noted, it makes sense that bacterial microbiota for these disparate areas varies widely, with a different mix of bacteria found in the groin than on the forearm.
14] microorganisms, with approximately 1100 prevalent species; notably, the gene content in gut microbiota is at least 150-fold higher than the human genome (7).
This technology has been applied in microbiota studies in humans [7], pigs [8,9], and broiler [10].
00220/full) gut microbiome , we set out to determine whether the microbiota in the gut can be affected not only by our nervous system but also by an unsuspected source 6 our bone marrow.
Se conoce el impacto que las infecciones parasitarias tienen sobre las poblaciones bacterianas (Reynolds et al 2104; Holms et al, 2015), pero no la influencia que las alteraciones en la microbiota puedan tener en el asentamiento y progresion de la infeccion por parasitos.