The human microbiota/ normal flora comprises the populations of microbial species that live on or in the human body. The biggest populations of microbe reside in the gastrointestinal tract. Evidences showed that the gut is the epicentre of antibiotic resistance. How these microbial population (that are estimated to be over 1,000 different species) contribute for antimicrobial resistance?
Dear Awoke...
Its all about the genetic background of such flora...
Have a look to the link below.
Article Resistance to antibiotics in the normal flora of animals
Intestines are a habitat of bacteria. In this niche they occur in high density, which makes interspecies interactions (i.e. horizontal gene transfer) highly intensified. It is proposed that also probiotic bacteria (having resistance genes) may be a potential source of resistance to pathogenic bacteria.
https://www.hindawi.com/journals/ijmicro/2011/312956/
Article Horizontal gene transfer in the human gastrointestinal tract...
Also when we take antibiotics for other infections we often eat them and these antibiotics are not fully absorbed in the gut- gut bacteria are constantly exposed to different levels of antibiotic concentrations and therefore they can develop reistance which then again spread to other members of the gut population like described above.
Conjugation is a key driver of antibiotic resistance and hapens frequenctly amomg proteobacteria - there is a lot of proteobacteria in the gut.
some litterature: Article Antibiotics and the Human Gut Microbiome: Dysbioses and Accu...
Well
Antibiotic resistance is mainly genetic encoded(genes located in plasmids) and due to other reasons such as enzyme secretion,thickning of cell wall and enzyme production.It was found recently that antibiotic resistance genes can be transformed within gut bacteria.For instance van a gene of VRSA was found in Enterococci that are occuring as gut microflora,lactobacilli.
Hi Awoke,
Regular use of antibiotics, which cause the changes in genes. Mutation can also be the reason. And this can be spread to whole intestinal microbiota through horizontal gene transfer.
We can say manythings about antibiotic resistance in gut microflora.It is a desired phenomenon for probiotic bacteria attaching epithelial tissues with certain benefits such as production of enzymes,antimicrobial proteins and acids.Random transformation of antibiotic resistance genes to probiotics is of interest and needs more studies in details.
Antimicrobial resistance is multi-factorial. Sub-optimal exposure to antimicrobial, gene transfer (both horizontal and vertical), spontaneous mutation are among the many. When there is frequent infection, there will be exposure to broad spectrum antimicrobials which will result in selection pressure in which resistant strains are selected. These strains will constantly evolve and result in gene transfer, both horizontal and vertical. The spontaneous mutation also contribute to the emergence of resistance.
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