Lecture 15&16 - The intestinal microbiome Flashcards
What is the intestinal microbiome?
A highly complex network fo bacteria, viruses, fungi, phages, yeast and archaea.
What is the purpose and function of the intestinal microbiome?
- Host defence/pathogen invasion: suppress the expansion of pathogenic organisms.
- Nutrients/digestion/vitamins/ metabolic processes
- Immune system development: host’s immune system continuously surveying the ‘microbial landscape’ and the bacteria are integral to the development of this relationship.
- Intestinal epithelial maintenance cell renewal
What are enterocytes?
Simple columnar cells which line the inner surface of the small and large intestines. The specific groups of bacterial communities in a population are known as enterocytes.
What are the three enterotypes of bacterial patterns?
- Enterotype 1 = bacteriodes
- Enterotype 2 = Prevotella
- Enterotype 3 = Ruminococcus
What can alter enterotype?
Age, geography, birth mode, antibiotics, genetics, diet.
How does diet change enterotype?
Post-infancy the diet is key to shaping the composition of the microbiome. Diet can also cause changes even over short periods of time.
High fibre diets = fibre-fermenting bacteria thrive and grow
High protein/meat based diet = Growth of different strains of bacteria.
How do antibiotics change the enterotypes?
Their use in controlling growth of unwanted pathogenic bacteria can also have non-selective effects and destroy communities of beneficial microbes. The destruction and compositional changes evoked by antibiotic use can allow the onset of dysbiosis. however the effect on the intestinal microbiome is dependent on the spectrum of antibiotic taken.
What medications (other than antibiotics) can effects the microbiome?
Metformin is the drug commonly used in type 2 diabetes and has recently shown to alter the intestinal microbiome. Studies show this is the cause of the drug’s common side effects in the digestive system. Iron supplement for treatment of IDA can alter the microbiome and increased likelihood of pathogenic growth.
How can genetics/sex change the intestinal microbiome?
Twins have more similarities in the intestinal microbiome than unrelated individuals. it is also found that sex difference in gut microbiota do not appear until puberty. So the role of sex hormones in shaping gut microbiota composition is likely.
What is dysbiosis?
An imbalance between the types of organism present in an individuals natural microflora
What is gastroenteritis?
A form of acute intestinal inflammation and results in diarrhoea
What causes inflammatory bowel disease (IBD)?
Genetic predisposition, immune system disturbance, environmental triggers
How can we re-establish the healthy microbiome and overcome the dysbiotic state?
- Prebiotics
- Probiotics
- Faecal microbial transplantations
How can probiotics be used to re-establish the heathy microbiome?
- Microbiome has the ability to ferment fibrous substrates, this can promote the growth of specific bacteria strains that metabolise such nutrients, this can be adopted to support the growth of selective bacteria within the colon
- This does not contain microorganisms, only selective fermentation components.
How can probiotics be used to re-establish the healthy microbiome?
- formulations that contain microorganisms and when taken in appropriate doses so they can reach the colon intact and viable, are able to engraft, colonise and promote intestinal health.
- They can compete with pathogenic bacteria for colonisation niches.
