Definitions Flashcards
What are probiotics?
Added live bacteria that don’t stay in the gut
Do probiotics stay in the gut?
No they don’t become resident in gut
What are the benefits of probiotics?
- Produce vitamins
- Direct antagonism (pathogens)
- Competitive exclusion
- Barrier function
- Reduce inflammation
- Stimulate Immune System
What are prebiotics?
Dietary food for resident gut bacteria
What is the purpose of prebiotics?
Provide food/ nutrition- boost numbers of beneficial bacteria
Where can prebiotics be found?
They occur naturally in some plants and are added to certain cereals, biscuits etc
What are the benefits of prebiotics?
- Improve gut function- bulk stool= better transport
2. Manage IBS via reducing inflammatory markers
What are FOS/ inuline prebiotics function?
Increase Ca absorption= Inc bone heath
What are GOS/ FOB prebiotics function?
Find in infant formula, inc bifido bacteria
What are synbiotics?
Combination of pro + pre bionics, not widely used
How does antibiotic treatment work?
Antibiotics create a selection pressure against bacteria
What are the disadvantages of antibiotic treatment?
- Bacterial resistance
2. Kills off commensal bacteria- regrowth will be different from original
What bacteria is commonly overgrown after antibiotic treatment? How do you treat this?
C.Diff tends to overgrow as spores are antibiotic resistant= recurring infection
Treat via a faecal transplant
What is a Faecal Microbial Transplant?
Used to combat C.Diff infection
Sample from a healthy donor- microbe repopulates large intestine (competitive exclusion of C.Diff)
NOTE- Donor has to be screen for virus’, pathogens, fungi etc
What are anaerboic bacteria?
Doesn’t require 02 for growth
What are aerobic bacteria?
Requires 02 for growth
What are facultative bacteria?
Can grow with/ without oxygen
What are obligate bacteria?
Presence of 02 will kill them
What happens to bacterial populations as you move down the GI tract?
Progressively-
Anerobic
Denser
Obligate
What selection pressures of the GI tract change the presence of bacteria as you move further down?
pH
Change in transit time in an area
What are the roles of Microbiotia?
- Metabolism of Dietary Components
2. Defence against pathogens
How does the Microbiota metabolise dietary components?
Microbiota grows on fibre and converts it into smaller products- releases energy into LI
What are the advantages of microbiota metabolism of dietary components?
- Improve faecal bulking- shorter transit time
- Release photochemical- Give Antioxidants
- Maintain acidic pH
- Digest non-digestible components down to short chain FAs
NOTE- different bacteria produce different types of metabolites needed for all types of function
How is lipogenesis involved in energy production for microbiota?
Lipogenesis is an energy source for other bacteria via acetate.
How does the Microbiota defend the body against pathogens?
- Colonisation Resistance- via the Barrier Effect (large numbers prevents colonisation of ingested pathogens + inhibits growth- Active Competitive Exclusion
- pH Inhibition- Pathogens grow best at a pH greater than 6 (more disease in distal colon due to higher pH and slower transit time)
- Mucus Layer- forms a barrier between bacteria and epithelium, bacteria are a secondary barrier to stop adhesion of pathogens (if pathogens broke through would elicit an immune response + inflammation)
- Immune System- Gut mucosal immue system is largest lymphoid organ in the body, disruption/ dysbiosis- inflammation
What pH do pathogens grow best in and in what area of the GI tract are the most likely to cause disease because of this?
Pathogens grow best at a pH greater than 6 and most commonly cause disease in the distal colon due to a slower transit time and low fermentation rate
What is an autoimmune reaction?
When immune system can’t distinguish between pathogens and commensal
What can cause changes to microbiota?
Diet
Life Stage
Environment
What factors affect the ability of a drug?
Absorption- pH, gut length, transit time
Distribution- albumin levels (low=less binding so inc free drug conc.)
Metabolism- gut bacteria, gut wall metabolism
Excretion- Biliary, Kidney rates
