Definitions

Question 1

What are probiotics?

Answer 1

Added live bacteria that don’t stay in the gut

Question 2

Do probiotics stay in the gut?

Answer 2

No they don’t become resident in gut

Question 3

What are the benefits of probiotics?

Answer 3

1. Produce vitamins
2. Direct antagonism (pathogens)
3. Competitive exclusion
4. Barrier function
5. Reduce inflammation
6. Stimulate Immune System

Question 4

What are prebiotics?

Answer 4

Dietary food for resident gut bacteria

Question 5

What is the purpose of prebiotics?

Answer 5

Provide food/ nutrition- boost numbers of beneficial bacteria

Question 6

Where can prebiotics be found?

Answer 6

They occur naturally in some plants and are added to certain cereals, biscuits etc

Question 7

What are the benefits of prebiotics?

Answer 7

1. Improve gut function- bulk stool= better transport

2. Manage IBS via reducing inflammatory markers

Question 8

What are FOS/ inuline prebiotics function?

Answer 8

Increase Ca absorption= Inc bone heath

Question 9

What are GOS/ FOB prebiotics function?

Answer 9

Find in infant formula, inc bifido bacteria

Question 10

What are synbiotics?

Answer 10

Combination of pro + pre bionics, not widely used

Question 11

How does antibiotic treatment work?

Answer 11

Antibiotics create a selection pressure against bacteria

Question 12

What are the disadvantages of antibiotic treatment?

Answer 12

1. Bacterial resistance

2. Kills off commensal bacteria- regrowth will be different from original

Question 13

What bacteria is commonly overgrown after antibiotic treatment? How do you treat this?

Answer 13

C.Diff tends to overgrow as spores are antibiotic resistant= recurring infection
Treat via a faecal transplant

Question 14

What is a Faecal Microbial Transplant?

Answer 14

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

Question 15

What are anaerboic bacteria?

Answer 15

Doesn’t require 02 for growth

Question 16

What are aerobic bacteria?

Answer 16

Requires 02 for growth

Question 17

What are facultative bacteria?

Answer 17

Can grow with/ without oxygen

Question 18

What are obligate bacteria?

Answer 18

Presence of 02 will kill them

Question 19

What happens to bacterial populations as you move down the GI tract?

Answer 19

Progressively-
Anerobic
Denser
Obligate

Question 20

What selection pressures of the GI tract change the presence of bacteria as you move further down?

Answer 20

pH

Change in transit time in an area

Question 21

What are the roles of Microbiotia?

Answer 21

1. Metabolism of Dietary Components

2. Defence against pathogens

Question 22

How does the Microbiota metabolise dietary components?

Answer 22

Microbiota grows on fibre and converts it into smaller products- releases energy into LI

Question 23

What are the advantages of microbiota metabolism of dietary components?

Answer 23

1. Improve faecal bulking- shorter transit time
2. Release photochemical- Give Antioxidants
3. Maintain acidic pH
4. Digest non-digestible components down to short chain FAs
   NOTE- different bacteria produce different types of metabolites needed for all types of function

Question 24

How is lipogenesis involved in energy production for microbiota?

Answer 24

Lipogenesis is an energy source for other bacteria via acetate.

Question 25

How does the Microbiota defend the body against pathogens?

Answer 25

1. Colonisation Resistance- via the Barrier Effect (large numbers prevents colonisation of ingested pathogens + inhibits growth- Active Competitive Exclusion 2. pH Inhibition- Pathogens grow best at a pH greater than 6 (more disease in distal colon due to higher pH and slower transit time) 3. 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) 4. Immune System- Gut mucosal immue system is largest lymphoid organ in the body, disruption/ dysbiosis- inflammation

Question 26

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?

Answer 26

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

Question 27

What is an autoimmune reaction?

Answer 27

When immune system can't distinguish between pathogens and commensal

Question 28

What can cause changes to microbiota?

Answer 28

Diet Life Stage Environment

Question 29

What factors affect the ability of a drug?

Answer 29

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