The Gut Microbiota in Health and Disease

Question 1

How does the gut microbiota prevent against disease?

Answer 1

Microbiota determines the metabolite concentrations that are absorbed from the gut, correct metabolites create a stronger immune system

Question 2

How do bacteria that usually live asymptomatically in their host end up causing diseases if unregulated?

Answer 2

• Become too highly concentrated, too many of their products produced
• Colonisation of a different body site (sepsis)

Question 3

How is the gut microbiota often implicated in IBD?

Answer 3

Cause of the inflammation in IBD is often an inappropriate host reaction towards gut microbiota

Question 4

Why can it be difficult to assess the effect of IBD on gut microbiota and vice versa?

Answer 4

Because many of the treatments for IBD (such as antibiotics / immunosuppressants) can alter the gut microbiota themselves

Question 5

What features of IBD can alter the gut microbiota?

Answer 5

• Inflammation
• Diarrhoea (reduced transit time alters bac)
• Host diet
• Host genotype

Question 6

How does inflammation cause altered gut microbiota?

Answer 6

• Causes reduction in the mucous barrier which increases oxygen exposure for gut bacteria
• Causes different bacteria to thrive than would normally be the case

Question 7

What is a probiotic?

Answer 7

A live microorganism that confers a health benefit to the host when acquired in appropriate amounts

Question 8

What is a prebiotic?

Answer 8

A substrate that is selectively used by host microorganisms, coferring a health benefit

Question 9

Probiotic vs prebiotic?

Answer 9

• Probiotic: added live bacteria

- Prebiotic: food for resident bacteria

Question 10

What are the functions of probiotics?

Answer 10

• Competition (with other possibly bad organisms)
• Bioconversions (making products)
• Direct antagonism (towards pathogens)
• Barrier function
• Reduce inflammation
• Immune stimulation

Question 11

What mineral does consumption of prebiotics improve absorption of?

Answer 11

Calcium

Question 12

How does antibiotic treatment affect the gut microbiota?

Answer 12

• Selective pressure reduces diversity, some thrive others die off completely
• Just after antibiotic therapy much more likely to get gut infection due to reduced organism diversity

Question 13

For recurring gut infections that are not adequately managed by antibiotics, what treatment is often effective? Which organism commonly commits recurring infections?

Answer 13

• FMT: Faecal Microbial Transplantation
• Screen faecal sample from donor, then input it into the host. Donor microbiota repopulates large intestine
• C. Difficile