Lecture 15 - Microbiome 2 Flashcards
Compare the microbiota between individuals
Different individuals will have the same phyla present, but different species
To which infections does dysbiosis lead?
Salmonella
Overgrowth of:
- Candida
- Clostridium difficile
Which bacterium is responsible for Pseudomembranous colitis?
Clostridium difficile
Are many people infected with Clostridium difficile?
3%
Describe how Clostridium difficile can overgrow
- Gut microbiota altered (antibiotics)
- Reduced competition, C. difficile overgrow
- Cytotoxin toxin produced
- Cell death, inflammation and bowel necrosis
Which people are most likely to get Pseudomembranous colitis?
Where do outbreaks normally occur?
People taking antibiotics
Outbreaks are common in hospitals, where people are taking antibiotics
Describe the gut microbiota of individuals who get recurrent C. difficile infections
Reduced diversity of gut microbiota
(compared to people who get single infections / no infections
How can normal gut microbiota be reinstated in people with recurrent C. difficile infections?
Faecal transplant
What must we do before we give someone a faecal transplant?
Why?
Rationally select the bacteria in the transplant, so we know what we are giving the other people
This is so the recipient doesn’t receive unknown pathogens that could cause disease
How may else may gut microbiota cause disease?
Moving to extra-intestinal sites:
- wounds
- respiratory tract
- urinary tract
- blood
In what circumstances will gut microflora cause infection of other sites?
Abnormal host:
- anatomical
- functional
- immunocompromised
Which gut microflora causes UTIs?
E. coli
Which microflora causes wound infection?
Klebsiella
Bacteroides sp.
Which microflora bacterium causes Lower Respiratory tract infection?
Klebsiella
Intestinal microbiota are a rich source of …
DNA
Why is the gut microbiota important for immunity?
Microbial colonisation is linked with development of the immune response, through the differentiation of Treg
Describe the importance of gut microflora on asthma and allergies
Reduced incidence when mother is exposed to animals
Children who develop atopy have a higher incidence of …
Clostridia compared to non-atopic children
What is the connection between caesarian sections and disease?
Children who were delivered by C section are 20% more likely to have asthma
Which diseases are associated with abnormal gut microbiota?
- Asthma
- Allergies
- Eczema
- Inflammatory bowel disease
- C. difficile - Pseudomembranous colitis
What is inflammatory bowel disease associated with?
- Inappropriate immune response against intestinal microflora
- Reduced diversity
What happens to intestinal permeability in patients with IBD?
Increased intestinal permeability
What are prebiotics?
These are dietary supplements that promote beneficial bacteria
What are probiotics?
Doses of beneficial bacteria in the diet
Which bacteria are commonly administered as probiotics?
Lactobacillus sp.
What do probiotics supposedly protect against?
- Rotavirus
- Childhood diarrhoea
- Atopic eczema
What are the three general things that affect the immune system?
- Nutrients
- Infection with enteropathogens
- Gut microbiota
Describe how the diet affects microbiota in the gut
Varying the levels of protein, monosaccharides, polysaccharides and lipids changes the numbers and types of bacteria in the gut
How does microbiota affect the metabolism?
How?
Without microbiota, a higher energy intake is required.
- Directly provide nutrients (Vik K, biotin, folate CHO from cellulose)
- Alter metabolic machinery of host cells
Describe how differences in microbiota in a population affects metabolism of the population
Despite differences in microbiota, the individuals had stable metabolic pathways
Obesity / high fat diet is associated with an increase in which phyla?
What about decrease?
In general?
In general:
decreased diversity of microbiota
Increase:
- Firmicutes
- Actinomycetes
Decrease:
- Bacteroides
What is the role of actinomycetes in obesity?
This phlum enriches metabolic pathways associated with obesity
–> increased capacity for energy harvest
What happens to the inflammatory response in high fat diets?
Increased inflammatory responses
What is the effect of ‘obesity’ microbiota on the brain?
Decreased satiety
What is the effect of ‘obesity’ microbiota on the liver?
Increased SCFAs
Increased inflammation
What is the effect of ‘obesity’ microbiota on the adipose tissue?
Increased Triglyceride incorporation
What is the effect of ‘obesity’ microbiota on muscle?
Decreased fatty acid oxidation
What is the effect of ‘obesity’ microbiota on the GIT epithelium?
Increased permeability
In general, what is the role of gut microbiota in malnutrition?
Malnutrition at a young age seems to permanently affect the make up of the microbiota in the gut
What was the conclusion from the Kwashiokor study?
The gut microbiota was responsible for propagating the severe and acute undernutrition
Describe the results of the study?
- Malawian twins; one fed well, one poorly
- Intervention: both given theraputic food
- Both twins had an increase in variability whilst on the food
- After food was removed, only the previously healthy twin maintained the variability of the microbiota
What did a switching of diet bring about in mice?
Rapid change in the diversity of the microbiota
What happens to the metabolism of mice with Kwashiorkor microbiota?
How?
Reduced TCA cycle
A product from the microbiota inhibits enzymes in this cycle
What is inflammatory bowel disease?
A general name for diseases such as:
• Crohn’s disease
• Ulcerative colitis
