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GI > Gut microbiota in health and disease > Flashcards

Gut microbiota in health and disease Flashcards

1
Q

list some factors that might affect the gut microbiota

A 
environment 
probiotics
antibiotics
prebiotics
faecal transplant
disease
diet
lifestage
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2
Q

what must you alway question if there is dysbiosis

A

whether it is the cause or consequence of a disease

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3
Q

give examples of diseases that can occur from microbes that normally live asymptomatically in the host

A 
MRSA - staph aureus
strep throat
gingivitis
acne
meningitis
pneumonia
diarrhoea - c. diff
thrush
UTI
gastric cancer - helicobactor pylori
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4
Q

give example of disease that occurs when a bacterium colonises in a different site from where it is meant to be

A

sepsis

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5
Q

where does the inflammation in IBD most likely come from

A

dysregulated host immune response to gut microbiota

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6
Q

give some examples of evidence of the role of microbes in IBD development

A
  1. Increased mucosal bacterial load is observed in IBD patients
  2. Broad spectrum antibiotics can have some efficacy in reducing symptoms
  3. Faecal stream diversion induces remission in Crohn’s disease
  4. IBD does not occur in germ-free animals
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7
Q

whats is the bacterial diversity like in patients with IBD

A

reduced diversity

often a reduction in firmicutes (gram+ve)

increase in facultative anaerobes (e.g. e.coli)

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8
Q

how does IBD manifest

A

non-uniformly - patients have regions of healthy tissue adjacent to inflamed regions

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9
Q

what features of IBD itself could affect the microbiota

A 
antibiotic use
inflammation
diarrhoea
host diet
host genotype
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10
Q

what is the impact of antibiotics on gut microbiota

A

reduced bacterial diversity and increases in enterobacteriaceae can occur as a result of broad spectrum antibiotic use

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11
Q

what is the impact of inflammation on the gut

A

Reduced bacterial diversity and increases in enterobacteriaceae will occur as a result of inflammation

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12
Q

how does inflammation reduce bacterial diversity

A

vicious cycle:

inflammation

  • decrease in mucus barrier
  • increase in O2 exposure
  • alters microbial composition
  • increases inflammation
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13
Q

how can diarrhoea affect microbial composition

A

decreases transit time

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14
Q

how can the host diet affect microbial composition

A

desire to eat less fibre

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15
Q

define probiotics

A

live microorganisms which, when administered in adequate amounts
confer a health benefit on the host

i.e. ADDED LIVE BACTERIA to eg yogurt, supplements, etc

**beneficial in the treatment and prevention of GI diseases

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16
Q

define prebiotics

A

a substrate that is selectively utilized by host microorganisms
conferring a health benefit

i.e. FOOD for resident bacteria, found naturally in some plant foods, also can be added to biscuits, bread, drinks, yogurts, supplements, etc

17
Q

what are the three main mechanism of action groups for probiotics

A
  1. widespread - genus or species relatively unimportant
  2. rare - ie strain specific effects
  3. frequent - genus or species important, strain relatively unimportant
18
Q

what actions are present in widespread mechanisms

A

competition
competitive exclusion
barrier function
reduced inflammation

19
Q

what actions are present in rare mechanisms

A

production of vitamins

20
Q

what actions are present in frequent mechanisms

A

bioconversions (diet)
direct antagonism (pathogens)
immune stimulation

21
Q

what are selected prebitoics that can affect microbiota

A

Fructo-oligosaccharides (FOS) and inulin

Galacto-oligosaccharides (GOS)

Lactulose

22
Q

give some health benefits of prebiotics

A

Improved gut function - stool bulking and faster gut transit

Management of Inflammatory bowel disease - reduction in inflammatory markers

Reduce the risk of colon cancer - reduced DNA damage and cell proliferation, faster gut transit

Prebiotic (GOS/FOS) supplementation of infant formula - increases bifidobacteria numbers

Prebiotics (FOS/Inulin) increase calcium absorption and bone health - pH effect

Consumption of prebiotics instead of sugars can lower glycaemic index - induce a lower blood glucose rise after meals compared to those containing sugars

23
Q

what are the different types of exposure to antibiotics

A

direct - e.g. taken orally, IV

indirect - e.g. cattle given antibiotics - still present when meat eaten

24
Q

what do broad spectrum antibiotics cause

A

remove of target pathogen BUT also commensal bacteria

can also cause spread go antibiotic resistance

25
Q

what are the consequences of antibiotic treatment

A 
During and immediately post-antibiotic
treatment
- Decreased microbial diversity
- Opportunity for pathogen colonisation
- Results in pathogen dominated
community
26
Q

how can antibiotic use result in recurrent c.diff infections

A

Clostridium difficile expands to occupy
empty niches following antibiotic therapy

Overgrowth of C. difficile results in toxin
production, abdominal pain, fever (CDAD)

Clostridium difficile spores are resistant
to antibiotics

Some C. difficile strains are antibiotic resistant

Results in recurring C. difficile infections

27
Q

what is the initial treatment for c diff associated diarrhoea (CDAD)

A

antibiotic therapy - cures 75%

28
Q

what is the best treatment for recurrent CDAD when antibiotics DONT work

A

FMT (faecal microbial transplantation)

effective in >90% patients with recurring c diff infections

29
Q

how does FMT work

A

Faecal sample from screened healthy volunteer donor transplanted into recipient
(enema, colonoscopy, naso-enteric tube, capsules)

Donor microbiota repopulates large intestine, displaces C. difficile, prevents reinfection

currently only approved for RECURRING CDAD

30
Q

for what diseases is FMT NOT effective in producing disease remission

A

pouchitis (inflammation of the ileal pouch)

ulcerative colitis

31
Q

what is an essential process for the donor in FMT to undergo

A

proper screening for all known pathogens

32
Q

list some of the diseases gut microbes (or the products they create) are linked to

A 
IBS
IBD
CV disease
allergies
obesity
bone health
brain health 
rheumatoid arthritis
diabetes
colorectal cancer
33
Q

what diseases can prebiotics help with

A

colorectal cancer
diabetes
osteoporosis

GI (25 decks)

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