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Gastroenterology > The Intestinal Microbiota: Prebiotics, Probiotics, Symbiotics > Flashcards

The Intestinal Microbiota: Prebiotics, Probiotics, Symbiotics Flashcards

1
Q

What is the difference between microbiota and microbiome?

A

microbiota: all the living microrganisms that inhabit the host
microbiome: the mutual interaction of these organisms with the host cells

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2
Q

What important role does the microbiota play in host health?

A
  • stimulate the immune system and development of gut structure
  • aid in defense against invading pathogens
  • provide nutritional benefits to the host
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3
Q

what are the different methods of characterizing the microbiota?

A

bacterial culture

molecular technique: RNA/DNA, PCR, analysis of amplicons (denaturing gradient gel electrophoresis (DGGE), temperature gradient gel electrophoresis (TGGE), and terminal restriction fragment length polymorphism (T-RFLP)), quantification (qPCR, FISH)

metagenomics (gene content)

transcriptomics (gene expression)

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4
Q

What are the pros and cons to performing a bacterial culture for microbiota analysis?

A
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5
Q

What type of bacteria predominates in the GI tract?

What specific bacterial groups predominate?

A

anaerobes

Bacteroides, Clostridium, Lactobacillus, Bifidobacterium spp., and Enterobacteriaceae.

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6
Q

What prevents the retrograde movement of bacteria from the colon into the SI normally?

A

ileocolic valve along with normal intestinal motility

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7
Q

The bacterial population in the GI tract is very stable. What are the mechanisms that control the bacterila populations?

A

(1) gastric acid
(2) the antimicrobial effect of bile
(3) intestinal motility
(4) intestinal mucus
(5) local immune responses

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8
Q

What type of archaea are most abundant in the GI tract?

What type of fungi is most abundant?

Most viral sequences represent what type of virus?

A

Methanobacteria or methanogens (metabolize Hydrogen end product of bacterial fermentaiton to methane better than hydrogen sulfite)

yeast and molds

bacteriophage

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9
Q

For PCR amplification of bacteria, what gene is used?

A

16s rRNA

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10
Q

What information does the analysis of amplicons (DGGE, TGGE, T-RFLP) provide?

A

phylogenetic

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11
Q

What is the concepto of colonization resistance?

A

The microbiota also protects the host from invading pathogens→This occurs through competition for oxygen, nutrients, and mucosal adhesion sites as well as creation of a physiologically restrictive barrier for nonresident bacteria.

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12
Q

What allows for communication between the microbiota and host immune system?

What benefits does this communication system provide?

A

TLR (toll-like receptors)

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13
Q

Substances that inhibitbacteiral growth

A

bacteriocins

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14
Q

What is the main product of fermentation that serves as an energy source for the bacteria and promotes epithelial cell growth in the colon?

A

volatile fatty acids (7% of ME)

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15
Q

What are the three main ways GI disease can result in relationship to the microbiota and immune system dysfunction?

A
  1. pathogen colonization
  2. overgrowth of commensal organisms
  3. altered communication
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16
Q

What types of bacteria increase with IBD?

Decrease with IBD?

Increase with boxer histiocytic ulcerative colitis?

A

Proteobacteria in the duodenum

beneficial Clostridium clusters.

adherent and invasive E. coli (respond to treatment with fluoroquinolones)

17
Q

What pathogens that colonize in GI tract often cause GI disease?

A

salmonella

campylobacter

C. difficile

18
Q

What conditions are associated with overgrowth of commensals?

A

dysbiosis

ARD (abx responsive diarrhea)- SI bacterial overgrowth (SIBO)

EPI→SIBO

SX→altered motility

19
Q

Types of altered communication of microbiota and immune system that results in GI disease?

A

shift toward gram negative organisms→decreases colonization resistance

TLR→alterations to T-cells

histiocytic ulcerative colitis in boxers (intracellular E. Coli)

20
Q

What two conditions are abx most commonly used to rebalance the microbiota?

A
  1. intstinal dysbiosis (ARD/SIBO)
  2. IBD
21
Q

What are prebiotics?

What two benefits do they provide?

Examples?

A

nondigestible dietary carbohydrates

Benefits:

  1. stimulate the growth and metabolism of endogenous enteric protective bacteria (Lactobacillus and Bifidobacterium)
  2. increase SCFA

Examples: lactosucrose, fructooligosaccharides (FOS), psyllium, and bran

22
Q

What are probiotics?

A

living microrganisms that impart a health benefit beyond basic nutrition

23
Q

What are the proposed benefits of probiotics?

What are the most commonly studied microrganisms?

A
  • improved epithelial barrier function
  • modulation of mucosal immune system
  • alteration of the microbiota, specifically inhibiting colonization by pathogenic bacteria

Lactobacilli, Bifidobacteria, and Enterococci have been the most commonly studied.

24
Q

What information should the manufacturer provide for a probiotic?

A
  • the number of live, microbial colony-forming units per unit weight
  • genus,
  • species, and (preferably) strain

of each organism

25
Q

What is the optimal level of probiotic currently suggested (in cfu)?

A

1 x 10^8 to 1 x 10^12 cfu/g

26
Q

When would use of probiotics not be appropriate?

A

markedly debilitated, immunocompromised, or have severe clinical signs of intestinal infections such as canine parvovirus (could result in opportunistic or systemic infections)

27
Q

What probiotic does fortiflora contain?

Is it effective?

A

Enterococcus faecium SF68

effective in cats, but study did not show effectiveness in dogs (*few dogs had diarrhea issues)

28
Q

What probiotic does Prostora Max contain?

Is it effective?

A

Bifidobacterium animalis AHC7

A 2009 study showed a significant reduction in mean time to resolution in dogs with acute diarrhea treated with this probiotic (3.9 days) versus placebo (6.6).

The product has been discontinued.

29
Q

What are symbiotics?

A

combinations of prebiotics and probiotics

30
Q
A

Gastroenterology (11 decks)

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