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20 Cards in this Set

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


dietary substances that nurture a selected group of microorganisms living in the gut

-favour growth of beneficial bacteria over harmful bacteria

eg of prebiotics

fermentable carbs:

-oligofructose, inulin, galacto-oligosaccharides, lactulose

-found in cookies, cereals, chocolate, dairy products

eg: fermentation of oligofructose in colon

--> increase # of bifidobacteria

--> increase calcium abs

--> increase fecal weight

--> shortening of GI transit time

probiotic uses

-prevent and treat conditions caused by pathogenic bacteria (tx and prevention of AAD, acute infectious diarrhea)

-eradication of H pylori

-boost immune response

-prevent URTIs

-improve IBD and IBS

-improve lactose intolerance

-decrease cholesterol

-assist in weight loss

mechanism of probiotic/host interaction

Theory 1: restore balance to intestinal flora

Theory 2: anti-microbial effects

Theory 3: stimulate immune fxn

Theory 1: restore balance to intestinal flora

-counteract disturbances by recolonizing the intestine and crowding out 'bad' bacteria

-compete for adhesion helping to enhance epithelial barrier (help w mucous production)

theory 2: antimicrobial effects

-produce substances (lactic/acetic acid, peroxides, or bacteriocins (toxins)) to block colonization of pathogens

theory 3: stimulate immune fxn

-enhance Ab production and natural killer cell activity; alter cytokine release

-improve phagocytic activity

*only in healthy individuals; not people w immune system hypersensitivity

properties of an ideal probiotic

-high adherence to intestinal wall

-stable against gastric acid, bile, oxygen & enzymes


-able to co-aggregate as part of the natural gut flora

-resistant to the effects of an abx

-evidence for a health benefit

main microorganisms used in probiotic formulation





G+ rods, anaerobes

-able to survive gastric conditions better than bifidobacteria

-do not require enteric coating

-can latch onto intestinal wall for _> 1w

-lactic acid producing

-used to ferment milk to make yogurt

-aka Acidophilus


G+, anaerobes

-mostly colonize in the colon

-appear to be the most important organism in intestine for providing a microbial barrier to infection

-also a lactic acid bacteria

-predominant intestinal flora of breast-fed infants

saccharomyces boulardii

a nonpathogenic yeast

-mostly colonize in the colon

-believed to be a strain of Saccharomyces cerevisiae (baker's yeast)

Abx-associated diarrhea (AAD)

occurrence: 1-44%

-caused by disruption of gut microbiota caused by abx therapy

-episodes range from mild (stopping when abx stop) to serious (bowel perforation, death)

increased risk w:

-age, co-morbidity, broad spectrum abx, length of tx

efficacy in AAD

-evidence supports use of S. boulardii and L. rhamnosus GG

-insufficient evidence to rate: Bifidobacteria

more effective at higher doses?

_> 50 billion cfu/d

take for same duration as abx

-space doses by 2h

-continue 1-2w after d/c abx (?)

efficacy in CDAD

evidence positive

-specific strain, length of tx, safety in immunocompromised not known

L. rhamnosus, LGG (Culturelle) most often used

some evidence for S. boulardii

doses used: at least 10 billion organisms/d

efficacy in IBS

fairly positive evidence for treating overall sx and abdominal pain in IBS

-supporting evidence for B. infantis 35624

efficacy in prevention of acute URTI

better than placebo at reducing # episodes and duration (0.4 of a day) -CS??

-quality of evidence is very LOW

most studied was Lactobacillus (different spp. & strains)

-most given w milk-based food

-doses used: 10^9 or 10^10 CFU/d

yogurt vs NHP?

available in fermented dairy foods

-stability is an issue (should be refridgerated)

-some yogurts contain encapsulated powdered bacteria

-short shelf life

pharmaceutically based delivery systems are more reliable

adverse effects

-very well tolerated

common SE:

-transient: bloating, diarrhea, abdominal discomfort

may down-regulate immune fxn in immunocompromised pts -best to avoid