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20 Cards in this Set
- Front
- Back
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probiotics |
live microorganisms which when administered in adequate amounts confer a health benefit on the host |
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prebiotics |
dietary substances that nurture a selected group of microorganisms living in the gut -favour growth of beneficial bacteria over harmful bacteria |
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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 |
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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 |
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mechanism of probiotic/host interaction |
Theory 1: restore balance to intestinal flora Theory 2: anti-microbial effects Theory 3: stimulate immune fxn |
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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) |
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theory 2: antimicrobial effects |
-produce substances (lactic/acetic acid, peroxides, or bacteriocins (toxins)) to block colonization of pathogens |
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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 |
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properties of an ideal probiotic |
-high adherence to intestinal wall -stable against gastric acid, bile, oxygen & enzymes -nonpathogenic -able to co-aggregate as part of the natural gut flora -resistant to the effects of an abx -evidence for a health benefit |
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main microorganisms used in probiotic formulation |
Lactobacillus Bifidobacteria Saccharomyces |
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Lactobacillus |
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 |
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Bifidobacteria |
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 |
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saccharomyces boulardii |
a nonpathogenic yeast -mostly colonize in the colon -believed to be a strain of Saccharomyces cerevisiae (baker's yeast) |
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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 |
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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 (?) |
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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 |
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efficacy in IBS |
fairly positive evidence for treating overall sx and abdominal pain in IBS -supporting evidence for B. infantis 35624 |
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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 |
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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 |
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adverse effects |
-very well tolerated common SE: -transient: bloating, diarrhea, abdominal discomfort may down-regulate immune fxn in immunocompromised pts -best to avoid |
