Extenta Jan 2023 Flashcards
Dysbiosis and Diversity are two terms that are often used when discussing the microbiota.
Explain the terms in detail and describe the importance of them in human health.
Dysbiosis is an imbalance in the microbiome
Diversity is a measure of how many different species of bacteria are present
The bacterial taxonomy uses hierarchical levels for classification. Choose three species (of
relevance within the topics intestinal microbiota and probiotics) belonging to different classes
and name them for all levels accordingly (from phyla to species), in the correct order and
starting with the highest level. Also use upper- or lower-case letters and italics in the correct
context.
Firmicutes
Bacilli
Lactobacillales
/Lactobacillacea
/Lactobacillus
/L. acidophilus
Proteobacteria
Gammaproteobacteria
Enterobacteriales
/Enterobacteriacea
/Eschericia
/E. coli
Actinobacteria
Actinobacteriia
Bifidobacterilales
/Bifidobacteriacea
/Bifidobacterium
/B. bifidum
You are going to design a clinical trial to prove that probiotics can prevent diseases. Choose
one disease or syndrome that have been discussed during the course or is mentioned in the
compendium Probiotics (Molin G., 2022).
a) Describe the study design you have chosen and suggest suitable endpoints for the trial.
Motivate your answer.
b) Suggest one suitable probiotic species for the trial and explain how it can prevent the disease
that you have chosen.
c) Describe in detail the method you would have chosen for analysing the presence of the
probiotic species in the gastrointestinal tract.
d) Describe whether there is a risk of side effects from the probiotics you have chosen for the
individuals you want to give it to, as a preventive measure to reduce the risk of disease
development.
IBD would be an interesting disease from a probiotics viewpoint.
a) Randomised controlled trial. Two groups. One receives probiotics and the other a placebo. Endpoints for the trial would be a change in pain level/discomfort/bowel movement/flatulence
b) Lactobacillus plantarum 299V
c) Sanger sequencing using specific primers
d) There shouldn’t really be any risks, only that the first few days may feel a little different
Which are the typical dominating Gram-negative, and Gram-positive phyla that can be found
frequently in the intestinal tract of healthy human individuals? Name two Gram-negative and
one Gram-positive phyla.
Bacteroidetes (gram negative)
Proteobacteria (gram negative)
Firmicutes (gram positive)
All Gram-negative bacteria have pro-inflammatory compounds associated to the cell wall,
what is it called?
LPS lipopolysaccharides contain lipid A which is an endotoxin
Describe shortly (processes and involved cells and organs) how an inflammatory process can
be initiated in the small intestine by the microbiota.
Peyer’s patches present in the small intestine and contain specialised epithelial cells called M cells that sample the intestine for antigens. Dendritic cells are also present in the peyers patches and can also sample. These antigens are presented to T cells. Turn T cells into regulatory T cells. M cells can transport antigens via transcytosis. Dendritic cells can stick their dendrites through epithelial cells to sample.
Long-term inflammation is a risk factor for several diseases, name three diseases.
Inflammatory bowel’s disease. Autoimmune diseases. Metabolic diseases such as type 2 diabetes.
T/F: Cytokines are always pro-inflammatory mediators.
False. Can also be anti-inflammatory
T/F: All strains from the same species will act the same way
False
Example
HEAL9 and 299V have different properties
T/F: Effects of probiotic treatments are dose-specific.
Need to be an adequate dose
T/F: Next generation sequencing is only detecting live cells.
False, it is about genetic material
T/F: Translocation is the passage of viable cells through the intestinal wall.
True
T/F: The genus Enterococcus but not Bifidobacterium are sometimes wrongly regarded as
LAB.
Enterococcus is a LAB but not bifidobacterium. So must be false.
T/F: Staphylococcus belongs to the phylum Firmicutes
True
T/F: Through phenotypic classification organisms are grouped together based on similar
observable characteristics.
True
T/F: Fermented plant-based products contain in general 10^5−7 lactic acid bacteria/ml or g
True
T/F: Lactobacillus plantarum is now named Lactiplantibacillus plantarum.
True
T/F: QPS in QPS list stands for Qualified Probiotic Species
No Qualitied Presumption of Safety
T/F: The 18S rRNA gene is used for identification of bacterial strains.
False, 16S for bacteria, 18S for yeast
T/F: Today there is non approved health claim on probiotic by EFSA.
No health claim specific to probiotics has been authorised in the EU
In principle, what is the difference between bacterial identification and bacterial
classification?
You classify based on the different characteristics you can identify.
Explain why the 16S rRNA gene is used for identification of bacteria?
Because it has both conserved and hypervariable regions
Describe one traditional lactic acid fermented food based on plant-material (name of product,
production process, microorganisms involved, and estimated bacterial concentration in the
final product)
Kimchi
Sauerkraut
Lactic acid bacteria
Estimated bacterial conc is between 10^5-7 for fermented foods.
Describe the concept transient microbiota (or variable microbiome) and reflect upon the
possibilities for the microorganisms in the fermented food mentioned in 7a, to affect the
composition of the gut microbiota after consumption.
The transient microbiome is passing through and not part of the core commensals but will still have an effect. Particularly if the probiotics is consumed regularly. While it may not colonise the gut it still has the potential to affect the composition of the microbiome.
