MFD11 Diseases as an imbalance of microbes

Question 1

Give an example of a common condition caused by dysbiosis of microbial community in the gut:

Answer 1

Irritable bowel disease (IBD)

Question 2

What laboratory tool is used to test koch’s postulate 1 (The suspected pathogen must be present in all cases of the diseases and absent from healthy animales)

Answer 2

microscopy and staining

samples taken from a diseased animal and a healthy animal

Question 3

What laboratory tool is used to test koch’s postulate 2
(The suspected pathogen must be grown in pure culture (after being isolated from diseased host))
2) What would be observed?

Answer 3

laboratory cultures: This involves streaking agar plate with sample from diseased animal,
2) then you will observe colonies of suspected pathogen.

Question 4

What laboratory tool is used to test koch’s postulate 3
(the suspected pathogen from the pure culture must cause the disease in a healthy animal
2) What would be observed?

Answer 4

Experimental animals :
inoculate a healthy, susceptible laboratory animal,
2)observe inoculated animal becomes diseased

Question 5

What laboratory tool is used to test koch’s postulate 4

the pathogen must be reisolated from the new host and shown to be the same as the originally inoculated pathogen

Answer 5

Laboratory reisolation and culture:
remove a blood or tissue sampla and observe by microscopy, the culture,
2) Observe:
Pure culture is the same organism as before

Question 6

RECAP: what are the 4 koch’s postulates:

Answer 6

• The organism must be present in all cases of disease, and not present in healthy individuals
• The organism must be isolated in pure culture
• The isolated organism must cause disease in a suitable animal
• The organism must be re-isolated from infected animal

Question 7

Give 3/5 resasons why Koch’s postulate cannot be applied:

Answer 7

• If the bacteria cannot be grown in culture
• If no infecting organism can be detected
• If no suitable animal model is available
• If more than one species of bacterium is involved
• If it is the level rather than just the presence of the infecting bacterium that is important

Question 8

1) what does OUT stand for?
2) What is it?
3) What does it let you observe?

Answer 8

1) oxonomic taxanomic unit, basically
2) means species,
3) only lets you look at bacteria

Question 9

What extra reading would you take if you wanted to see viruses present as well when doing DNA sequencing?

Answer 9

shotgun reading

Question 10

Why are we able now to collect data on complex microbial populations?

Answer 10

1) Advances in DNA sequencing

Question 11

What gene is sequenced in targeted microbiome analysis for bacteria?
2) Why?

Answer 11

1) 16S rRNA gene

2) Conserved area

Question 12

What does metagenomics involve ?

Answer 12

sequencing all DNA

present in a sample, then using bioinformatics

to predict the source/function of the DNA

sequences

Question 13

Depending on __1__ you sample in the __2__ there is big differences in what organisms are present.

Answer 13

1) where

2) body

Question 14

1) how many species are present in the gut microbiome?

2) Are there differences in the no. of species between people?

Answer 14

1) lots and lots , one of the most diverse areas in the body
over 300
2) yes, more difference than in oral microbial communities

Question 15

What type of gut microbiota are essential for development of a healthy immune system?

Answer 15

commensal gut microbiota

Question 16

What are the differences in the microbiota between individuals associated with:

Answer 16

• Obesity
• Colorectal cancer
• Inflammatory bowel disease
• Many systemic conditions (though links are often less clear cut).

Question 17

What is New-onset Paediatric Crohn’s Disease?

HINT: mention what occurs due to bacterial dysbiosis

Answer 17

Is a type of inflammatory bowel disease, the microbiome dysbiosis leads to a drop in bacterial populations with similar metabolic reactions thus genes are missing that are required fro certain metabolic pathways.

Question 18

How many people are affected by Crohn’s disease and ulcerative colitis?

Answer 18

over 3.6 million (incidence is on the rise)

Question 19

What factors are involved in development of Inflammatory bowel disease?

Answer 19

Host genetics play a key role, but <50% concordance between monozygotic twins. Therefore, not just about host genetics.
Gut microbiome is gaining increasing attention and what environmental factors effect that

Question 20

What conditions are encompassed by inflammatory bowel disease (IBD)?

Answer 20

Crohn’s disease and ulcerative colitis

Question 21

what environmental factors effect gut micriobiome (thus amy cause IBD)

Answer 21

genetics, birth route, lattitude, hygiene, stress, diet/nutrition, drugs (antibiotics)

Question 22

Define perturbation:

Answer 22

deviation of a process from regular path

Question 23

What 3 effects does a healthy gut micobiome have on the body (complex and stable)?

Answer 23

1) protect against pathogens
2) train/stimulate immune function
3) supply nutrients, energy, vitamins and SCFA (short-chain fatty acids)

Question 24

What 5 effects does a unhealthy gut micobiome have on the body (disease state)?

Answer 24

1) Inflammation (more local than systemic)
2) ocidative stress
3) increase in gram-negative bacteria (REMEBER disease can be the right organisms at the wrong levels as well as the wrong organisms)
4) infection (opportunistic/pathogenic)
5) altered metabolite production

Question 25

What are the 2 methods employed to target the microbiome and treat dysbiosis?

Answer 25

1) Careful selection of antibiotics to minimise unwanted shifts in the microbiota
2) Repopulation of the gut with healthy bacteria

Question 26

Give 3 examples of Repopulation of the gut with healthy bacteria to treat microbiome dysbiosis:

Answer 26

1) Prebiotics (You rely on the healthy bacteria being there still and you feed them)
2) Probiotics (live yogurts, full of good bacteria- atm not regulated yogurt companies just feed you bacteria you don’t even know if it will reach the gut)
3) Faecal microbiota transplantation (encouraging results for relapsing C. diff. infection but not so clear for IBD).= microbiome restored (sometimes)

Question 27

Give an example of careful selection of antibiotics to minimise unwanted shifts in the microbiota to treat microbiome dysbiosis:

Answer 27

E.g. avoid repeated use of a single antibiotic

Question 28

2 Major dental plaque-related diseases:

Answer 28

• Dental caries

* Periodontitis.

Question 29

What is the Specific plaque hypothesis

Answer 29

diseases are caused by a single microorganism.

Question 30

What is the Non-specific plaque hypothesis:

Answer 30

diseases are caused by the amount of plaque.

Question 31

What is the Ecological plaque hypothesis:

Answer 31

disease is caused by
interactions of specific microorganisms with the
microbial community

Question 32

What bacteria is elevated in caries and though to cause it?

Answer 32

S.Mutans

Question 33

Why does demineralisarion occur?

minus the chemistry side- don’t forget critical pH an dissolution values

Answer 33

1) a stress e.g. acid production
2) pH lowered ( acidic)
3) ecological shift bacterial population changes (more S.mutans, Lactobacillusspp. scardovia wiggsiae)
4) demineralisation occur

Question 34

Describe the progression to cavitiation of teeth (surface errosion):

Answer 34

1) health
2) subsurface demineralisation
3) White spot lesion (still reversible)
4) cavitation (not reversible)

Question 35

In the Extended Caries Ecological Plaque Hypothesis, what bacteria are present in the dynamic stability stage ( net mineral gain, lesion regression/arrest):

Answer 35

dominance of non-MS actinomyces

Question 36

What is actinomyces?

2) What does it do with streptococci in the oral cavity?

Answer 36

1) a genus of the Actinobacteria class of bacteria. They are all gram-positive.
2) form a fundamental component of the indigenous microbiota, being among initial colonizers in polymicrobial biofilms. They can adhere
to surfaces such as on teeth and to co-aggregate with other bacteria.

Question 37

In the Extended Caries Ecological Plaque Hypothesis, what bacteria are present in the acidogenic stage ( roughly no mineral gain or loss):

Answer 37

“low -pH” non-MS and Actinomyces

Question 38

In the Extended Caries Ecological Plaque Hypothesis, what bacteria are present in the acidoduric stage ( net mineral loss):

Answer 38

increase in MS and non-mutans aciduric bacteria

Question 39

What are the 3 stages in the extended caries ecological plaque hypothesis? (from good to bad)

Answer 39

1) dynamic stability stage
2) acidogenic stage
3) Aciduric stage

Question 40

What is the keystone pathogen idea in periodontitis development?

Answer 40

The idea there is a key pathogen driving caries however it doesn’t ever have a high population.

Question 41

What is the suggested hypothesis of how P,gingivalis is a keystone pathogen?

Answer 41

1) It produces ginigpain
2) gingipain binds to TLR of immune cells
3) resulting in inflammation and impaired leukocyte killing
4) allowing without changes in its population to manipulate the populations of microbiota
5) Inflammation also causes complement-dependent and bone loss

Question 42

What is the polymicrobial synergy and dysbiosis (PSD) model of periodontal disease

Answer 42

Periodontitis is initiated by a synergistic and dysbiotic microbiota, within which different members, or specific gene combinations thereof, fulfil distinct roles that converge to shape and stabilize a disease-provoking microbiota.

Question 43

What possible roles will polymicrobial synergy play in the polymicrobial synergy and dysbiosis (PSD) model of periodontal disease:
(DO NOT NEED TO MEMORISE JUST comprehend what the role of ps is in disease progression)

Answer 43

it arises due to
interspecies interactions within the cariogenic community and interactions include:
1) one organism providing a substratum for the attachment and colonization of another,
2) nutritional cross feeding, and the co-ordinated metabolism of complex substrates
3) physical interactions & diffusible soluble factors could modulate virulence gene expression

Question 44

Does polymicrobial synergy only occur in cariogenic communties?
2) In cariogenic communties which populations of bacterai are involved>

Answer 44

1) Synergistic interactions also occur in the healthy state but between commensal bacteria.
2) In cariogenic communities, synergistic interactions occur between acidogenic and aciduric bacteria during the different stages of biofilm development and acidification,

Question 45

Define:

acidogenic bacteria

Answer 45

Producers of acid from fermentable carbohydrates, found in dental biofilm (q.v.); may be related to caries development.

Question 46

Define:

aciduric bacteria

Answer 46

The aciduric group of bacteria consists of those micro-organisms that are able to live and multiply in degrees of acidity unfavorable for the development of most microbes.