Oral Ecology Flashcards by niamh ritchie

microbe

tiny living organism, such as bacterium, fungus, protozoan, or virus

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microbiome

collectively all the microbes in the human body; a community of microbes

living in synergy or antagonism

changes related to changes in health and disease

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biofilm

a community of microbes that live together on a surface

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factors which the oral cavity a good incubator for microbes

moist

warm

fed frequently

usually stable - can change due to diet etc

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how do bacterial cells outnumber body cells

Bacterial cells outnumber your body cells 10:1 and comprise up to 4-6 lbs of your body mass

We are a vehicle for microorganisms
- They have greater control of us
Live in synergy, they influence us

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what does a microbiome include

A microbiome includes all the microorganisms in a particular ecosystem.

The term is sometimes used to describe the community of microorganisms in a particular place.
(If not multiple – gingival crevice, dorsal of tongue, cavity/carious lesion, denture)

Sometimes it is used to describe the total/sum of the genetic material of the microorganisms in a particular ecosystem.
- Genetic material has many sources – inflammatory cells, host cells etc

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2 meanings of microbiome

The term is sometimes used to describe the community of microorganisms in a particular place.
(If not multiple – gingival crevice, dorsal of tongue, cavity/carious lesion, denture)

Sometimes it is used to describe the total/sum of the genetic material of the microorganisms in a particular ecosystem.
- Genetic material has many sources – inflammatory cells, host cells etc

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what does microorganisms and humans/animals being holobiant imply

Synergy between microorganism plants and simple animals

Evolve convergently not divergently
- Everchanging

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2 states microbes can be to the human body

native

introduced

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introduced microbes are

Suddenly arriving at a new residence in the body

- With time and age

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how does the GIT microbial community assemble

From delivery: The gut flora of vaginally-delivered babies differs from babies delivered by C-section
- The vaginal microbial community of pregnant women contains bacteria involved in digesting milk (Lactobacillus)

From feeding: The nature of the flora colonizing the intestines changes depending on whether the baby is bottle- or breast-fed

The oral cavity, skin, gastrointestinal tract, respiratory, and urogenital system all continue to be colonized as contact with other humans continues

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what influences how MO species disperse/established in the body

Species traits can influence the probability of both dispersal/establishment, as well as how they fare in competition and other species interactions.

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trait of lactobacillus that favours it

Excludes many pathogens as it metabolises sugar to acid

- Almost protective

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what is the main influence on the microbial community in the gut

diet

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is the microbial environment same across the body

All different compositions

important changes in compositions at different locations on body
able to stratify populations

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5 benefits of normal flora

Synthesize and excrete vitamins
- Vitamin K and Vitamin B12

Prevent colonization by pathogens
- competing for attachment sites or for essential nutrients

May antagonize other bacteria
- the production of substances which inhibit or kill non-indigenous species (nonspecific fatty acids, peroxides, bacteriocins).

Stimulate the development of certain tissues

i.e., intestines, certain lymphatic tissues, capillary density
benefit to immune system and physiology
—no microorganisms can lead to malnourishment and being sensitive to external stresses

Stimulate the production of cross-reactive antibodies.

Low levels of antibodies produced against components of the normal flora are known to cross react with certain related pathogens, and thereby prevent infection or invasion.
Tolerance to immune stimulus is dictated by type you have

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how can the fact normal flora helps stimulate some tissues development be beneficial to us

benefit to immune system and physiology

-no microorganisms can lead to malnourishment and being sensitive to external stresses

can microbiomes between different individuals be the same

some can show functional similarity (e.g. twin and twin, twin and mum)

what is a fundamental key role of bacteria and parasites in digestion

Generally, things are not metabolically processed

Bacteria fungi do and then we absorb side products

what can faecal transplant do to the microbiome

Can modulate microbiome back to health from completely dysbiotic

what is the effect of dieting on the microbiome in GIT

Change the microbiome
Train gut to have more Bacteroidetes than firmicutes
- change composition

that increased numbers of Bacteroidetes bacteria correlate with weight loss
- Leaner

Shifting the relative abundances of the microbiota is changing the function of the community in a way that has an impact on the host.

what could potentially be an additional function of the gut microbiome composition that could impact health

Energy extraction efficiency could be a function of the gut community composition

Sum of the function is more important than what is present

the obese microbiome could harvest more energy from the diet.
the amount of energy gained from a packet of cereal for example may be a function of the mix of microbes in the gut.

what is the main way to measure the work of a microbiome

Sum of the function is more important than what is present

describe the general composition of the oral cavity microbiome

60-70 different microorganisms in each individual

Combinations determine oral disease along with oral hygiene and host immunity

what is the main role of the oral microbiome in health

Symbiosis of the oral microbes that are able to survive these conditions form an elaborate scaffold that lives on the tooth enamel and at the interface with the gums. forms a barrier for incoming bacteria. Small amount of plaque can keep in balance - stressed, immune compromised, over brushed

how can bacteria in mouth drive inflammatory disease

Bugs in mouth can drive inflammatory disease Not specific. It’s the sum of function - Don’t get mono-species infection - mixture is responsible

what is a basic prevention of inflammatory disease from oral cavity

oral hygiene instruction

what are the 4 elements of Koch's Postulate

The microbe must be present in every case of the disease The microbe must be isolated from the diseased host and grown in pure culture The disease must be reproduced when a pure culture is introduced into a susceptible host The microbe must be recovered from an experimentally infected host

why does Koch postulate not apply to the oral cavity microbiome

Not one organism (mono-species) Can show associations and correlations - Periodontitis – P.gingivalis link

is the oral microbiome constant throughout

no Intra-Oral Variation - Depending on where you sample - Different pattern of microbiota

what do 'bad' microorganisms cause

dysbiosis leads to ecological change

what is the impact of having a high sucrose diet on oral ecology

drive acid producing organisms if left unbrushed and unchecked

how can starch impact the oral microbiome

slow release stick on teeth leads to same building blocks of sucrose thus leading to caries

what is the potential harm of nitrites and proteins on the oral microbiome

But proteins and nitrites may induce the production of HA and enamel but also sulphur compounds - Periodontal problems - Mal odour balanced diet is key

what can any microbial change in the oral cavity lead to

dysbiosis | - lasting change that may not be recoverable

what is the job of prebiotics

feed microbiome of particular nutrients can be more effective

4 effects of antibiotics

selection for intrinsically resistant bacteria selection for new mutations and gene transfers conferring resistance depletion of bacterial diversity altered gene expression , protein activity and overall metabolism

impact on host of having gut microbiota - loss of potential competitors, - lower expression of antibacterials and IgG, - decrease of neutrophil-mediated killing

increase susceptibility to infections leading to infection by exogenous pathogens or by opportunistic members of the microbiota

impact on host of having gut microbiota - establishment of resistance bacteria - transfer of resistance genes to pathogens

accumulation of antibiotic resistances leading to untreatability of bacterial infections

impact on host of having gut microbiota - elevated inflammatory tone - altered insuline sensitivity - altered metabolism of SCFA and bile acids

deregulated metabolism leading to obesity, metabolic syndrome and diabetes

impact on host of having gut microbiota - disruption of Treg/Th balance - elevated inflammatory tone

compromised immune homeostasis leads to atopic, inflammatory and autoimmune disease (allergies, asthma, necrotising enterocolitis, inflammatory bowel disease, irritable bowel syndrome etc)