Oral Ecology Flashcards
microbe
tiny living organism, such as bacterium, fungus, protozoan, or virus
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
biofilm
a community of microbes that live together on a surface
factors which the oral cavity a good incubator for microbes
moist
warm
fed frequently
usually stable - can change due to diet etc
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
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
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
what does microorganisms and humans/animals being holobiant imply
Synergy between microorganism plants and simple animals
Evolve convergently not divergently
- Everchanging
2 states microbes can be to the human body
native
introduced
introduced microbes are
Suddenly arriving at a new residence in the body
- With time and age
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
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.
trait of lactobacillus that favours it
Excludes many pathogens as it metabolises sugar to acid
- Almost protective
what is the main influence on the microbial community in the gut
diet
is the microbial environment same across the body
no
All different compositions
- important changes in compositions at different locations on body
- able to stratify populations
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
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)
