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Flashcards in Microbial Ecology of the Mouth Deck (15)
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what is the idea behind the human microbiome

Idea is that on your body there are lots and lots of living organisms everywhere


what is a microbe

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


what is a microbiome

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

Changes to the microbiome tend to related to changes from health to disease


what is a biofilm

a community of microbes that live together on a surface


how are microbes ubiquitous

There are millions of microbes per square inch on your body

Thousands of different species on the skin alone

Some thrive on dry patches on the elbow, others thrive in moist environments like the armpit

It is estimated that there are more microbes in your intestine than there are human cells in your body


is there more bacterial cells than body cells in the human body?

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


what is included in a microbiome

A microbiome includes all the micro-organisms in a particular ecosystem


what are the different ways in which microbiome can be used

The term is sometimes used to describe the community of micro-organisms in a particular place

Sometimes it is used to describe the total of the genetic material of the microorganisms in a particular ecosystem


where do the microbes come from in the body

Some microbes are native, normally found in the body

Some microbes are introduced, suddenly arriving at a new residence in the body


how do we acquire our resident flora?

1. 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)

2. From feeding
- The nature of the flora colonising the intestines changes depending on whether the baby is bottle or breast fed
- The oral cavity, skin, GI tract, respiratory, and urogenital system all continue to be colonised as contact with other humans continues)


what are the benefits of normal flora

1. Synthesise and excrete vitamins
- Vitamin K
- Vitamin B12

2. Prevent colonisation by pathogens
- Competing for attachment sites or for essential nutrients

3. May antagonise other bacteria
- The production of substances which inhibitor kill non-indigenous species (nonspecific fatty acids, peroxides, bacteriocins

4. Stimulate the development of certain tissues
- Ie intestines
- certain lymphatic tissues
- Capillary density

5. Stimulate the product 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


what does a faecal transplant do

Faecal transplant = assisted colonisation

Gut flora similar to donor within 14 days
Big change
Faecal transplants work - completely change the microbiome


what prevents microbes from surviving within the oral cavity

- saliva
- pH
- temperature
- immune system
- brushing and flossing teeth clears some built up biofilm
- oral antibiotics inhibit growth


what does symbiosis of microbes that are able to survive in the conditions of the oral cavity do

form an elaborate scaffold that lives on the tooth enamel and at the interface with the gums.

It forms a barrier for incoming bacteria


what is Koch's Postulates

The germ theory of disease
• 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
• No absolute way to demonstrate Koch's Postulates in the oral cavity