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Immunology > Lecture 21 - Microbiota And Human Health > Flashcards

Lecture 21 - Microbiota And Human Health Flashcards

1
Q

What is microbiota?

A

The microorganisms found associated with normal healthy people

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2
Q

Where is microbiota found?

A

Surface tissue - skin, gastrointestinal tract, respiratory tract, urogenital tract

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3
Q

What does microbiota vary with?

A

Age, diet and environment

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4
Q

Parasitism

A

One species lives at cost of other

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5
Q

Mutualism

A

Both species benefit

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6
Q

Commensalism

A

One species benefits without harm to other

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7
Q

What are microbial pathogens?

A

Parasites

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8
Q

What are normal flora often called?

A

commensals

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9
Q

Why does normal microbiota matter to clinicians?

A

Surgery breaks physical defences of body allowing normal flora into sterile sites Treatment damage normal immune defences, allowing normal flora to become opportunistic pathogens Isolation of potential pathogens for diagnosis dependent on distinction from normal flora Role of microbiota in health and disease

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10
Q

What are the benefits of microbiota?

A

Nutrition protection - “colonisation resistance” Maturation of the gut priming of the immune system

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11
Q

Nutrition

A

Breakdown of complex polysaccharides Production or useful metabolites e.g. vitamin K

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12
Q

Protection

A

Occupy niche to prevent access by pathogens produce bacteriocins to inhibit other species disruption of normal flora by antibiotic treatment can cause problems “thrush and pseudomembranous colitis”

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13
Q

Priming of the immune system

A

Presence of low level antibodies against normal flora may enhance immunity against pathogens Immune system abnormal in germ-free animals

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14
Q

What is the acquisition of the microbiota?

A

Microbiota acquired rapidly after birth, mostly from mother composition changes depending on age and environment Tests on individuals training for space flights show flora shared, become uniform

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15
Q

How to investigate the microbiota?

A

Culture bacteria from biopsy or faeces Apply molecular techniques

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16
Q

What is the cast of characters

A

Differences in: cell wall, surface antigens, secreted proteins, respiration, metabolites, genome sequence

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17
Q

How to identify species?

A

Use 16SrRNA genes Extract total DNA PCR with universal 16S primers Clone and sequence products.
Identify species present

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18
Q

What is the gut?

A

Highly anaerobic - organisms that have never been exposed which find that oxygen is toxic in nature - hard to culture

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19
Q

More related species have more similar what ?

A

Similar 16SrRNA gene sequence

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20
Q

What does sequence allow?

A

Identification of species

21
Q

What are new sequences assigned to?

A

genus or higher phyla

22
Q

What is next generation sequencing?

A

Takes an array and spreads them out on a glass dish so each spot has a sequence on it. Can be amplified in situ Sequencing can determine the sequence from each spot on this plate AKA massively parallel sequencing technologies

23
Q

Metagenomics

A

Extract total DNA Sequence fragments (cloned or direct).
Identify species present Identify metabolic functions encoded

24
Q

What is the diversity of human intestinal microbial flora?

A

3 individuals (great diversity) 6 sites in colon + stool (little diversity Total 12,000 sequence gave 395 phylotypes

25
Q

What is Bifidobacteria?

A

Used in yoghurts promoting health benefits

26
Q

What are the different types of skin flora?

A

Staphylococcus epidermis Staphylococcus aureus Propionibacterium acnes

27
Q

Staphylococcus epidermis

A

Abundant in skin surface Can cause infection, especially in people with medical devices

28
Q

Staphylococcus aureus

A

Found especially on most skin, not on everyone N.
Cause of serious infections of wounds, bone

29
Q

Propionibacterium acnes

A

Mainly within follicles (anaerobic) Associated with acne

30
Q

What are other species of skin flora?

A

Corynebacteria Diphtheroids Micrococci Yeasts

31
Q

Typically how many bacteria per follicle ?

A

10^4

32
Q

What are pungent body odour due to?

A

Skin commensals (corynebacteria) Partically abundant on areas of most skin and auxiliary hair

33
Q

What are the respiratory tract flora?

A

Nose Throat/nasopharynx Lower respiratory tract

34
Q

What does the carriage of pathogens include ?

A

N. Meningitidis S. Pneumonia

35
Q

Throat/nasopharynx

A

Streptococci Neisseria spp Anaerobic organisms

36
Q

What is the Gastrointestinal tract flora?

A

Mouth Stomach small intestine Large intestine

37
Q

Mouth

A

Very complex flora associated with different environments e.g. teeth, gums Organisms live in a biofilm (dental plaque)

38
Q

What do species of mouth depend on?

A

Each other as well as on host for production of nutrients and generation of anaerobic atmosphere

39
Q

Stomach

A

Low PH, essentially sterile H.pylori May be carried asymptomatically

40
Q

Small intestine

A

Relatively few bacteria

41
Q

Large intestine

A

Very large numbers Many species - anaerobes, coliform, enterococci

42
Q

What does inflammatory bowel disease represent?

A

Abnormal immune reaction to normal flora

43
Q

Probiotics marketed for improving normal flora

A

treat diarrhoea, antibiotic associated problems. Bifidobacteria and lactobacilli Efficacy still controversial

44
Q

Urogenital tract flora: male

A

Mainly skin flora

45
Q

Urogenital tract flora: females

A

Skin and gut flora until puberty then hormone production lead to lower PH favouring lactobacilli

46
Q

What does antibiotic treatment or contraceptive pill upset?

A

Normal balance and lead to yeast growth “thrush”

47
Q

Metabolomics

A

To look at bacterial products and metabolites Global analysis of small molecule Use GC/MS or NMR Currently being developed for diagnosis

48
Q

What is probiotics ?

A

A live microbial food ingredient that is beneficial to health

49
Q

What is probiotics ?

A

A dietary carbohydrate selectively metabolised by probiotic organism

Immunology (20 decks)

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