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3rd yr- IWB- Microbiology > The Human Microbiome > Flashcards

The Human Microbiome Flashcards

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1
Q

Define the human microbiome

A

Microbes (including their genes and genomes) that li in and one the human body

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2
Q

Define resident microbiota

A

Organisms found in a given location in a state of health

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3
Q

Define colonisation

A

Establishment at a site in the body

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4
Q

Define symbiosis

A

Two or more organisms co existing in close association

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5
Q

Define opportunistic bacteria

A

Caused by an organism that is a member of the normal microbiota or normally inhabits the external environment

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6
Q

Define symbiotic association

A

Close relationships between two dissimilar organisms

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7
Q

list the 3 aspects that make up symbiotic associations

A
  1. Parasitism
  2. Commensalism
  3. Mutualism
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8
Q

What is mutualism?

A

An association between two organisms in which both species benefits

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9
Q

What is commensalism?

A

When one member of the relationship benefits and the other is unharmed/ unaffected

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10
Q

What is parasitism?

A

When on ember of the relationship benefits but is causing harm to the other

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11
Q

Which of the 3 types of symbiotic relationships do we usually have with our microbiome

A

A mix of commensalism and mutualism

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12
Q

How do we maintain a beneficial environment with our microbiome

A

There is continual pressure on our HOST IMMUNITY CELLS to maintain the beneficial relationship

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13
Q

What is dysbiosis

A

Imbalances in the resident human microbiota or our responses to them

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14
Q

Name the 3 types of detrimental relationships we can have with microbiota

A
  1. Predation/ parasitism
  2. Amensalism
  3. Competition
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15
Q

What is predation/ parasitism

A

When the host is infected

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16
Q

What is amensalism

A

When either the microbes or host are injured

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17
Q

What is competition

A

The struggle for resources

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18
Q

Define symbiont

A

Member of the resident microbiota that confers benefit to the host

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19
Q

Define pathobiont

A

A member of the resident microbiota that causes disease when loss of the normal balance between the host and resident microbiota occurs

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20
Q

How is a sterile site defined?

A

Defined as a site with no microbes present

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21
Q

How is a non sterile site defined

A

Non sterile sites are defined as having a normal microbial population due to their exposure to the environment

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22
Q

Why can non sterile sites in the body not become sterile?

A

As there’s no mechanical in place to maintain or re establish sterility

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23
Q

Give examples of non sterile sites

A
  1. Conjunctiva
  2. Oral cavity and oropharynx
  3. Vagina
  4. Skin
  5. GI tract
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24
Q

Name the different types of sterile sites

A

Sterility maintained by:

  1. Surface cleaning
  2. Barriers that allow uni directional flow
  3. Physical separation from non sterile sites
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25
Q

Give examples of sites in the body where sterility is maintained by surface cleaning

A

Lower respiratory tract

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26
Q

Give examples of sites in the body where sterility is maintained by barriers that allow uni directional flow

A
  1. Hepatobiliary tract
  2. Middle ear
  3. Upper genital tract
  4. Urinary tract
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27
Q

Which barrier maintains the sterility of the hepatobiliary tract

A

Sphincter of Oddi

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28
Q

Which barrier maintains the sterility of the middl ear

A

Eustachian tube

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29
Q

Which barrier maintains the sterility of the upper genital tract

A

Cervix

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30
Q

Which barrier maintains the sterility of the urinary tract

A

Urethra

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31
Q

Give examples of sites in the body where sterility is maintained by physical separation from non sterile sites

A

Closed cavities such as:

  1. Pleural cavity
  2. Peritoneal cavity
  3. Spinal cord and meninges
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32
Q

Where can microenvironment grow?

A

Between sites

Within sites

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33
Q

What factors effect where micro organisms can grow?

A
  1. Tissue tropisms
  2. Moisture
  3. Temperature
  4. pH
  5. O2 availability
  6. Nature of surface
  7. Surface turnover
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34
Q

What is tissue tropism

A

The propensity for a particular organism to grow in a particular habitat

35
Q

Describe the environment on our skin

A
  1. Variable temperatures
  2. Dry
  3. Subject to abrasion
  4. Aerobic environment
  5. Nutrient poor
  6. Skin surface components
36
Q

Describe the environment in gingival crevices

A 
1. Constant temperature 
2, Moist 
3. Inaccessible low fluid flow
4. Anaerobic environment 
5. Bathes in nutrients
37
Q

Where can micro environments form in the skin

A
  1. Toe webs
  2. Scalp
  3. Palms
  4. Axillae
38
Q

Where can micro environment form in the mouth

A
  1. The tooth surface
  2. Lingual surface
  3. Buccal surface
  4. Gingival crevice
39
Q

Where can micro environment form in the nasopharynx

A
  1. Tonsillar crypts

2. Nasal mucosa

40
Q

Where can micro environments form in the GI tract

A
  1. Stomach
  2. Small bowel
  3. Large bowel
41
Q

Which site of the body hosts the largest amount of micro organisms

A

The large intestine (10^9-10^11)

42
Q

Name the main taxon of species found on the skin

A

Staphylococci (particularly staphylococcus aureus)

43
Q

Name the early colonisers in the oral cavity

A

Virdans/ oral streptococci

44
Q

Name the most common microorganism found in the nostrils

A

S aureus

45
Q

List the most common microorganisms found in the pharynx

A
  1. Streptococcus pyogenes
  2. Haemophilus influenzae
  3. Streptococcus pneumoniae
  4. Staphylococcus aureus
46
Q

Describe the distribution of micro organisms in the small intestine

A

The number of micro organisms increases distal

pH in the GI tract is low which inhibits bacterial growth

47
Q

Describe the micro organisms found in the small intestine

A

Predominantly facultatively anaerobic bacteria

Very few or no obligate anaerobes

48
Q

Which intestine has more micro organisms small or large

A

Large (has around 10^9-10^11 organism per gram)

49
Q

How many species of microorganisms have been identified in the large intestine

A

At last 400

50
Q

How can the resident microbiota of the gut be destroyed or harmed?

A

By taking antibiotics

51
Q

When does the micro biota of the vagina change?

A

Post puberty

52
Q

Describe the microbiota of the vagina PRE puberty

A

Similar to the skin flora and lower GI microbiota

53
Q

Describe the microbiota of the vagina post puberty

A

A lot of lactobacillus species found

54
Q

Why does the microbiota of the vagina change post puberty

A

Due to circulating oestrogen producing glycogen

55
Q

What is the role of lactobacillus species in the vagina post puberty

A

It ferments glycogen which helps to maintain the pH at 3 and prevent the overgrowth of other bacterial species

56
Q

What are the main benefits of the resident human microbiota?

A
  1. Competitive exclusion of exogenous pathogens
  2. Antagonism of exogenous pathogens
  3. Promotes normal development of immune system
  4. Promotes normal human cellular physiology and nutrition
  5. Enteric bacteria secrete nutrients like vitamin K and B12
  6. Epithelial barrier function, cellular proliferation and wound healing repossess are improved
  7. Potentially protective cross reactive antibodies are induced
  8. Immunity is modulated to prevent chronic over stimulation
57
Q

What is an opportunistic infection?

A

An infection caused by an organism that is a member of the normal microbiota or normally inhabits the external environment

58
Q

Give examples of when an opportunistic infection can arise

A
  1. When epithelium is damaged
  2. In the presence of a foreign body
  3. If micro organism is transferred to other sites of the body
  4. If the immune system is suppressed/ disturbed
  5. If the normal microbiota is disturbed
  6. If host responses are impaired by exogenous pathogens
59
Q

Give examples of opportunistic infections

A
  1. Vaginal thrush
  2. Otitis media
  3. Conjunctivitis
  4. Urinary tract infection
  5. Peritonitis
  6. Intravascular catheter infection
  7. Caries
60
Q

What causes vaginal thrush

A

Caused by disruption of the normal microbiota of the vagina

61
Q

Give some signs and symptoms of vaginal thrush

A

Development of vaginal itch with creamy vaginal discharge

62
Q

How is vaginal thrush treated?

A

With broad spectrum antibiotics for sinusitis

63
Q

What causes otitis media

A

Translocation of bacteria from one site to another due to surface spread

64
Q

What causes conjunctivitis

A

Translocation of bacteria from one site to another due to surface spread

65
Q

What does otitis media affect?

A

The ear drum (ear ache with cough and runny nose)

66
Q

Give some signs and symptoms of conjunctivitis

A

Red eyes and purulent conjunctival discharge with cough and runny nose

67
Q

What causes urinary tract infection

A

Translocation of bacteria from one site to another due to surface spread

68
Q

Give some signs and symptoms of urinary tract infection

A

Urinary frequency and dysuria for 3 days

69
Q

How is a UTI treated

A

With oral trimethoprim

70
Q

What causes peritonitis?

A

Translocation of micro organisms from one site to another due to disease progression/ tissue damage
Usually due to perforated appendix

71
Q

What causes Intravascular catheter infection ?

A

Translocation of micro organisms from one site to another due to disease progression/ tissue damage

72
Q

Give examples of micro organisms that can cause caries

A
  1. Streptococcus mutants
  2. Lactobacillus species
  3. Actinomyces species
73
Q

Give examples of micro organisms that cause periodontal disease

A
  1. Porphyromonas gingivalis
  2. Tannerella forsythia
  3. Aggregatibacterium
  4. Actinomyces
  5. Spirochaetes
74
Q

Give examples of micro organisms that cause aspiration pneumonia

A

Staphylococcus species and some other anaerobes

75
Q

Give examples of micro organisms that cause infective endocarditis

A

Alpha haemolytic streptococci

Staphylococcus species

76
Q

Give examples of micro organisms that cause abscesses

A

Streptococcus

Actinocmyces speices

77
Q

Give examples of micro organisms that cause candidiasis

A

Candida species

78
Q

Give examples of disease that can be caused by resident microbiota if the environment of the host changes

A
  1. Caries
  2. Periodontal disease
  3. Infective endocarditis
  4. Aspiration pneumonia
  5. Abscesses
  6. Candidasis
79
Q

How can cross infection lead to the development of an opportunistic infection

A

As the resident microbiota may be harmless in one person but dangerous in another

80
Q

Give examples of opportunistic infections caused by crossing infection

A
  1. Methicillin resistant S aureus (MRSA)
81
Q

What is MRSA

A

Methicillin resistant S aureus (a superbug)

82
Q

How can we diagnose and identify opportunistic infections

A

By carrying our non culture based tests

83
Q

Name the 6 classes of antimicrobial resistant phenotypes

A
  1. Phenicol
  2. Sulphoamide
  3. Lincosamide macrolide streptogramin
  4. Aminoglycoside
  5. Tetracycline
  6. Beta lactam

3rd yr- IWB- Microbiology (12 decks)

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