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

The Human Microbiome Flashcards

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
Give examples of sites in the body where sterility is maintained by surface cleaning
Lower respiratory tract
26
Give examples of sites in the body where sterility is maintained by barriers that allow uni directional flow
1. Hepatobiliary tract 2. Middle ear 3. Upper genital tract 4. Urinary tract
27
Which barrier maintains the sterility of the hepatobiliary tract
Sphincter of Oddi
28
Which barrier maintains the sterility of the middl ear
Eustachian tube
29
Which barrier maintains the sterility of the upper genital tract
Cervix
30
Which barrier maintains the sterility of the urinary tract
Urethra
31
Give examples of sites in the body where sterility is maintained by physical separation from non sterile sites
Closed cavities such as: 1. Pleural cavity 2. Peritoneal cavity 3. Spinal cord and meninges
32
Where can microenvironment grow?
Between sites | Within sites
33
What factors effect where micro organisms can grow?
1. Tissue tropisms 2. Moisture 3. Temperature 4. pH 5. O2 availability 6. Nature of surface 7. Surface turnover
34
What is tissue tropism
The propensity for a particular organism to grow in a particular habitat
35
Describe the environment on our skin
1. Variable temperatures 2. Dry 3. Subject to abrasion 4. Aerobic environment 5. Nutrient poor 6. Skin surface components
36
Describe the environment in gingival crevices
``` 1. Constant temperature 2, Moist 3. Inaccessible low fluid flow 4. Anaerobic environment 5. Bathes in nutrients ```
37
Where can micro environments form in the skin
1. Toe webs 2. Scalp 3. Palms 4. Axillae
38
Where can micro environment form in the mouth
1. The tooth surface 2. Lingual surface 3. Buccal surface 4. Gingival crevice
39
Where can micro environment form in the nasopharynx
1. Tonsillar crypts | 2. Nasal mucosa
40
Where can micro environments form in the GI tract
1. Stomach 2. Small bowel 3. Large bowel
41
Which site of the body hosts the largest amount of micro organisms
The large intestine (10^9-10^11)
42
Name the main taxon of species found on the skin
Staphylococci (particularly staphylococcus aureus)
43
Name the early colonisers in the oral cavity
Virdans/ oral streptococci
44
Name the most common microorganism found in the nostrils
S aureus
45
List the most common microorganisms found in the pharynx
1. Streptococcus pyogenes 2. Haemophilus influenzae 3. Streptococcus pneumoniae 4. Staphylococcus aureus
46
Describe the distribution of micro organisms in the small intestine
The number of micro organisms increases distal | pH in the GI tract is low which inhibits bacterial growth
47
Describe the micro organisms found in the small intestine
Predominantly facultatively anaerobic bacteria | Very few or no obligate anaerobes
48
Which intestine has more micro organisms small or large
Large (has around 10^9-10^11 organism per gram)
49
How many species of microorganisms have been identified in the large intestine
At last 400
50
How can the resident microbiota of the gut be destroyed or harmed?
By taking antibiotics
51
When does the micro biota of the vagina change?
Post puberty
52
Describe the microbiota of the vagina PRE puberty
Similar to the skin flora and lower GI microbiota
53
Describe the microbiota of the vagina post puberty
A lot of lactobacillus species found
54
Why does the microbiota of the vagina change post puberty
Due to circulating oestrogen producing glycogen
55
What is the role of lactobacillus species in the vagina post puberty
It ferments glycogen which helps to maintain the pH at 3 and prevent the overgrowth of other bacterial species
56
What are the main benefits of the resident human microbiota?
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
What is an opportunistic infection?
An infection caused by an organism that is a member of the normal microbiota or normally inhabits the external environment
58
Give examples of when an opportunistic infection can arise
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
Give examples of opportunistic infections
1. Vaginal thrush 2. Otitis media 3. Conjunctivitis 4. Urinary tract infection 5. Peritonitis 6. Intravascular catheter infection 7. Caries
60
What causes vaginal thrush
Caused by disruption of the normal microbiota of the vagina
61
Give some signs and symptoms of vaginal thrush
Development of vaginal itch with creamy vaginal discharge
62
How is vaginal thrush treated?
With broad spectrum antibiotics for sinusitis
63
What causes otitis media
Translocation of bacteria from one site to another due to surface spread
64
What causes conjunctivitis
Translocation of bacteria from one site to another due to surface spread
65
What does otitis media affect?
The ear drum (ear ache with cough and runny nose)
66
Give some signs and symptoms of conjunctivitis
Red eyes and purulent conjunctival discharge with cough and runny nose
67
What causes urinary tract infection
Translocation of bacteria from one site to another due to surface spread
68
Give some signs and symptoms of urinary tract infection
Urinary frequency and dysuria for 3 days
69
How is a UTI treated
With oral trimethoprim
70
What causes peritonitis?
Translocation of micro organisms from one site to another due to disease progression/ tissue damage Usually due to perforated appendix
71
What causes Intravascular catheter infection ?
Translocation of micro organisms from one site to another due to disease progression/ tissue damage
72
Give examples of micro organisms that can cause caries
1. Streptococcus mutants 2. Lactobacillus species 3. Actinomyces species
73
Give examples of micro organisms that cause periodontal disease
1. Porphyromonas gingivalis 2. Tannerella forsythia 3. Aggregatibacterium 4. Actinomyces 5. Spirochaetes
74
Give examples of micro organisms that cause aspiration pneumonia
Staphylococcus species and some other anaerobes
75
Give examples of micro organisms that cause infective endocarditis
Alpha haemolytic streptococci | Staphylococcus species
76
Give examples of micro organisms that cause abscesses
Streptococcus | Actinocmyces speices
77
Give examples of micro organisms that cause candidiasis
Candida species
78
Give examples of disease that can be caused by resident microbiota if the environment of the host changes
1. Caries 2. Periodontal disease 3. Infective endocarditis 4. Aspiration pneumonia 5. Abscesses 6. Candidasis
79
How can cross infection lead to the development of an opportunistic infection
As the resident microbiota may be harmless in one person but dangerous in another
80
Give examples of opportunistic infections caused by crossing infection
1. Methicillin resistant S aureus (MRSA)
81
What is MRSA
Methicillin resistant S aureus (a superbug)
82
How can we diagnose and identify opportunistic infections
By carrying our non culture based tests
83
Name the 6 classes of antimicrobial resistant phenotypes
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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