Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y2 MECHANISMS OF DISEASE > Normal Microbiota > Flashcards

Normal Microbiota Flashcards

1
Q

Which areas of the body tend to have a higher organism density?

A

moist or protected areas, such as the armpits or groin area dry, exposed areas of skin harbour fewer organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where in the body has the highest organism density?

A

the oral cavities and colon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is meant by normal flora/microbiota?

A

organisms found in a given location in a state of health

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is meant by colonisation?

A

the establishment of microorganisms at a site in the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is meant by microbiota?

A

all the organisms within a given community

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is meant by the microbiome?

A

all the genes present within the microbiota

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is meant by symbiosis?

A

when two or more organisms co-exist in close physical association

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is meant by mutualism in symbiosis?

A

When both organisms involved benefit from symbiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is meant by neutralism in symbiosis?

A

When neither of the organisms involved derive benefit or harm from symbiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is meant by commensalism in symbiosis?

A

When one organism benefits and the other derives neither benefit nor harm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is meant by parasitism in symbiosis?

A

When one organism (parasite) benefits at the expense of the other (host)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the difference between sterile and non-sterile sites in the body?

A

non-sterile sites have normal flora sterile sites have no normal flora

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is significant about non-sterile sites?

A

They are exposed to the environment, either directly or indirectly There is no mechanism in place to maintain sterility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 5 main non-sterile sites?

A
  1. conjunctiva 2. nasopharynx 3. GI tract 4. vagina 5. skin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When does the acquisition of normal flora begin?

A

at birth until birth, sterility is maintained throughout

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How can blood cultures/CSF/ pleural fluid samples be contaminated?

A

they are obtained by passing a needle through the skin to the relevant sterile site there is potential for contamination with skin organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are sputum samples obtained? What is the problem with sterility?

A

obtained by expectoration of lower airways secretions (sterile site) through the upper airways (non-sterile site) there is a risk of contamination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How are urine samples obtained? What is the problem with sterility?

A

obtained by passing urine from the bladder/upper urinary tract (sterile site) via the terminal urethra (non-sterile site) Risk of contamination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How is the risk of contamination minimised when collecting a urine sample?

A

by collecting an MSU sample (mid-stream urine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the 3 ways in which sterility is maintained at sterile sites?

A
  1. sterility maintained by surface cleaning 2. sterility maintained by barriers that allow unidirectional flow 3. sterility maintained by physical separation from non-sterile sites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are examples of areas where sterility is maintained by surface cleaning?

A

areas that are open to the environment such as the lower respiratory tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are examples of areas where sterility is maintained by barriers?

A

areas that are adjacent to non-sterile sites e.g. the urinary tract is protected by the urethra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are examples of areas where sterility is maintained by physical separation?

A

any closed cavities e.g. spinal cord and meninges, pleural cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is meant by tissue tropism?

A

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

25
Q

What are the 5 main physical variables that influence which organisms colonise which areas?

A
  1. moisture 2. temperature 3. pH 4. O2 availability 5. nature of the surface
26
Q

Where are most bacteria found on the skin?

A

within the sweat glands

27
Q

What is the temperature, O2 levels, nutrient levels and characteristics of the skin?

A
  1. variable temperature 2. dry and subject to abrasion 3. aerobic environment 4. nutrient-poor
28
Q

What is the temperature, O2 levels, nutrient levels and characteristics of the gingival crevice?

A
  1. constant temperature 2. moist with few physical challenges 3. anaerobic environment 4. nutrient-rich
29
Q

What are the 3 most common skin flora?

A
  1. coagulase-negative staphylococci 2. staphylococcus aureus 3. propionibacterium species
30
Q

What is the problem when analysing bacteria on the skin?

A

the bacteria on the skin near any body orifice may be similar to those within the orifice

31
Q

What are the typical flora found within the mouth?

A

viridans/oral streptococci anaerobes

32
Q

What are the typical flora found within the nostrils?

A
  1. any of the skin flora 2. staphylococcus aureus - the nose is the main carrier site
33
Q

What is the problem if the respiratory tract epithelium becomes damaged?

A

any of the microorganisms present in the pharynx can cause infection in the lower respiratory tract

34
Q

What are examples of flora that are present within the pharynx?

A
  1. streptococcus pyogenes 2. haemophilus influenzae 3. streptococcus pneumoniae 4. s. aureus 5. neisseria meningitidis
35
Q

What is the normal flora in the vagina pre-puberty?

A
  1. any of the skin flora 2. lower GI flora - mainly E. coli
36
Q

What is the normal flora in the vagina post-puberty? Why does this change?

A

Glycogen is produced due to circulating oestrogens 1. lactobacillus acidophilus ferment glycogen 2. skin flora 3. a few C. albicans

37
Q

What is significant about lactobacillus acidophilus fermenting glycogen?

A

they maintain the pH of the vagina at 3 This prevents the overgrowth of other species An overgrowth of C. albicans causes thrush

38
Q

What are the typical flora found within the stomach and small intestine?

A

predominantly aerobic bacteria: 1. acid-tolerant lactobacilli 2. helicobacter pylori the low gastric pH inhibits bacterial growth

39
Q

How can H. pylori survive in the stomach despite the acidic pH?

A

it produces urease that converts urea into ammonia and carbon dioxide

40
Q

What are the normal flora found within the large intestine?

A

99% anaerobes such as: 1. bacteroides 2. clostridium 3. bifidobacteria The aerobic bacteria are enteric Gram-negative bacilli

41
Q

What mechanism prevents the overgrowth of pathogens within the large intestine?

A

colonisation resistance by the normal gut microflora

42
Q

How can the normal flora provide a health benefit through metabolism?

A
  1. vitamins K and B12 are secreted by enteric bacteria 2. unused energy substrates are fermented to produce short-chain fatty acids
43
Q

What is the benefit of vitamin K production?

A

E. coli in the colon produce vitamin K It is essential for blood clotting and bone metabolism

44
Q

What are the benefits of butyrate (SCFA)?

A

it helps to prevent bowel cancer and modulates immune responses

45
Q

What are the benefits of propionate (SCFA)?

A

it promotes saiety it prevents lipid lipidogenesis it lowers cholesterol it provides anti-carcinogenic activities

46
Q

How can normal flora provide colonisation resistance?

A

Through environmental manipulation e.g. lowering the pH Through production of antibacterial agents e.g. bacteriocins

47
Q

In what other way can normal flora provide health benefits?

A

through induction of cross-reactive antibodies

48
Q

In general, in what 4 ways can SCFAs provide health benefits to the body?

A
  1. help to inhibit enteropathogens 2. provide energy to epithelial cells/colonocytes 3. promote mucin production 4. affects gut hormone production and modulates appetite
49
Q

How can antibiotics negatively impact normal flora?

A

antibiotics kill off pathogenic organisms and normal flora this reduces the diversity which is key to the health benefits of the normal flora

50
Q

What is the main risk factor for clostridium difficile infection?

A

antibiotic treatment

51
Q

What is the background behind C. difficile infection?

A

perturbation of normal colonic microflora allows C. difficile overgrowth this leads to toxin production

52
Q

In what 3 ways may there be a pathology of the normal flora?

A
  1. overgrowth 2. translocation 3. cross-infection
53
Q

What is meant by overgrowth of normal flora?

A

excessive growth at the normal site

54
Q

What is meant by translocation of normal flora?

A

presence of the normal flora at the wrong site this may be as they have been spread from one site to another

55
Q

What is an example of a condition caused by overgrowth of normal flora? What may have caused this?

A

thrush treatment with a broad spectrum antibiotic can lead to inhibition of colonisation resistance

56
Q

What is an example of a condition caused by translocation where normal flora have been moved from one surface to another?

A

conjunctivitis red eyes with purulent conjuctivital discharge following URTI with cough and runny nose

57
Q

What are typical clinical conditions caused by normal flora?

A
58
Q

Why is it often difficult to determine the clinical significance of the presence of normal flora in a sample?

A

The opportunity for sample contamination is high

Organisms are often present in a sample benignly and are not the cause of symptoms

Y2 MECHANISMS OF DISEASE (36 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions