Part 7: Normal Human Microbial Interactions Flashcards Preview

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Flashcards in Part 7: Normal Human Microbial Interactions Deck (65)
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1
Q

Human microbiome

A

The collection of all the microorganisms living in association with the human body

2
Q

Number of human cells in the human body

A

10^13

3
Q

Number of microorganisms in the human body

A

10^14

4
Q

Number of genes in the human genome

A

20,000

5
Q

Number of genes in the microbiome

A

20,000,000

6
Q

When does colonization begin?

A

After birth

7
Q

Where do microbiota live?

A

Every exposed area of the body i.e., skin and mucous membrane

8
Q

What area is free of microbes?

A

Internal tissues i.e., blood, muscles, organs

9
Q

How do microbiota contribute to health?

A

Produce beneficial products

Inhibit the growth of pathogens

10
Q

Benefit of Lactobacillus acidophilus

A

Protects the female reproductive tract

11
Q

Dry skin areas

A

Forearms, hands

12
Q

Dry skin has high numbers of

A

Betaproteobacteria

13
Q

Betaproteobacteria

A

Known from 16 rRNA genes

Rarely cultured

14
Q

Second highest bacteria on dry skin

A

Corynebacteria

15
Q

Corynebacterium diphtheriae

A

Can cause non-healing ulcer of the skin - cutaneous diphtheria

16
Q

Moist skin

A

Armpits, nostrils

17
Q

Moist skin has a high number of

A

Corynebacteria and staphylococci

18
Q

Most frequently isolated bacteria on skin

A

Staphylococcus epidermidis

19
Q

Staphylococcus aureus

A

Pathogen that causes boils, abscesses, wound infections

20
Q

Sebaceous skin has a high number of

A

Propionibacteria

21
Q

Propionibacteria

A

Anaerobic Actinobacteria that produce propionic acid as an end product of fermentation

22
Q

Propionibacterium acnes

A

Lives in hair follicles, and eats sebum - oil secreted by skin
Overgrowth can trigger inflammation - inflammatory acne

23
Q

Antimicrobial enzymes in saliva

A

Lysozyme and lactoperoxidase

24
Q

Lactoperoxidase

A

Catalyzes production of superoxide radicals O2 - oxidative damage to invading microbes

25
Q

What kinds of microbes does the mouth have?

A

Aerobic and anaerobic

26
Q

Neisseria mucosa

A

Aerobic

Lives on mucous membranes like the tongue

27
Q

Streptococcus mutans

A

Aerotolerant anaerobe

28
Q

Streptococcus mutans produces

A

A sticky dextran slime layer that lets it stick to surfaces - forms biofilms in crevices around the motor

29
Q

Streptococcus mutans produces what end-product

A

Lactic acid as an end-product of fermentation

30
Q

Streptococcus mutans degrades

A

Tooth enamel - dental carries

31
Q

Streptococcus mutans leads to

A

Inflammation along the gum line - gingivitis

32
Q

Stomach environment for microbes

A

Low pH and proteolytic enzymes make the stomach inhospitable to most microbes

33
Q

Helicobacter pylori

A

Colonizes surface of membrane, protected from stomach acid by mucous

34
Q

Helicobacter pylori

A

Exotoxin - kills cells in the membrane

Endotoxin - triggers inflammation

35
Q

What is the cause of stomach ulcers?

A

Helicobacter pylori

36
Q

What is helicobacter pylori treated with?

A

Antibiotics - tetracycline

37
Q

Small intestine environment

A

Area of rapidly changing pH

As pH becomes more neutral, bacterial numbers increase

38
Q

Enterococcus

A

Genus of gram positive lactic acid bacteria

Opportunistic pathogen

39
Q

What is the cause of nosocomial infections?

A

Enterococcus

40
Q

Enterococcus mechanism

A

Develop antibiotic resistance readily

Spread resistance genes on to other gram positive bacteria - horizontal gene transfer

41
Q

Large intestine environment

A

pH is neutral, environment anoxic
Enormous number of microbes ~ 10^11 cells/g of feces
Mostly anaerobes and facultative aerobes

42
Q

E. coli

A

Most cultured bacterium from feces - indicator of fecale contamination

43
Q

E. coli strain is

A

Non-pathogenic
May stimulate the immune system
Produce vitamin K

44
Q

What makes up less than 1% of bacteria in the large intestine?

A

E. coli

45
Q

What reveals E. coli is less than 1% of the large intestine?

A

16S rRNA

46
Q

Largest group of bacteria are strict anaerobes are from the genera

A

Bacteroides and Clostridium

47
Q

What roles does Bacteroides and Clostridium play?

A

Role in digestion

48
Q

High number of methanogens play

A

A role in obesity

49
Q

Germ free mice vs. normal mice body fat

A

40% less body fat

50
Q

Innoculated germ free mice with microbes from healthy mouse intestines led to

A

Mice quickly gained weight

51
Q

Microbiomes of normal weight mice vs. genetically obese mice

A

Genetically obese mice had fewer Bacteroidetes, more Firmicutes and way more methanogens

52
Q

What do methanogens use to promote bacterial fermentation?

A

H2

53
Q

What does bacterial fermentation do for the host?

A

Make nutrients available

54
Q

Antibiotic associated colitis

A

Clostridium difficile grow

Inflammation of the colon

55
Q

Treatment of antibiotic associated colitis

A

Further antibiotics
Probiotics
“Transpoosition”

56
Q

Upper respiratory tract environment

A

Home to a variety of bacteria including staphylococci, streptococci, and corynebacteria

57
Q

What pathogen lives in normal microflora?

A

Staphylococcus aureus

58
Q

Lower respiratory tract environment

A

No resident microflora

Mucous, lysozyme, ciliated cells, secretory IgA, phagocytes

59
Q

Upper urinary tract environment

A

Normally free of microoganisms

60
Q

Urethra environment

A

Home to some gram-negative bacteria

61
Q

Normal microbiota in urinary tract

A

Can act as opportunistic pathogens

62
Q

E. coli in the urinary tract causes

A

Urinary tract infections

63
Q

Lactobacillus acidphilus in the vagina produces

A

Lactic acid from glycogen

64
Q

Lactic acid does what in the vagina

A

Lower pH and prevents growth of other microbes

65
Q

If normal microbiota in the vagina is disturbed

A

Yeast can overgrow and cause yeast infections