Part 7: Normal Human Microbial Interactions

Question 1

Human microbiome

Answer 1

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

Question 2

Number of human cells in the human body

Answer 2

10^13

Question 3

Number of microorganisms in the human body

Answer 3

10^14

Question 4

Number of genes in the human genome

Answer 4

20,000

Question 5

Number of genes in the microbiome

Answer 5

20,000,000

Question 6

When does colonization begin?

Answer 6

After birth

Question 7

Where do microbiota live?

Answer 7

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

Question 8

What area is free of microbes?

Answer 8

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

Question 9

How do microbiota contribute to health?

Answer 9

Produce beneficial products

Inhibit the growth of pathogens

Question 10

Benefit of Lactobacillus acidophilus

Answer 10

Protects the female reproductive tract

Question 11

Dry skin areas

Answer 11

Forearms, hands

Question 12

Dry skin has high numbers of

Answer 12

Betaproteobacteria

Question 13

Betaproteobacteria

Answer 13

Known from 16 rRNA genes

Rarely cultured

Question 14

Second highest bacteria on dry skin

Answer 14

Corynebacteria

Question 15

Corynebacterium diphtheriae

Answer 15

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

Question 16

Moist skin

Answer 16

Armpits, nostrils

Question 17

Moist skin has a high number of

Answer 17

Corynebacteria and staphylococci

Question 18

Most frequently isolated bacteria on skin

Answer 18

Staphylococcus epidermidis

Question 19

Staphylococcus aureus

Answer 19

Pathogen that causes boils, abscesses, wound infections

Question 20

Sebaceous skin has a high number of

Answer 20

Propionibacteria

Question 21

Propionibacteria

Answer 21

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

Question 22

Propionibacterium acnes

Answer 22

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

Question 23

Antimicrobial enzymes in saliva

Answer 23

Lysozyme and lactoperoxidase

Question 24

Lactoperoxidase

Answer 24

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

Question 25

What kinds of microbes does the mouth have?

Answer 25

Aerobic and anaerobic

Question 26

Neisseria mucosa

Answer 26

Aerobic | Lives on mucous membranes like the tongue

Question 27

Streptococcus mutans

Answer 27

Aerotolerant anaerobe

Question 28

Streptococcus mutans produces

Answer 28

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

Question 29

Streptococcus mutans produces what end-product

Answer 29

Lactic acid as an end-product of fermentation

Question 30

Streptococcus mutans degrades

Answer 30

Tooth enamel - dental carries

Question 31

Streptococcus mutans leads to

Answer 31

Inflammation along the gum line - gingivitis

Question 32

Stomach environment for microbes

Answer 32

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

Question 33

Helicobacter pylori

Answer 33

Colonizes surface of membrane, protected from stomach acid by mucous

Question 34

Helicobacter pylori

Answer 34

Exotoxin - kills cells in the membrane | Endotoxin - triggers inflammation

Question 35

What is the cause of stomach ulcers?

Answer 35

Helicobacter pylori

Question 36

What is helicobacter pylori treated with?

Answer 36

Antibiotics - tetracycline

Question 37

Small intestine environment

Answer 37

Area of rapidly changing pH | As pH becomes more neutral, bacterial numbers increase

Question 38

Enterococcus

Answer 38

Genus of gram positive lactic acid bacteria | Opportunistic pathogen

Question 39

What is the cause of nosocomial infections?

Answer 39

Enterococcus

Question 40

Enterococcus mechanism

Answer 40

Develop antibiotic resistance readily | Spread resistance genes on to other gram positive bacteria - horizontal gene transfer

Question 41

Large intestine environment

Answer 41

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

Question 42

E. coli

Answer 42

Most cultured bacterium from feces - indicator of fecale contamination

Question 43

E. coli strain is

Answer 43

Non-pathogenic May stimulate the immune system Produce vitamin K

Question 44

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

Answer 44

E. coli

Question 45

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

Answer 45

16S rRNA

Question 46

Largest group of bacteria are strict anaerobes are from the genera

Answer 46

Bacteroides and Clostridium

Question 47

What roles does Bacteroides and Clostridium play?

Answer 47

Role in digestion

Question 48

High number of methanogens play

Answer 48

A role in obesity

Question 49

Germ free mice vs. normal mice body fat

Answer 49

40% less body fat

Question 50

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

Answer 50

Mice quickly gained weight

Question 51

Microbiomes of normal weight mice vs. genetically obese mice

Answer 51

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

Question 52

What do methanogens use to promote bacterial fermentation?

Answer 52

H2

Question 53

What does bacterial fermentation do for the host?

Answer 53

Make nutrients available

Question 54

Antibiotic associated colitis

Answer 54

Clostridium difficile grow | Inflammation of the colon

Question 55

Treatment of antibiotic associated colitis

Answer 55

Further antibiotics Probiotics "Transpoosition"

Question 56

Upper respiratory tract environment

Answer 56

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

Question 57

What pathogen lives in normal microflora?

Answer 57

Staphylococcus aureus

Question 58

Lower respiratory tract environment

Answer 58

No resident microflora | Mucous, lysozyme, ciliated cells, secretory IgA, phagocytes

Question 59

Upper urinary tract environment

Answer 59

Normally free of microoganisms

Question 60

Urethra environment

Answer 60

Home to some gram-negative bacteria

Question 61

Normal microbiota in urinary tract

Answer 61

Can act as opportunistic pathogens

Question 62

E. coli in the urinary tract causes

Answer 62

Urinary tract infections

Question 63

Lactobacillus acidphilus in the vagina produces

Answer 63

Lactic acid from glycogen

Question 64

Lactic acid does what in the vagina

Answer 64

Lower pH and prevents growth of other microbes

Question 65

If normal microbiota in the vagina is disturbed

Answer 65

Yeast can overgrow and cause yeast infections