Chapter 14: Microbiome

Question 1

total community of microbes associated with an organism

Answer 1

microbiome/microbiota

Question 2

the microbiome is composed of

Answer 2

bacteria, archaea, fungi, protozoa, viruses

Question 3

organs and tissues that harbor microbiomes

Answer 3

skin, eyes, mouth, nose, oropharynx, stomach, intestines, genitourinary tract

Question 4

organs and tissues that should be kept sterile

Answer 4

bloodstream, respiratory tract (excluding lungs), certain parts of the genitourinary tract

Question 5

number of microorganisms that typically inhabit an environment

Answer 5

bioburden

Question 6

most prominent microbial ecosystems in the body

Answer 6

skin, oral/nasal cavities, genitourinary tract, intestine

Question 7

area of the human body with the highest bioburden

Answer 7

intestine

Question 8

anaerobes outnumber aerobes because they can occur without the presence of _______, making it advantageous in environments where ________ are low or absent

Answer 8

oxygen; oxygen levels

Question 9

the more anaerobic the body site, the more _______ are present

Answer 9

anaerobes

Question 10

even aerobic sites contain __________

Answer 10

anaerobes

Question 11

skin limits microbial growth by

Answer 11

being acidic (pH 4-6), having high salt, low moisture content, and enzymes like lysozyme

Question 12

___________ bacteria are more likely to colonize because they are resistant to salt/dryness

Answer 12

gram-positive

Question 13

imbalance in microbiome composition, leads to skin diseases like rashes, acne, dermatitis, etc.

Answer 13

dysbiosis

Question 14

dysbiosis leads to disease because the imbalanced microbiota is unable to protect itself from ___________ that trigger inflammation, toxins, and carcinogenic metabolites

Answer 14

pathogenic organisms

Question 15

tears contain ____________ such as lysozyme; constant bathing in tears washes away ________

Answer 15

antimicrobial compounds; germs

Question 16

harbors microbes in the eye

Answer 16

tear and oil glands/ducts and eyelash follicles

Question 17

dysbiosis in the eye

Answer 17

infections of the eye surface (conjunctivitis), inflammation against normal microbiota (styes, blepharitis)

Question 18

________ is a strong defense against microbial growth in the mouth, contains antimicrobial compounds like hydrogen peroxide and lysozymes, _______ the mouth, making the environment difficult to adhere to

Answer 18

saliva; washes

Question 19

provide a surface for bacteria to adhere and grow biofilms

Answer 19

teeth

Question 20

aerobic surface in mouth

Answer 20

surface of teeth

Question 21

anaerobic surface in mouth

Answer 21

spaces in between teeth

Question 22

dysbiosis in mouth

Answer 22

can lead to bacteria entering the bloodstream (bacteremia) and lead to toxic shock syndrome and multi-organ failure

Question 23

aerobic surface in oronasopharynx

Answer 23

nasopharynx and oropharynx are oxygen-rich, harbor streptococcus and staphylococcus

Question 24

anaerobic surface in oronasopharynx

Answer 24

small pits along the tonsils contain crypts

Question 25

dysbiosis in oronasopharynx

Answer 25

streptococcus progenies can colonize in the throat and tonsils, establishing a severe infection that can lead to bacteremia and multi-organ failure (aerobic microbiota is colonizing in the wrong spot, causing an imbalance)

Question 26

lungs maintain a low bioburden to the

Answer 26

mucociliary escalator

Question 27

mechanism responsible for clearing the respiratory tract of most foreign debris and microbes

Answer 27

cilia move bacteria in and out of the airways, keeping most microorganisms in the nasopharynx

Question 28

bacteria that enter the trachea are trapped by ______, protects the lungs from this entry

Answer 28

mucus

Question 29

dysbiosis in the lungs

Answer 29

inhalation of too many pathogenic microbes will overwhelm the mucociliary escalator, leading to infection of the lung

Question 30

the stomach inhibits microbial growth due to the

Answer 30

low pH (~2) of the stomach acid

Question 31

bacteria (H. pylori - pathogenic to stomach and first part of intestines) that have pH ______ and can access the ___________ can colonize in the stomach

Answer 31

5-6; mucus lining

Question 32

the intestinal microbiome is fully ________ and has a _______ pH

Answer 32

anaerobic; neutral

Question 33

only anaerobes and facultative anaerobes can survive here; anaerobes are the most _________

Answer 33

intestinal microbiome; abundant

Question 34

the numbers and diversity of the ____________ are greater than any other human microbiome

Answer 34

intestinal microbiome

Question 35

benefits of intestinal microbiome

Answer 35

we absorb 15-20% of our daily calorie intake as microbial byproducts, vitamins and hormones are produced by microbes and absorbed by cells

Question 36

nerves in the GI tract connect the CNS to form the __________ (signaling), bidirectional

Answer 36

microbiome-gut-brain axis

Question 37

neurochemicals from the brain travel to nerves in the gut to alter _________ and __________

Answer 37

gut function and microbiome balance

Question 38

gut microbiome produces __________ that can alter brain function, affecting mood and behavior

Answer 38

neurotransmitters

Question 39

dysbiosis in gut

Answer 39

diseases like depression, parkinsons, and alzheimers

Question 40

microbiomes are constantly _______: normal bacteria compete with pathogens for _________ and ________, and will produce __________ to kill pathogens

Answer 40

changing; binding space and resources; antimicrobial compounds

Question 41

outcomes of severe intestinal dysbiosis

Answer 41

deadly infections from bacteria like C. difficile, inflammatory bowel diseases like Crohn's, bacteremia and organ infection

Question 42

the female genital tract inhibits bacterial growth because

Answer 42

it is slightly acidic (pH 4-5)

Question 43

the bioburden of the genital tract _______ closer to the external environment

Answer 43

increases

Question 44

most dominant bacteria in the vaginal microbiome

Answer 44

acid-tolerant Lactobacillus crispatus or other lactobacilli (prevent invasion of pathogens)

Question 45

dysbiosis of genitourinary microbiome

Answer 45

UTI - bacteria from the urethra can invade the bladder/kidneys yeast infection - fewer lactobacilli in the vagina can lead to colonization of pathogenic bacteria or fungus

Question 46

proposes that dramatic changes in human behavior have influenced the makeup of our microbiota

Answer 46

hygiene hypothesis

Question 47

human behaviors that can dramatically alter our microbiota composition

Answer 47

use of preterm antibiotics -> consequence: reduces vaginal transmission increased bathing/showering, using antimicrobial soaps -> consequence: accelerates change of skin microbiome composition

Question 48

ways to restore a balanced intestinal microbiota

Answer 48

prebiotics, probiotics, fecal microbiota transplant, phage therapies

Question 49

food or supplements that provide plant fibers that can be digested by beneficial bacteria (in natural foods like fruits, veggies, whole grains)

Answer 49

prebiotics

Question 50

food or nutritional supplements that contain live organisms to promote colonization by beneficial bacteria (lactobacillus and bifidobacterium species)

Answer 50

probiotics

Question 51

transfer of the microbiome of a healthy person to a person with severe intestinal disease

Answer 51

fecal microbiota transplant

Question 52

may be a possible alternative to antibiotics in targeting pathogenic bacteria

Answer 52

phage therapies