10. normal microbiota

Question 1

the population of microorganisms that inhabit the skin, intestinal tract and mucus membrane of a healthy normal person

Answer 1

normal microbiota

Question 2

the ___ rRNA gene sequencing and an advanced technology associated with next-generation nucleotide sequencing and metagenomics are used to study the microbiota

Answer 2

16S

Question 3

this is the collective genomes of the normal microbiota in the body

Answer 3

microbiome

Question 4

__________ was launched in 2007 by the National Institutes of Health (NIH) in USA

Answer 4

human microbiome project (HMP)

Question 5

what were the 2 main goals of the human microbiome project?

Answer 5

to understand….
1. the range of the genetic and physiologic diversity of the human microbiome
2. the factors that influence the distribution and evolution of the microbiota

Question 6

what was the main outcome of the HMP?

Answer 6

main outcome: there is no single healthy microbiome. rather, each person harbours a unique collection of microorganisms that assemble from a lifetime of interaction with their environment, diet, medications and many other factors

Question 7

T/F: a healthy fetus is sterile

Answer 7

true

Question 8

infants delivered ____ harbour microbiota that are most similar in composition to the vaginal microbiota of the mothers

Answer 8

vaginally

Question 9

infants delivered _____ harbour microbiota from the skin of the mothers and from the skin of the caretakers (nurses, doctors, midwives, parents, etc)

Answer 9

C-sectiom

Question 10

what bacteria colonize the infant intestinal tract early on?

Answer 10

E. coli and streptococci

Question 11

E.coli and streptococci that colonize the infant intestinal tract establish the growth of anaerobes such as:

Answer 11

bifidobacteria and bacteriodetes.

Question 12

this bacteria is dominant in a breastfed infants gut. it is able to transport and ferment breast milk sugars which provides calories for the growing baby. It is able to synthesize all amino acids and other required growth factors. it is found that a robust immune response to vaccination is linked to the presence of ___________ in an infants gut

Answer 12

bifidobacteria

Question 13

T/F: bifidobacteria raises the gut pH

Answer 13

false - it lowers the gut pH which helps limit the growth of certain pathogens

Question 14

T/F: bottle fed babies have a much smaller proportion of intestinal Bifidobacteria

Answer 14

true

Question 15

T/F: switching to cows milk or solid food results in the loss of Bifidobacteria predominance in the infants gut

Answer 15

true

Question 16

the initial microbiome changes with the host age, gender and the associated physiological and anatomical differences until a stable resident microbiota is formed. Around what age is the normal/resident microbiota formed?

Answer 16

around 3-4 years old

Question 17

the normal microbiota for each individual is heavily influenced by what factors?

Answer 17

• genetics
• developmental changes (e.g. puberty, menopause)
• anatomical site
• diet
• personal hygiene
• life events (antimicrobial use, travel, occupation, sexual partners, etc)

Question 18

what are the five major phyla related to the human microbiota?

Answer 18

1. actinobacteria
2. bacteroidetes
3. firmicutes
4. fusobacteria
5. proteobacteria

Question 19

this group of microbiota consists of relatively fixed types of microorganisms regularly found in a given area at a given age; if disturbed, they reestablish themselves

Answer 19

the resident microbiota

Question 20

this group of microbiota consists of non-pathogenic or potentially pathogenic microorganisms that inhabit the skin or mucous membranes for hours, days, or weeks.
- derived from the environment
- does not establish itself permanently
- are generally of little significance as long as the normal resident microbiota remain intact

Answer 20

the transient microbiota

Question 21

T/F: if the resident microbiota is disturbed, transient microqogransims may colonize, proliferate and produce disease

Answer 21

true

Question 22

what are the 3 types of normal microbiota?

Answer 22

1. commensal microbiota
2. mutualistic microbiota
3. opportunistic microbiota

Question 23

this type of normal microbiota, under normal conditions, lives as commensal but they cause disease if the opportunity arises. e.g. E.coli normal flora of GI tract causes UTI when changing it habitat

Answer 23

opportunistic microbiota

Question 24

this type of normal microbiota gets benefits from the host and at the same time gives benefits to the host. e.g. microbiota in the intestinal tract -> synthesize vitamins and bioactive compounds

Answer 24

mutualistic microbiota

Question 25

this type of normal microbiota gets benefits from the human host and seems that is has no direct benefits for the host. e.g. the microbiota that is present on some body surface

Answer 25

commensal microbiota

Question 26

what are some beneficial roles of normal microbiota?

Answer 26

• prevent attachment and penetration of pathogens
• compete with pathogens for habitat and nutrition
• produce antimicrobial secretions
• immunity
• produces enzymes and vitamins
• helps in metabolism
• oxidation and hydrolysis of steroids

Question 27

this has a slightly acidic pH, a high concentration of sodium chloride, a lack of moisture in many areas, an oily lubricant sebum and antimicrobial peptides.

Answer 27

skin surface or epidermis

Question 28

what are the three environmental niches on the skin surface?

Answer 28

moist sites (typically skin creases)
dry sites (flat surfaces)
sebaceous/oily sites

Question 29

the predominant resident microbiota of the skin are ______ and ______

Answer 29

aerobics and anaerobic

Question 30

what is the causative agent of acne?

Answer 30

diptheroid bacilli Cutibacterium acnes

Question 31

what are two examples of non-hemolytic aerobic and anaerobic staphylococci found in the microbiota of the skin

Answer 31

staphyloccous epidermidis
staphylococcus aureus

Question 32

_____ and _____ are often present in skin folds

Answer 32

fungi and yeasts

Question 33

what are some examples of the predominant resident microbiota of the skin

Answer 33

• cultibacterium acnes
• staphylococcus epidermis
• enterococcus species
  etc.

Question 34

what are some facts that may be important for eliminating transient bacteria from the skin?

Answer 34

• the low (acidic) pH
• the fatty acids in sebaceous secretions
• lysozyme (in tears, salvia and milk)

Question 35

true/false: profuse sweating or washing and bathing can eliminate the normal resident microbiota

Answer 35

false

Question 36

true/false: the number of superficial microbiota may be diminished by vigorous daily washing with soap containing hexachlorophene or other disinfectants

Answer 36

true

Question 37

anaerobes and aerobic microbiota often join to form ________ infections (gangrene, necrotizing factors, and cellulitis) of skin and soft tissues

Answer 37

synergistic

Question 38

name some species found the mouth

Answer 38

• Viridians streptococci
• Lactobacilli
• Staphylococcus
• Streptococcus sanguis (dental plaque)
• Streptococcus mutans (dental plaque)
• yeasts (candida)

Question 39

what parts of the upper respiratory tract are usually sterile?

Answer 39

the small bronchi and alveoli

Question 40

the stomachs acidity keeps the number of flora at a minimum (10^2-10^3/mL of contents); only “this type” of bacteria persists in this environment which cause stomach ulcers

Answer 40

Helicobacter pylori

Question 41

in the intestine, there is a pH change compared to the stomach; does the resident flora gradually increase or decrease in the intestine

Answer 41

increase

Question 42

where in the intestinal tract has the least and the most bacteria?

Answer 42

least - stomach
most - cecum and transverse colon

Question 43

in the adult colon, 96-99% of the resident bacterial flora consists of ____________ (aerobes or anaerobes)

Answer 43

anaerobes

Question 44

this is an archae and produces methane. it is found in the colon microbiota in a low abundance and has a role in stabilizing gut microbial communities

Answer 44

Methanobrevibacter smithiiare

Question 45

______ and _____ are found in the colon flora, whose functions are less well understood than archaeologists like Methanobrevibacter smithiiare

Answer 45

protozoans and fungi

Question 46

what class of viruses are most likely found in the colon

Answer 46

phages

Question 47

long term treatment with antibiotics could cause diarrhea, and in severe cases it could cause ____________

Answer 47

Pseudomembranous colitis

Question 48

the feeding of large quantities of ______, which is also found in yoghurt, may help the reestablishment of the microflora in the gut

Answer 48

Lactobacillus acidophilus

Question 49

soon after birth, aerobic _________ appear in the vagina and persist as long as the pH remains acidic (usually several weeks)

Answer 49

Lactobacilli

Question 50

when the pH in the vagina becomes neutral (remaining so until puberty) after birth, a mixed biota of _____ and _____ is present

Answer 50

cocci and bacilli

Question 51

at puberty, aerobic and anaerobic _________ reappear in large numbers and contribute to the maintenance of acid pH to prevent the vagina from harmful microbes

Answer 51

Lactobacilli

Question 52

if Lactobacilli are suppressed in the vagina by some antibiotics, then yeasts or various bacteria can cause irritation and inflammation (vaginitis) or ________________

Answer 52

bacterial vaginosis