Exam 1 Lecture 2

Question 1

Pathogen relationship with host (3 things)

Answer 1

Colonize, multiply, transmission

Question 2

Human relationship with pathogen (2 things)

Answer 2

Infection; Disease

Question 3

Symbiosis

Answer 3

biological association of 2 or more species that may benefit each

Question 4

Commensal

Answer 4

One species benefits, the other remains unharmed

Question 5

Mutualism

Answer 5

both species benefit (vast majority of indigenous microbiota most accurately characterized as mutualistic relationship)

Question 6

Parasitism

Answer 6

parasite benefits at the expense of the host

Question 7

Residents

Answer 7

Bacteria that generally stay for a long time in 1 location/1 body

Question 8

Carrier state

Answer 8

used to describe an individual that would carry a pathogen but not show symptoms

Question 9

Transient

Answer 9

Pathogens that temporarily colonize us

ex: microorganisms that colonize the skin of our hands, which can be removed by handwashing

Question 10

Why are fetuses microbiologically sterile?

Answer 10

There are no viable microbes in or on our body in utero

Question 11

Where do newborn babies acquire their microbiome?

Answer 11

Birth canal, and the skin/respiratory microbiota of hospital personnel and the environment

Question 12

Neonates initially have a ____ group of microbes able to maintain colonization, then as they age, they microbiome is shaped by their environment

Answer 12

Broad

Question 13

What are factors determining the nature of microbiota?

Answer 13

1. Local physio and ecology (microbes present in our GI tract is different than in our nose)
2. Microbial attributes
3. Microbial interactions (competition) - which is crucial because normal microbiota can compete with and exclude pathogens from colonizing

Question 14

True or false: Microorganisms can be possible contaminants, especially problematic for diagnostic purposes

Answer 14

True

Question 15

What is an example of skin microorganisms?

Answer 15

Staphylococcus epidermis, Propionibacterium, Diphtheroids

Question 16

What is an example of conjunctiva microorganisms?

Answer 16

S. epidermidis, non-pathogenic corynebacteria

Question 17

What is an example of mouth microorganisms?

Answer 17

Streptococcus mutans, specifically adhere to teeth

Question 18

How many microorganisms are present per mL of saliva?

Answer 18

10^8 organisms/mL

Question 19

Strict ____ and _____ organisms are associated with the gingival crevice.

Answer 19

anaerobes, microaerophilic

Question 20

What 2 organs are sparsely inhabited by microorganisms?

Answer 20

stomach (pH of 2) and small intestine (site of intense immune surveillance, lots of immune cells here)

Question 21

How much bacteria/mL is present in the colon?

Answer 21

10^10 to 10^11

Question 22

90% of bacteria in the colon are ____, 10% are ____ _____.

Answer 22

anaerobes, facultative anaerobes

Question 23

What is the name of the bacteria that is commonly found in the GI microbiota of breast-fed infants?

Answer 23

Bifidobacterium

Question 24

True or False: A study showed that Bifidobacterium is enriched in exclusively breast fed infants compared to mixed-fed infants.

Answer 24

True

Question 25

True or False: A study showed that Bifidobacterium had no protective advantage against E. coli O157.

Answer 25

False - the mice given probiotic Bifidobacteria were able to fight off O157 infection and survive!

Question 26

True or False: Bifidobacterium makes small molecules that help build epithelial resistance to O157 and thus go against the propagation of E. coli

Answer 26

True

Question 27

Why was the Bifidobacterium [without probiotic effect] significant to our knowledge regarding Bifidobacterium?

Answer 27

The mice without the probiotic effect died off, despite Bifidobacterium being present in their GI tract - thus, the presence of the bacteria itself does not boost survival, but rather there is some activity happening (activity is related to its probiotic effect)

Question 28

Human breastmilk contains ____ which feed bacteria, specifically a bacteria called _______. At the same time, the bacteria helps promote the gut barrier function and specifically protects against the effects of ___.

Answer 28

- human milk oligosaccharides (HMOs) - Bifidobacterium - E coli O157

Question 29

Bifidobacterium expresses ___, which degrades lacto-N-tetraose, an abundant ____...thus, Bifidobacterium feeds on HMOs present in breastmilk.

Answer 29

LnbX | HMO

Question 30

What is the microbiome of the nares (nostrils) similar to and what pathogen do the nares contain?

Answer 30

- Skin | - Contains Staphylococcus aureus

Question 31

What is the microbiome of the nasopharynx similar to and what pathogens does the nasopharynx contain?

Answer 31

- Mouth | - Contains Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae (these all act commensally)

Question 32

What structure is the larynx, middle ear, and sinuses protected by?

Answer 32

Mucociliary escalator

Question 33

True or False: Men are more prone to STIs than women.

Answer 33

False - Women have a shorter urethra than men, which shortens the distance that bacteria must travel to reach the bladder AND the urethra in females is proximal to the vagina and the rectum which is microbiologically rich

Question 34

_____ has an impact on infection.

Answer 34

Anatomy

Question 35

What are some examples of bacteria present in the vagina during the child bearing years?

Answer 35

Lactobacillus, anaerobic GNRs, GPC, Gardnerella, Mycoplasma, Ureaplasma

Question 36

Generally, how are the bacteria present in the vagina before puberty or after menopause different than during child bearing years?

Answer 36

They are mixed and are non-specific from skin, the colon, and perineum

Question 37

List 3 benefits of the normal microbiome

Answer 37

1. Primes our immune system 2. The exclusionary effect (excluding pathogenic organisms from colonizing the host). This is demonstrated by the antibiotic effect. 3. Nutrition: Bacteria can help with digestion (like Bifidobacterium in the GI of infants). There could be malabsorption if too many microorganisms are present. Also, vitamin K is crucial for many proteins in our body that help w/ coagulation.