Lecture 20

Question 1

microbiome

Answer 1

functional collection of different microbes in a particular environmental system (e.g., the human microbiome).

Question 2

Gastrointestinal microbiota

Answer 2

Responsible for digestion of food, absorption of nutrients, and production of nutrients by the indigenous microbial flora

Question 3

Vaginal Delivery

Answer 3

• Massive fetal exposure to maternal vaginal, fecal (and skin) microbiota
– Bifidobacterium species from the mother’s prenatal feces in the feces of infants born vaginally (but not by C- section)

Question 4

Breastmilk

Answer 4

• Composition: 1. Lactose

2. Fats
3. Over 200 human milk oligosaccharides (HMO)

Question 5

maternal Immune Activation (mIA)

Answer 5

involves elevated levels of inflammatory factors in the blood, placenta, and amniotic fluid during pregnancy that can be caused by viral or bacterial infection

Question 6

Infection:

Answer 6

a situation in which a microorganism is established and growing in a host, whether or not the host is harmed

Question 7

Pathogen

Answer 7

a microbial parasites that cause disease, or tissue damage in a host

Question 8

Pathogenicity

Answer 8

the ability of a parasite to inflict damage on the host

Question 9

bacterial capsule

Answer 9

two important functions:

1. The capsule is sticky and contains specific receptors to facilitate attachment on host tissues.
2. Capsules, such as those found in Streptococcus pneumoniae, protect the bacteria from ingestion by white blood cells.

Question 10

Invasion

Answer 10

the ability of a pathogen to enter into host cells or tissue, spread and cause disease

Question 11

Invasiveness

Answer 11

measure of the ability of a pathogen to grow in host tissue at densities that inhibit host function

Question 12

Bacteremia

Answer 12

the presence of bacteria in the bloodstream

Question 13

Septicemia

Answer 13

bloodborne systemic infection may lead to massive

inflammation, septic shock, and death

Question 14

Infection

Answer 14

any situation in which a microorganism (not a member of the local microbiota) is established and growing in a host

Question 15

Virulence

Answer 15

the measure of pathogenicity, the relative ability of a pathogen to cause disease

Question 16

Nosocomial infections

Answer 16

acquired in the hospital) affect nearly 2 million people each year.

Question 17

Exotoxins

Answer 17

toxic proteins released from pathogens as they grow

Question 18

Enterotoxins

Answer 18

exotoxins whose site of action is the small intestine and generally cause secretion of fluid into the lumen, resulting in vomiting and diarrhea

• Exotoxins fall within three categories defined by mechanism
  1. AB toxins
  2. Cytolytic toxins
  3. Superantigen toxins

Question 19

Cytolytic Exotoxins

Answer 19

soluble proteins secreted by pathogens that damage the host cell membrane causing cell lysis and death

Question 20

Superantigens

Answer 20

proteins that upon exposure to the immune system activate many more T cells than normal, eliciting an unusually strong immune response

Question 21

Endotoxins

Answer 21

the lipopolysaccharide portion of the cell envelope of certain gram-negative
Bacteria, which is a toxin when solubilized generally less toxic than exotoxins