wk2- host-microbe interactions

Question 1

what determines the outcome of a symbiotic interaction? 3

Answer 1

host immune response, microbe, environment

Question 2

types of interactions between humans and microorganisms/agents

Answer 2

mutualistic - benefits both
commensal- benefits agent and doesn’t harm human
parasitic- benefits agent, harms human

Question 3

what do endogenous microbiota do for the host 4

Answer 3

-immune priming
-competitive inhibition
-vitamin synthesis
-terminal differentiation of gut mucosa

Question 4

dysbiosis define

Answer 4

disruption to the balance in the endogenous microbiota at a specific anatomical niche

Question 5

imbalances that cause dysbiosis are (3

Answer 5

1. changes in composition of microbial community
2. changes in the functional capacity and metabolic active of the endogenous microbiota
3. a shift in the local distrubtiiton patterns of the microbiota

Question 6

eubiosis define

Answer 6

homeostasis, balance

Question 7

when do opportunisitic infections occur

Answer 7

-when low abundance of commensal members of endogenous microbiota overgrow the usually more abdunent/ protective microbial community members due to lack of competition.

Question 8

steps to transmission (3)

Answer 8

1. source of infectious agents
2. susceptible hosts
3. mode of transmission

Question 9

classification of microorganisms/infectious agents

Answer 9

living and nonliving

living:
bacteria,
fungi,
parasites

nonliving
viruses
pions

Question 10

what is a reservoir

Answer 10

the source/ environement in which the infectious agent persists. these could be humans, animals or non-living environments like water, soil, biofilms

Question 11

bacteria are what

Answer 11

prokaryotes (largest group of infectious agents)

Question 12

fungi are what?

Answer 12

diverse group of eukaryotes

Question 13

transmission occurs between individuals via what methods? 4

Answer 13

direct contact
indirect contact with reservoir
common vehicle
vector

Question 14

direct contact transmission

Answer 14

when susceptible hosts come into contact with the skin or bodily secretions of an infected person

Question 15

indirect contact transmission

Answer 15

when susceptible host touches an inanimate object (fomite) that has been contaminated with an infectious agent

Question 16

vehicle transmission

Answer 16

transmission through a large area by air, water, or food. difference between indirect contact and vehicle is vehicle infects large masses through a single vehicle contaminated

Question 17

vector transmission

Answer 17

vectors are living organisms that transit infectious agents from one host to another. they are usually anthropods. can be either
mechanical vectors - mode of transport between hosts. coacroach or
biological vectors- that participate in the lifecycle of infectious agent. mosquitoes/ticks

Question 18

major portals of exit and entry in the human host ? 2

Answer 18

1. natural openings related to physiological function (nasal, ear, mouth)
2. beaches of barrier integrity (incisions, breaks, bites)

Question 19

2 main barriers for the body and what do they consist of

Answer 19

1. skin- keratin aids waterproofing, keeps inside in/outside out and resistant to bacterial enzymes/toxins. dermis inhibits growth of infectious agents through its sturctures.
2. mucous membranes- mucous covers the tightly packed epithelial cells providing a chemical defense against infectious agents

Question 20

portals of entry can occur through what?

Answer 20

1. respiratory tract
2. gastrointestinal tract
3. skin (injuries)
4. congenital infections
5. urogenital tract

natural openings, skin and congenital infections
but infectious agents must enter host via a specific portal of entry to initiate a new infection as infectious agents have specific tropism

Question 21

portal of exits /shedding can occur through

Answer 21

urine
emsis (vomit)
deification
tidal breathing
blood
coughing
sneezing

Question 22

list features that create a susceptible host 6

Answer 22

1. extremes in age (over 70, under 2years)
2. nutrition (inadequate protein/micronutrients)
3. illness (disrupt physiological function)
4. immunosuppression (immunity suppressed)
5. genetics (physiological function)
6. anatomical defects (physiological function)

Question 23

can commensalism turn into a parasitic interaction?

Answer 23

yes

Question 24

what are biofilms

Answer 24

liquid-solid interface providing a physical protection for the infectious agent against, temp, pH, disinfection, sheering forces, antimicrobial treatment, immune recognition

Question 25

areas in the body usually free from microorganisms

Answer 25

nervous system and circulatory system

Question 26

what are 2 examples of symbiotic endogenous microbiota that reside in the skin/nasa cavity

Answer 26

staphlycoccus and streptococcus and candida

Question 27

what is a symbiotic endogenous microbiota that reside in the respiratory tract

Answer 27

streptococcus

Question 28

in the gastrointestinal tract

Answer 28

lactobacillus

Question 29

genital tract

Answer 29

staphylococcus and lactobacillus and candida