19. Microbial Interactions/Pathogenicity

Question 1

What is virulence?

Answer 1

The intensity/degree of pathogenicity

Question 2

What is pathogenicity?

Answer 2

The ability to cause disease

Question 3

What is symbiosis?

Answer 3

Close association of 2+ dissimilar organisms

Can be positive or negative

Question 4

3 examples of positive symbiosis?

Answer 4

Mutualism
Cooperation
Commensalism

Question 5

4 examples of negative symbiosis?

Answer 5

Predation
Parasitism
Amensalism
Competition

Question 6

What is amphibiosis

Answer 6

one species can be helpful/harmful/or both simultaneously depending on the circumstances

Question 7

Different between mutualism and cooperation?

Answer 7

Both species benefit, but in mutualism they DEPEND on each other for survival => cooperation they do not

Question 8

What is commensalism

Answer 8

One species benefits

Other unaffected

Question 9

What is amensalism?

Answer 9

One species kills the other

Question 10

What is competition?

Answer 10

One species outcompetes the other for resources

Question 11

Example of mutualism?

Answer 11

Termites and Trichonympha

Tric break down cellulose, turns it to CO2 and H2

Question 12

Microbiologists refer to parasites as what 2 things?

Answer 12

Protozoans (plasmodium)

Worms (tapeworms)

Question 13

What 4 things determine virulence?

Answer 13

Infectivity, invasiveness, adhesiveness, toxigenicity

Question 14

What is a vector?

Answer 14

Living org that transfers an infective agent between hosts

e.g. mosquitoes and malaria

Question 15

What is a vehicle?

Answer 15

Inanimate material that can transmit pathogens

e.g. surgical equipment

Question 16

What is a carrier?

Answer 16

Infected individual who is a potential source of infection for others

Question 17

What are zoonoses?

Answer 17

Infectious diseases that can be transmitted from animals to humans

Question 18

2 examples of zoonoses?

Answer 18

Anthrax (from diseased animal flesh)

Tuberculosis (from contaminated cow’s milk)

Question 19

Example of a skin commensal?

Answer 19

Staphylococcus epidermis

Question 20

Different between resident and transient skin commensals?

Answer 20

Resident = grow on skin

Transient = temporarily on skin

Question 21

6 ways we prevent skin commensals from invading our skin?

Answer 21

Keratinized skin layer

Low water activity (aw)

Skin constantly sloughed

Organic acids (low pH impedes microbial growth)

NaCl (sweat increases solute conc)

Lysozyme (cleaves bacterial NAG-NAM bonds in peptidoglycan)

Question 22

Example of commensalism in human microbiome?

Answer 22

Skin commensals on our skin

Question 23

7 steps a pathogen takes to cause an infectious disease?

Answer 23

1. Maintain a reservoir
2. Be transported to and enter a suitable host through a suitable route
3. Adhere to, colonize, invade host cells
4. Invade host defenses
5. Multiply and complete life cycle
6. Damage host
7. Leave the host

Question 24

4 factors that affect the outcome between host and pathogen?

Answer 24

Inoculum size

Location

Health of host

Virulence of pathogen

Question 25

How to test metabolic interdependence between termites and their associated protist (Trichonympha)?

Answer 25

Expose termites to hyperbaric oxygen

Inside the guy is anaerobic so the protist will die

Termite eventually survives but will ultimately starve since the protists in its gut are dead

Question 26

What is tropism?

Answer 26

Location of the host that will support growth of pathogen

Question 27

Example of an endotoxin? How?

Answer 27

LPS

Initially attached to bacterium, but when it replicates/lyses => LPS released

Question 28

What is an endotoxin?

Answer 28

Cell-associated toxin

Question 29

Example of an exotoxin?

Answer 29

Botulinum toxin

Question 30

3 ways pathogens can evade host defenses?

Answer 30

Change surface antigens

Create a capsule

Reproduce inside host cells to avoid detection