19. Microbial Interactions/Pathogenicity Flashcards Preview

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Flashcards in 19. Microbial Interactions/Pathogenicity Deck (30)
1

What is virulence?

The intensity/degree of pathogenicity

2

What is pathogenicity?

The ability to cause disease

3

What is symbiosis?

Close association of 2+ dissimilar organisms

Can be positive or negative

4

3 examples of positive symbiosis?

Mutualism
Cooperation
Commensalism

5

4 examples of negative symbiosis?

Predation
Parasitism
Amensalism
Competition

6

What is amphibiosis

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

7

Different between mutualism and cooperation?

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

8

What is commensalism

One species benefits
Other unaffected

9

What is amensalism?

One species kills the other

10

What is competition?

One species outcompetes the other for resources

11

Example of mutualism?

Termites and Trichonympha

Tric break down cellulose, turns it to CO2 and H2

12

Microbiologists refer to parasites as what 2 things?

Protozoans (plasmodium)
Worms (tapeworms)

13

What 4 things determine virulence?

Infectivity, invasiveness, adhesiveness, toxigenicity

14

What is a vector?

Living org that transfers an infective agent between hosts

e.g. mosquitoes and malaria

15

What is a vehicle?

Inanimate material that can transmit pathogens

e.g. surgical equipment

16

What is a carrier?

Infected individual who is a potential source of infection for others

17

What are zoonoses?

Infectious diseases that can be transmitted from animals to humans

18

2 examples of zoonoses?

Anthrax (from diseased animal flesh)

Tuberculosis (from contaminated cow's milk)

19

Example of a skin commensal?

Staphylococcus epidermis

20

Different between resident and transient skin commensals?

Resident = grow on skin

Transient = temporarily on skin

21

6 ways we prevent skin commensals from invading our skin?

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)

22

Example of commensalism in human microbiome?

Skin commensals on our skin

23

7 steps a pathogen takes to cause an infectious disease?

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

24

4 factors that affect the outcome between host and pathogen?

Inoculum size

Location

Health of host

Virulence of pathogen

25

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

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

26

What is tropism?

Location of the host that will support growth of pathogen

27

Example of an endotoxin? How?

LPS

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

28

What is an endotoxin?

Cell-associated toxin

29

Example of an exotoxin?

Botulinum toxin

30

3 ways pathogens can evade host defenses?

Change surface antigens

Create a capsule

Reproduce inside host cells to avoid detection