Exam 3

Question 1

Define pathogenicity and virulence

Answer 1

Pathogenicity: The ability to cause disease
Virulence: The extent of pathogenicity

Question 2

Virulence factors?

Answer 2

molecules that are expressed or
secreted that enable a pathogen to cause disease
(toxins, enzymes, adhesins, invasins, capsules, iron
acquisition)

Question 3

What are kochs 4 postulates

Answer 3

1. Microbe present only in diseased tissue
2. Isolate microbe from diseased tissue in pure
   culture
3. Pure culture of microbe should cause the
   disease when re-introduced
4. Re-isolate the microbe from the infected
   host.

Question 4

What are the new postulates called and what are they?

Answer 4

Molecular postulates
1. Phenotype or property under investigation
should be associated significantly more often
with pathogenic strains of a species than with
nonpathogenic strains.
2. Inactivation of the gene or genes of interest
should lead to a measurable decrease in
virulence.
3. Re-introduction of the wild-type gene should
restore virulence.

Question 5

what is the equation to determine infectious disease risk?

Answer 5

(dose x virulence)/host status

Question 6

ID50

Answer 6

infectous dose for 50% of the population

Question 7

LD50

Answer 7

Lethal dose for 50% of the population

Question 8

What are the steps of pathogenesis?

Answer 8

1. Colonize (enter and adhere)
2. Evade host defense mechanisms
3. Acquire nutrients and replicate
4. Transmitt to a new host

Question 9

What are the portals of entry?

Answer 9

skin
mucous membranes
parenteral route
Ex:
influenza- inhaled

Question 10

How does the portal of entry modify ID50/LD50?

Answer 10

It changes the dose number depending on the portal of entry

Question 11

What is the advantage of avoiding phagocytic cells

Answer 11

avoid the immune system

Question 12

How do listeria escape from the vacuole

Answer 12

LLO- lyse the vacuolar membrane

Question 13

What dectections methods exsist in cytoplasm of cells

Answer 13

MHC1,

Question 14

HOw does the vacuole modify itself to combat listeria

Answer 14

inhibit maturation
mycrobacterium
inhibit acidification
inhibit ROI/RNS

Question 15

what inhibits ROI/RNS inside the cell

Answer 15

Catalase(h2o2-> water + o2), superoxide dismutase (o2->h2o2)

Question 16

How do microorgranisms survive in the vacuole?

Answer 16

Lysse membrane to escape
Modify by inhibiting maturation
Inhibit aidification

Question 17

antigenic variation

Answer 17

multiple copies of a gene that codes for the same surface protein(different structure).

Question 18

How do they aquire nutrients

Answer 18

Siderophores (Iron Acquistion)
bind to Fe+
steal iron from cells

Question 19

toxins?

Answer 19

hemolysins rupture RBC
staphylococi

Question 20

enzymes?

Answer 20

hyaluronidases- hydrolyze hyaluronic acid
collagenases- hydrolyze collagen
kinases- Digest fibrin clots

Question 21

differences between exotoxins and endotoxins

Answer 21

Endotoxins
G-
Fever inducing
Lipid
Not immunogenic
Heat resistant
Cause inflammation
Large LD50

Question 22

what is pyogeneic

Answer 22

pus forming (made of neutrophils)

Question 23

pyrogeneic

Answer 23

fever inducing

Question 24

Endotoxin-lipid a

Answer 24

stimulate cytokine production by macrophages when release endotoxin in macrophages
pyrogenic response

Question 25

what cytokines are fever inducing?

Answer 25

IL-1,TNF-a (proinflammatory cytokines)

Question 26

endotoxic shock

Answer 26

systemic vasodialation hypotension impaired perfusion of organs

Question 27

disseminated intravascular coagulattion

Question 28

LAL assay

Answer 28

limulus amoebocyte lysate assay amoebocyte lysis produces clot (wbc) endotoxin causes lysis

Question 29

exotoxins

Answer 29

membrane disrupting toxins make protein channels in membrane disrupt phospholipid bilayer pla hydrolyssi of glycerol

Question 30

mechanism superantigens

Answer 30

skip apc process

Question 31

superantigens

Question 32

AB exotoxin

Question 33

protein synthesis disruption

Answer 33

diphtheria toxin

Question 34

how do diphtheria toxins cause protein synthesis?

Question 35

what is EF2

Answer 35

responsible for protein synthesis

Question 36

second messenger disruption

Answer 36

EX:cholera toxin

Question 37

Process of cholera toxin pathway

Question 38

What are G proteins

Question 39

Protease tetanospasmin pathway

Question 40

sope

Answer 40

type 3 secretion system

Question 41

type IV secretion

Answer 41

bacterial ocnjuation transfer of DNA and protein effector molecules Example: pertussis toxin

Question 42

pathogenicity islands(how do we know where there are potential virulence factors)

Answer 42

GC content different from the rest of genome often flanked by mobile elements

Question 43

Examples of organisms that escape from the vacuole?

Answer 43

Listeria

Question 44

How do micobaterium survive in the vacuole?

Answer 44

inhibiting maturation or acidification

Question 45

What are MSCRAMMs

Answer 45

Staphylococcus aureus Microbial surface components recognizing adhesive matrix molecules