Micro 3- pathogenesis

Question 1

pathogenicity

Answer 1

the ability to cause disease

Question 2

virulence

Answer 2

the degree of pathogenicity

Question 3

portals of entry

Answer 3

-mucous membranes
-skin
-parenteral route- deposited directly into tissues when barriers are penetrated
(most pathogens have a preferred portal of entry)

Question 4

ID50

Answer 4

infectious dose for 50% of a sample population

-measures virulence of a microbe

Question 5

LD50

Answer 5

lethal dose for 50% of a sample population

-measures potency of a toxin

Question 6

almost all pathogens attach to host tissues in a process called

Answer 6

adherence (adhesion)

Question 7

adhesins (ligands) on the pathogen do what

Answer 7

they bind to receptors on the host cells

• glycocalyx
• fimbriae

Question 8

microbes form

Answer 8

biofilms

which allows for adherence of one microbe to the next

Question 9

list of how pathogens penetrate host defenses

Answer 9

• capsules
• enzymes
• cell wall components
• antigenic variation
• penetration into host cell cytoskeleton

Question 10

how pathogens penetrate host defenses:

capsules

Answer 10

• glycocalyx around the cell wall
• impair phagocytosis
  ex: streptococcus pneumoniae- pnemonia, haemophilus influenzae- pneumonia and meningitis, bacillus anthracis-anthrax, yersinia pestis- plague

Question 11

how pathogens penetrate host defenses:

enzymes -list

Answer 11

• coagulases
• kinases
• hyaluronidase
• collagenase
• IgA proteases

Question 12

enzyme:

coagulases

Answer 12

coagulate fibrinogen

-form “wall” blood clot, fibrinogen precursors for blood clot

Question 13

enzyme:

kinases

Answer 13

digest fibrin clots

(fibrin -> fibrinogen), from host mechanism

Question 14

enzyme:

hyaluronidase

Answer 14

digest polysaccharides that hold cells together

Question 15

enzyme:

collagenase

Answer 15

breaks down collagen

Question 16

enzyme:

IgA proteases

Answer 16

destroy IgA antibodies

Question 17

how pathogens penetrate host defenses:
cell wall components:
M protein

Answer 17

resists phagocytosis

-streptococcus pyogenes

Question 18

how pathogens penetrate host defenses:
cell wall components:
Opa

Answer 18

protein allows attachment to host cells

-neisseria honorrhoeae

Question 19

how pathogens penetrate host defenses:
cell wall components:
Waxy lipid

Answer 19

(mycelia acid) resists digestion

-mycobacterium tuberculosis

Question 20

how pathogens penetrate host defenses:

antigenic variation

Answer 20

pathogens alter their surface antigens (and antibodies are rendered ineffective)

Question 21

how pathogens penetrate host defenses:

penetration into host cell cytoskeleton

Answer 21

using invasins or using actin to move from one cell to the next
e.g. shigella and listeria

Question 22

invasins

Answer 22

surface proteins produced by bacteria that rearrange tin filamentous of the cytoskeleton (membrane ruffling)

Question 23

how can pathogens damage the host?

Answer 23

• using host’s nutrients (siderophores)
• direct damage
• production of toxins

Question 24

damage to host:

using host’s nutrients: siderophores

Answer 24

• iron is required for most pathogenic bacteria

- siderophores are proteins secreted by pathogens that bind iron more tightly than host cells (ex: enterobactin)

Question 25

toxins are

Answer 25

poisonous substances produced by microorganisms | -produce fever, cardiovascular problems, diarrhea, and shock

Question 26

toxigenicity is

Answer 26

the ability of a microorganism to produce a toxin

Question 27

toxemia

Answer 27

presence of toxin in the host's blood

Question 28

intoxications

Answer 28

presence of toxin without microbial growth

Question 29

what are exotoxins?

Answer 29

proteins produced and secreted by bacteria - soluble in bodily fluids, destroy host cells and inhibit metabolic functions - gram positive

Question 30

antitoxins

Answer 30

antibodies against specific exotoxins

Question 31

toxoids

Answer 31

inactivated exotoxins used in vaccines

Question 32

list of types of exotoxins

Answer 32

- AB toxins - membrane disrupting toxins - superantigens

Question 33

AB toxins

Answer 33

contain an enzyme component (A part) and a binding component (B part) example: diphtheria toxin

Question 34

what do membrane disrupting toxins do? 3 types?

Answer 34

they lyse host cells by disrupting plasma membrane 1. leukocidins 2. hemolysins 3. streptolysins

Question 35

leukocidins | membrane- disrupting toxins

Answer 35

kill phagocytic leukocytes

Question 36

hemolysins | membrane-disrupting toxins

Answer 36

kill erythrocytes by forming protein channels

Question 37

streptolysins | membrane- disrupting toxins

Answer 37

hemolysins produced by streptococci

Question 38

superantigens

Answer 38

cause an intense immune response due to the release of cytokines from host cells (T cells) -cause symptoms of fever, nausea, vomiting, diarrhea, shock, and death

Question 39

what are genotoxins?

Answer 39

they are toxins that damage DNA (causing mutations, disrupting cell division, and leading to cancer)

Question 40

what are endotoxins and where do they come from

Answer 40

they are the lipid A portion of lipopolysaccharides (LPS) of gram negative bacteria that are released during bacterial multiplication and when gram negative bacteria die

Question 41

how do endotoxins work?

Answer 41

they stimulate macrophages to release cytokines and cause disseminated intravascular coagulation -> blood clotting in capillaries formed - decreased blood supply, can cause damage to cells and tissues

Question 42

exotoxins vs. endotoxins: | chemistry

Answer 42

exotoxins- proteins (usually with 2 parts- A and B) | endotoxins- lipid protein, lipid A of outer membrane LPS

Question 43

exotoxins vs. endotoxins: | toxicity (ability to cause disease)

Answer 43

exotoxins- high | endotoxins- low

Question 44

exotoxins vs. endotoxins: | bacterial source

Answer 44

exotoxins- mostly gram + | endotoxins- mostly gram -

Question 45

what is lysogenic conversion

Answer 45

changes characteristics of a microbe due to incorporation of a bacteriophage

Question 46

examples of bacteriophage genes:

Answer 46

diptheria toxin, botulinum neurotoxin and capsule produced by streptococcal pneumoniae