Pathogenicity

Question 1

Pathogenicity

Answer 1

ability to cause disease

Question 2

virulence

Answer 2

the degree of pathogenicity

Question 3

steps microbe must take to cause disease/infection

Answer 3

1. enter organism
2. adhere to tissues
   3.penetrate the tissues
3. damage cells to establish disease
   (evade immune system)

Question 4

Portals of entry

Answer 4

mucous membrane, skin, parental route (cuts),

-don’t necessarily cause disease at this point

Question 5

ID50

Answer 5

infectious dose for 50% of sample population

Question 6

LD50

Answer 6

lethal dose for 50% of population

Question 7

Adherence

Answer 7

adhesins/ligands bind to receptors on host cells

• adhesins on glycocalyx, fimbriae, pili, flagella
• adhesions are typically glycoproteins or lipoproteins
• receptors are usually sugar detectors
• biofilms
• glycocalyx capsules

Question 8

antigenic variateion

Answer 8

pathogens alter their surface antigens

Question 9

glycocalyx

Answer 9

prevents phagocytosis
helps with adherence
can be antigenic

Question 10

invasins

Answer 10

• surface proteins produced by bacteria that rearrange actin filaments of cytoskeleton, causing membrane ruffling in host cells
• some use actin to propel themselves
• some can survive inside phagocytosis or escape before lysosomal fusion or prevent lysosomal fusion

Question 11

virulence factors

Answer 11

molecules produced by bacteria

-coagulases, kinases, hyaluronidase, collagenase, IgA proteases

Question 12

coagulases

Answer 12

coagulate fibrinogen

-clotted blood protects bacteria from phagocytosis

Question 13

kinases

Answer 13

digest fibrin clots to sneak into cells

Question 14

hyaluronidase

Answer 14

digest polysacchrides that hold cell together

Question 15

collagenase

Answer 15

breaks down collagen

Question 16

IgA proteases

Answer 16

destroy IgA antibodies

Question 17

four methods to damage cell

Answer 17

1. use host nutrients
   - 2. direct damage in immediate area
2. toxin production that’re transported to damage far sites
3. hypersensitivity reactions (allergic reactions)

Question 18

using host’s nutrients

Answer 18

siderophores = proteins secreted by pathogens that bind iron better than host cells

Question 19

direct damage

Answer 19

disrupts host cell’s function
produces waste products
multiplies in host cells and cause ruptures

Question 20

toxins

Answer 20

poisonous substances produced by microbes –> fever, heart problems, diarrhea and shock

Question 21

toxigenicity

Answer 21

ability of microbe to produce a toxin

Question 22

intoxication

Answer 22

presence of toxin without microbial growth (e.g. food poisoning)

Question 23

toxemia

Answer 23

presence of toxins in blood

Question 24

exotoxin

Answer 24

proteins produced inside cell and secreted out

• reusable, so a little goes a long way
• may act at far site
• antigenic
• very specific
• destroy host cells or stop host’s functions

Question 25

antitoxin

Answer 25

antibodies against specific exotoxins (usually injected)

Question 26

toxoids

Answer 26

inactivated exotoxins used in vaccines

Question 27

AB exotoxin

Answer 27

contains enzyme component (A) and binding component (B)
-Diptheria toxin and typhoid toxin
B binds to host cell and causes endocytosis
-A exits endosome and does damage while B leaves cell

Question 28

superantigens

Answer 28

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

Question 29

genotoxins

Answer 29

damage DNA, causing mutations, disrupting cell division, leading to cancer

Question 30

Endotoxins

Answer 30

Part of the cell, not a metabolic product
-Lipid A portion of LPS in G- bacteria
-released during bacterial multipulcation or death
-stimulate macrophages to release cytokines in high concentrations
-make hypothalamus produce prostaglandins to increase body temp
-

Question 31

Endotoxins and septic shock

Answer 31

• shock = life threatening decrease in blood pressure
• caused by cytokines
• damages capillaries

Question 32

portals of exit

Answer 32

respiratory tract - coughing and sneezing
gastrointestinal tract - feces and saliva
genitourinary tract - urin and genital secretions
skin
blood - arthropods that bite + needles
saliva