Chapter 15 Microbial mechanisms of pathogenicity

Question 1

what is pathogenicity?

Answer 1

the ability for a pathogen to cause disease

Question 2

Know why virulence is important.

Answer 2

virulence is how dangerous/deadly a pathogen is
(the degree of pathogenicity)

Question 3

What are the three major routes of microbial entry?

Answer 3

mucus membranes
skin
parenteral route

Question 4

how can microbes gain entry through our mucus membranes?

Answer 4

through the respiratory tract (breathing)
gastrointestinal tract (swallowing)
genitourinary tract (urethra)
conjunctive (eyes)

Question 5

how can microbes gain entry through our skin?

Answer 5

hair follicles
sweat glands

Question 6

how can microbes gain entry through our parenteral route?

Answer 6

microbes get put directly into skin (via puncture wounds)

Question 7

What is the number 1 portal of microbial entry?

Answer 7

mucus membranes

Question 8

How would someone get microbial entry from the respiratory tract?

Answer 8

breathing in through nose or mouth

Question 9

How would someone get microbial entry from the gastrointestinal tract?

Answer 9

food, water, contaminated fingers

Question 10

How would someone get microbial entry from the genitourinary tract?

Answer 10

sexually contracted

Question 11

How would someone get microbial entry from the conjunctiva?

Answer 11

from rubbing eyes

Question 12

Why is the preferred route important?

Answer 12

certain bacteria cannot survive on/in some regions of the body but can flourish in other

(for example, Streptococcus pneumonia cannot cause disease if swallowed but can flourish if inhaled.)

Question 13

What is the definition of ID50?

Answer 13

infectious dose for 50% sample populations (measures virulence of a microbe)

Question 14

What is the definition of LD50?

Answer 14

lethal dose for 50% of sample population (measures potency of a toxin)

Question 15

The lower the ID, the more or less virulent?

Answer 15

the lower the ID, the more virulent it is

Question 16

The lower the LD, the more or less virulent?

Answer 16

the lower the LD, the more virulent it is

Question 17

How do capsules help bacteria evade the immune system?

Answer 17

prevents phagocytic cell from adhering to the bacterium

Question 18

If a bacteria has a capsule, is it virulent or avirulent? Vice versa?

Answer 18

• capsule = virulent
• no capsule = avirulent

Question 19

what is the effect of coagulases and how it assists with survival of pathogens within the human body?

Answer 19

clot the fibrinogen in blood which protects against phagocytosis and other defenses

Question 20

what is the effect of kinases and how it assists with survival of pathogens within the human body?

Answer 20

break down blood clots from by body in order to release trapped bacteria to wherever it needs to go

Question 21

what is the effect of hyaluronidase and how it assists with survival of pathogens within the human body?

Answer 21

hydrolyses hyaluronic acid which holds together connective tissue, allowing for the organism to spread and also causes tissue blackening (gas gangrene)

Question 22

what is the effect of collagenase and how it assists with survival of pathogens within the human body?

Answer 22

breaks down collagen which allows for the spread of gas gangrene

Question 23

what is the effect of IgA proteases and how it assists with survival of pathogens within the human body?

Answer 23

destroys IgA antibodies which helps to inhibit immune response

Question 24

3 ways by which bacteria can damage host cells?

Answer 24

1. using host nutrients (like iron)
2. causing direct damage (lysing/destruction of host cells)
3. produce toxins (inhibit host cell protein synthesis)

Question 25

what is hemolysin?

Answer 25

kill erythrocytes by forming protein channels

Question 26

Why do bacteria kill red blood cells?

Answer 26

To gain iron within and around RBCs

Question 27

What is a siderophore?

Answer 27

proteins secreted by pathogens which bind to iron more strongly than host cells

Question 28

What is the only example of an endotoxin? Which type of bacteria produces endotoxin?

Answer 28

Lipid A only within gram negative

Question 29

Which type of bacteria is most likely to secrete exotoxins?

Answer 29

both gram negative and gram positive can excrete exotoxins but gram positive is most likely to

Question 30

what are the names of all three exotoxins?

Answer 30

superantigens membrane-disrupting toxins A-B toxins

Question 31

what is a superantigen

Answer 31

exotoxin causing intense immune response due to cytokines from host cells

Question 32

what is a membrane-disrupting toxin?

Answer 32

exotoxin causing lysis of host cells by disrupting plasma membrnaes

Question 33

what is A-B toxin?

Answer 33

exotoxin that contains an enzyme/binding component causing inhibition of protein synthesis

Question 34

Which 6 toxins were fungal instead of bacterial?

Answer 34

ergot aflatoxin mycotoxin phalloidin amanitin lysergic acid diethlylamide (LSD)

Question 35

what are the Salem witch trials thought to be caused by?

Answer 35

ergot released in working fields

Question 36

Know what LAL is and why it is important to the pharmaceutical industry

Answer 36

LAL is found in horseshoe crab blood. Its importance is that it is a specific protein that can coagulate around endotoxins allowing for it to test pharmaceutical drugs, hospital equipment that enters our body, and surgical tools for endotoxins