Ch 15 study guide Microbial Mechanisms of Pathogenicity

Question 1

Pathogenicity

Answer 1

the ability to cause disease

Question 2

Virulence

Answer 2

the severity or harmfulness of a disease

Question 3

why is virulence important?

Answer 3

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

Question 4

How are capsules and cell wall components related to pathogenicity? Give specific examples.

Answer 4

Encapsulated bacteria can resist phagocytosis and continue growing.

Question 5

Which of these is NOT how bacteria penetrate host defenses?

Capsule
Cell wall components
Enzymes
Myocotoxins

Answer 5

Myocotoxins

because its a fungi, not a bacteria

Question 6

Describe how hemolysins might contribute to pathogenicity

Answer 6

Hemolysins lyse red blood cells; hemolysis might supply nutrients for bacterial growth

Question 7

Describe how leukocidins might contribute to pathogenicity

Answer 7

Leukocidins destroy neutrophils and macrophages that are active in phagocytosis; this decreases host resistance to infection.

Question 8

Describe how coagulase might contribute to pathogenicity

Answer 8

Coagulase causes fibrinogen in blood to clot;

the clot may protect the bacterium from phagocytosis and other host defenses.

Question 9

Describe how kinases might contribute to pathogenicity

Answer 9

kinases break down fibrin;

kinases can destroy a clot that was made to isolate the bacteria, thus allowing the bacteria to spread.

Question 10

Describe how hyaluronidase might contribute to pathogenicity

Answer 10

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

Question 11

Describe how siderophores might contribute to pathogenicity

Answer 11

Siderophores take iron from host iron-transport proteins, thus allowing bacteria to get iron for growth.

Question 12

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

Answer 12

breaks down collagen which allows for the spread of gas gangrene

Question 13

Describe how IgA proteases might contribute to pathogenicity

Answer 13

destroys IgA antibodies which helps to inhibit immune response

Question 14

Which of the following is not a portal of entry for pathogens?

• mucous membranes of the respiratory tract
• mucous membranes of the gastrointestinal tract
• skin
• blood
• parenteral route

Answer 14

Blood

Question 15

An encapsulated bacterium can be virulent because the capsule

• resists phagocytosis
• is an endotoxin
• destroys host tissues
• kills host cells
• has no effect

Answer 15

resists phagocytosis

Question 16

The earliest smallpox vaccines were infected tissue rubbed into the skin of a healthy person. The recipient of such a vaccine usually developed a mild case of smallpox, recovered, and was immune thereafter. What is the most likely reason this vaccine did not kill more people?

• skin is the wrong portal of entry for smallpox.
• The vaccine consisted of a mild form of the virus.
• Smallpox is normally transmitted by skin-to-skin contact.
• Smallpox is a virus.
• The virus mutated.

Answer 16

skin is the wrong portal of entry for smallpox

Question 17

Tell me what you learned about horseshoe crabs and limulus amebocyte lysate assay? (LAL)

Answer 17

• Horseshoe crabs produce amebocytes that contain Factor C, which coagulates endotoxin found within Gram NEGATIVE bacteria
• Every vaccine was first tested with LAL

Question 18

What are the major routes of microbial entry?

Answer 18

• Mucous membranes
• Skin
• Parenteral route
• Preferred portal of entry

Question 19

What type of action exposes microbes to each specific mucous membrane? (Ex. Food/water for GI tract)

Question 20

Why is the preferred route important?

Answer 20

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

ex, Salmonella typhi causes typhoid fever if swallowed (preferred route). If it is rubbed on skin, no problems occur.

Question 21

What is the definition of ID50?

Answer 21

infectious dose for 50% of a sample population

Measures virulence of a microbe

Question 22

What is the definition of LD50?

Answer 22

lethal dose for 50% of a sample population

Measures potency of a toxin

Question 23

The lower the ID, the more or less virulent?

Answer 23

the lower the ID, the more virulent it is

Question 24

How do capsules help bacteria evade the immune system?

Answer 24

Prevents phagocytic cell from adhering to
the bacterium

Question 25

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

Answer 25

capsule = virulent
no capsule = avirulent

Question 26

Know the examples of enzymes that facilitate microbial colonization of the human body * Both the direct effect and how it assists with survival.

Question 27

Know the three ways by which bacteria can damage host cells

Answer 27

1. Using host’s nutrients
2. Causing direct damage in the immediate vicinity of the invasion
3. Producing toxins, transported by blood and lymph, that damage sites far removed from infection

Question 28

What is hemolysin?

Answer 28

Hemolysin is a membrane-disrupting toxin produced by certain bacteria that lyse red blood cells

kill erythrocytes by forming protein channels

Question 29

What is the major reason why bacteria utilize hemolysin?

Answer 29

Bacteria utilize this toxin to help invade the host more while being able to steal the iron from RBCs

Question 30

Why do bacteria kill red blood cells?

Answer 30

to better outcompete for iron nutrients

Question 31

What is a siderophore?

Answer 31

proteins secreted by pathogens that bind iron more tightly than host cells

Question 32

What is the only example of an endotoxin?

Answer 32

Lipid A is the only endotoxin, found in the Gram - Cell wall

Question 33

Which type of bacteria produces endotoxin?

Answer 33

Gram negative bacteria

Question 34

Which type of bacteria is most likely to secrete exotoxins?

Answer 34

Both Gram-negative and Gram-positive bacteria produce exotoxins

but Gram + is more likely to release exotoxins

Question 35

Know the mechanisms of the three types of exotoxins without knowing specific examples

Answer 35

Type I: Superantigens
Type II: Membrane-Disrupting Toxins
Type III: A-B Toxins

Question 36

A-B Toxins

Answer 36

contain an enzyme component (A part)
and a binding component (B part)

Most exotoxins are A-B
toxins

Question 37

Membrane-Disrupting Toxins

Answer 37

lyse host cells by
disrupting plasma membranes

Question 38

What are Superantigens?
what ailment do they cause?

Answer 38

cause an intense immune response due to
release of cytokines from host cells (T cells)

Cause symptoms of fever, nausea, vomiting, diarrhea,
shock, and death

Question 39

Which 6 toxins were fungal instead of bacterial?

Answer 39

ergot
aflatoxin
mycotoxin
phalloidin
amanitin
lysergic acid diethlylamide(LSD)

Question 40

Know what LAL is and why it is important to the pharmaceutical industry. (hint: horseshoe crabs)

Answer 40

Limulus amebocyte lysate (LAL) assay found in horseshoe crab blood

used to detect the presence and concentration of bacterial endotoxins in drugs and biological products

Question 41

What is the most toxic bacterial exotoxin?

Answer 41

Botulinium toxin (AB toxin) reaslesed from Clostridium botulinium

Question 42

What are the three major routes of microbial entry?

Answer 42

mucus membranes
skin
parenteral route

Question 43

how can microbes gain entry through our mucus membranes?

Answer 43

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

Question 44

how can microbes gain entry through our skin?

Answer 44

hair follicles
sweat glands

Question 45

how can microbes gain entry through our parenteral route?

Answer 45

microbes get put directly into skin (via puncture wounds)

Question 46

What is the number 1 portal of microbial entry?

Answer 46

mucus membranes