Bio 220: Virulence

Front 1

What affects virulence?

Back 1

Invasiveness and Toxigencity

Front 2

What factors increase spread (penetration)?

Back 2

enzymatic factors, resists phagocytosis and other factors

Front 3

What are examples of enzymatic factors that increase spread?

Back 3

a. Hyaluronidase
b. Collagenase
c. Streptokinase
d. Lecithinase
e. Hemolysins

Front 4

What is hyaluronidase?

Back 4

an enzyme which increases microbe's invasiveness by breaking down hyaluronic acid (connective tissue matrix)

Front 5

What is collagenase?

Back 5

an enzyme which breaks down collagen

Front 6

What is streptokinase?

Back 6

a fibrinolysin (lyses fibrin) which dissolves clots.

Front 7

What is lecithinase?

Back 7

an enzyme which breaks down lecithin (phospholipid component of cell membranes).

Front 8

What is hemolysins?

Back 8

special lecithinases which can break down erythrocyte plasma membranes. Destruction of RBCs will ultimately favor and promote the growth of bacterial anaerobes

Front 9

What are some examples that resist phagocytosis?

Back 9

1. Enzymatic factors
2. Capsule production
3. Cell Wall Components
4. Flagellation

Front 10

What enzymatic factors resist phagocytosis?

Back 10

leukocidin and coagulase

Front 11

What is leukocidin?

Back 11

Streptococcal (some Staphylococci too) WBC (leukocyte) killing factor WBCs (phagocytes specifically) are literally exploded when they engulf organisms capable of elaborating leukocidin.

Front 12

What is coagulase?

Back 12

enzyme which clots fibrin (reverse activity of streptokinase). Creates walled off areas such as boils (furuncles). Staphylococci can elaborate this enzyme.

Front 13

How does capsule production help resist phagocytosis?

Back 13

well organized and firmly attached glycocalyx forms a capsule. The bacterial organism with its capsule is too large for engulfment by a phagocyte.

Front 14

How do cell wall components that resist phagocytosis?

Back 14

M protein: protein that helps bacteria stick to host epithelial cells. This makes phagocytosis difficult
A protein: see M protein

Front 15

How to flagellation help resist phagocytosis?

Back 15

motile organisms can literally move away from phagocytic cells.

Front 16

What are the other factors that resist phagocytosis?

Back 16

1. Necrotizing factor
2. Hypothermic factor
3. Edema producing factors

Front 17

What is the Necrotizing factor?

Back 17

kills body cells and in doing so, can create anaerobic conditions

Front 18

What is the Hypotherimic factor?

Back 18

decreases body temperatures and decreases immune cell activity

Front 19

What is the Edema producing factor?

Back 19

makes capillaries more permeable. Bacteria can more readily leave these capillaries

Front 20

What factors effect Toxigenicity?

Back 20

exotoxins and endotoxins

Front 21

exotoxins

Back 21

Extremely lethal in some cases. 1 mg. of botulinum toxin can kill approximately 1 million guinea pigs.
1. Produced by mostly Gram positives and some Gram negatives
2. Secreted into fluids by living cells
3. Chemically they are polypeptides
4. Specific tissue affinities and functions
a. cytotoxins
b. neurotoxins
c. enterotoxins
5. Can be denatured by heat or U.V. and inactivated by chemicals. They are not stabile. Therefore, they can be made into a type of vaccine known as toxoids. Toxoids can be injected and will trigger the body into antibody production against the original active exotoxin.
6. Febrile reactions are minimal

Front 22

What are cytotoxins?

Back 22

kill host cells directly or affect functions of cells which are ultimately fatal. Impetigo which is typically caused by Staphylococci in the newborn and Streptococci in toddlers and grade school children is spread by contact and is characterized by pustules that become crusted and rupture. These organisms are producing cytotoxins that can damage RBC’s and injure tissues.

Front 23

What are neurotoxins?

Back 23

interfere with nerve impulse transmission. Clostridium botulinum can secrete a neurotoxin which can cause muscle paralysis.

Front 24

What are enterotoxins?

Back 24

affect cells lining the G. I. tract. Escherichia coli can produce an enterotoxin that is associated with the symptoms of Traveler’s Diarrhea.

Front 25

endotoxins

Back 25

located in cell walls of Gram negative bacteria.
1. Produced by Gram negatives only
2. Released upon lysis of dead cells (walls)
3. Chemically they are lipopolysaccharides (LPS component of Gram negative cell walls)
4. Produce non-specific or generalized reactions. Proteus, for example, can cause urinary tract infections (UTI’s) with the associated symptoms of endotoxins.
a. fever (can be quite pronounced)
b. weakness and aches
c. shock (endotoxic shock from vasodilation and capillary permeability)
5. Endotoxins are heat stabile and cannot be made into toxoids.

Front 26

True/False: Endotoxins are produced by mostly gram positive and some gram negatives.

Back 26

FALSE

Front 27

True/False: Exotoxins are secreted into fluids by livings cells.

Back 27

TRUE

Front 28

True/False: Endotoxins are chemically polypeptides.

Back 28

FALSE

Front 29

True/False: Endotoxins are produced by gram negatives only.

Back 29

TRUE

Front 30

True/False: Exotoxins are released upon lysis of dead cells (walls)

Back 30

FALSE

Front 31

Endotoxins, chemically they are ___.

Back 31

lipopolysaccharides