15- Chapter 25

Question 1

What is pathogenesis?

Answer 1

How pathogens can cause disease

To understand synthesize and articulate concepts related to pathogenesis of microorganisms

Question 2

What are pathogens, pathogenicity, virulence, opportunistic pathogen, infection, and disease?

Answer 2

Pathogens- microbial parasites
Pathogenicity- ability of parasite to inflict damage on host
Virulence- measure of pathogenicity (highly virulent means easily killed)
Opportunistic pathogen- causes disease only in absence of normal host resistance
Infection- microorganism is established and growing in a host, whether or not host is harmed
Disease- damage or injury to host that impairs host function

Question 3

What is toxicity, invasiveness, and attenuation?

Answer 3

Toxicity- organism produces a toxin that inhibits host cell function or kills host cells
Invasiveness- ability of a pathogen to grow in host tissue at densities that inhibit host function
(Can cause damage without producing toxin)
Attenuation- decrease or loss of virulence

Question 4

What are the two ways bacterial adherence is facilitated?

Answer 4

Extracellular macromolecules can be covalently attached to the bacterial cell surface

Fimbriae and pili attached to surface of glycoproteins

Pathogen must usually gain access to host tissues and multiply before damage can be done

Question 5

What is invasion in pathogens?

What increases Invasiveness?

Answer 5

Ability of pathogen to spread and cause diseases
Pathogens can produce virulence factors that increase invasiveness:
Enzymes do by breaking down host tissue to provide access to nutrients and protect pathogen by interfering with normal goat defence mechanism

Question 6

What is bacteremia and septicemia?

Answer 6

Bacteremia- the presence of bacteria in bloodstream

Septicemia- bloodborne systemic infection

Question 7

What is an Injectisome?

Answer 7

Mechanism for injecting toxins into host cells

Question 8

What are pathogenicity islands?

What are the two types in S. enterica serovar typhimurium? (SPI1 and SPI2)

Answer 8

Genes that direct invasion are clustered on the chromosome as pathogenicity islands

SPI1- encodes proteins promoting invasion forming an injectisome
SPI2- genes that promote a more systemic disease
Slide 16

Question 9

What is coagulase, streptokinase, and hyaluronidase?

Answer 9

Coagulase- induces fibrin clotting
Streptokinase- dissolves fibrin clots
Slide 19
Hyaluronidase- dissolves hyaluronic acid (the glue that cements cells together) in connective tissue
Slide 18

Question 10

What are exotoxins?

What are three categories?

Answer 10

Toxic proteins secreted by the pathogen as it grows
Three categories:
Cytolytic toxins
AB toxins
Superantigen toxins

Question 11

What are cytolytic toxins?

What are hemolysins?

Answer 11

Degrade cytoplasmic membrane integrity which leads to cell lysis and death
Hemolysins are toxins that lyse red blood cells

Slide 23

Question 12

What are the 5 membrane disrupting toxins? (cytolytic toxins)

Answer 12

Streptolysin 
Pneumolysin 
Alpha-toxin
These 3 assemble into pores in cell membranes
Alpha-toxin
Phospholipase C
Beta-toxin
These 3 degrade cell membrane phospholipids

Question 13

What are AB toxins?

4 types?

Answer 13

A and B subunits
Bind host to cell receptor (B subunit) and transferring damaging agent (A subunit) across cell membrane
Slide 27

Cholera toxin
Tetanus toxin
Botulinum toxin
Diphtheria toxin

Slide 28-30

Question 14

What are enterotoxins?

Answer 14

AB toxin
Activity effects small intestine
Cause mass secretion of fluid into intestinal lumen (vomiting and diarrhea)

Question 15

What are endotoxins?

Answer 15

Lipopolysaccharide portion of cell envelope of some gram negative bacteria which is a toxin when solubilized
Less toxic than exotoxins but can cause death

Question 16

What is a compromised host?

Answer 16

One or more resistance mechanisms are inactive
Age can cause this
Stress can too
Diet can
Certain genetic conditions

Look at barriers to infection slide 35