Chapter 15 - Microbial Mechanisms of Pathogenicity

Question 1

What are 4 ways bacteria damage host cells?

Answer 1

1) Using nutrients 2) direct damage in the vicinity of invasion 3) producing toxins 4) inducing hypersensitivity reactions

Question 2

How do bacteria use a host’s nutrients?

Answer 2

Siderophores are proteins secreted by bacteria that take iron from iron transport systems.

Question 3

How do cells cause direct damage to host cells?

Answer 3

As pathogens multiply, the host cell usually ruptures.

Question 4

How do bacterial toxins damage host cells?

Answer 4

bacterial toxins can prohibit protein synthesis, destroy blood cells, and disrupt nervous systems.

Question 5

What are the two types of toxins?

Answer 5

Endotoxins and Exotoxins

Question 6

Write a brief note on exotoxins?

Answer 6

Exotoxins are enzymes released by bacteria that easily diffuse through the body. They inhibit strategic metabolic functions of the host. They cause specific symptoms for each disease.

Question 7

What does disease specificity mean?

Answer 7

Exotoxins produce the specific signs of each disease

Question 8

Write a brief note on endotoxins.

Answer 8

Endotoxins are lipopolysaccharides that are released from the cell wall of gram negative bacteria. They cause the over production and release of cytokines from T cells.

Question 9

How does the body provide immunity to exotoxins?

Answer 9

antitoxins provide immunity against exotoxins.

Question 10

What are toxoids and how are they beneficial?

Answer 10

toxoids are inactivated toxins, often by heat or chemicals . When injected into the body, they don’t cause disease but still stimulate the production of antitoxins.

Question 11

How are exotoxins named?

Answer 11

1) the type of host cell attacked 2) the disease they are associated with 3) the bacteria that produces them

Question 12

What are the 3 types of exotoxins?

Answer 12

1) A-B toxins 2) membrane-disrupting toxins 3) superantigen

Question 13

Write a brief note on A-B toxins?

Answer 13

A-B toxins are composed of two polypeptide parts (an active and a binding part) invaginated by the host cell. The A part alters the function of the host cell and the B component is released for reuse.

Question 14

Write a brief note on membrane-disrupting toxins. Include two examples.

Answer 14

Membrane-disrupting toxins cause the lysis of host cells by disrupting their plasma membranes. Two types of M-D toxins are 1) leukocidins (kill WBC) 2) hemolysins (Kill RBC)

Question 15

Write a brief note on superantigens

Answer 15

superantigens are bacterial proteins cause the overproduction of T cells which gives rise to severe symptoms.

Question 16

What is the effect of Diphtheria Toxin?

Answer 16

Diphtheria Toxins inhibit protein synthesis

Question 17

What is the effect of Erythrogenic Toxins?

Answer 17

Erythrogenic toxins damage the plasma membranes of blood capillaries.

Question 18

What is the relation between Endotoxins and Lipid A?`

Answer 18

Lipid A causes symptoms in a host after bacteria have been killed. Lipid A is the lipid portion of an endotoxin.

Question 19

Apart from the overproduction and release of cytokines, what is a secondary effect of endotoxins?

Answer 19

Endotoxins cause the activation of blood clotting proteins which result in decreased blood supply.

Question 20

How do aspirin and acetaminophen reduce fevers?

Answer 20

By inhibiting the synthesis of prostaglandins.

Question 21

What is shock?

Answer 21

life-threatening decrease in blood pressure.

Question 22

What is the term for bacterial induced shock?

Answer 22

septic shock?

Question 23

What are R factors?

Answer 23

Plasmids that contribute to antibiotic resistance.

Question 24

In addition to antibiotic resistance, how else can plasmids affect a microbe?

Answer 24

Plasmids can carry information that can contribute to pathogenicity and virulence

Question 25

How does entry to a host cell contribute to host defense evasion?

Answer 25

Host defense cannot enter host cells

Question 26

What is cytopathic effect?

Answer 26

The visible effects of viral infection

Question 27

What are the three ways viruses can cause death?

Answer 27

1) multiplying in large numbers 2) affecting permeability 3) inhibiting synthesis

Question 28

How do fungi cause disease?

Answer 28

Some fungal metabolic products are toxic, some secrete proteases,

Question 29

How do Protozoa cause disease?

Answer 29

Protozoan waste products cause disease

Question 30

How do helminths cause disease in their hosts?

Answer 30

Helminths cause cellular damage by using host tissue for their own growth or producing large parasitic masses

Question 31

How do algae cause disease?

Answer 31

Algae produce neurotoxins

Question 32

What are the most common portals of exit?

Answer 32

Respiratory and GI tract