Chapter 16: Host-Microbe Interactions: Damage to the Host

Question 1

Bacteria can do direct or indirect damage to the host. What is indirect damage?

Answer 1

• inducing an immune response and causing inflammation

Question 2

Bacteria can do direct or indirect damage to the host. What is direct damage?

Answer 2

• production of exoenzymes or toxins

Question 3

What is a toxin?

Answer 3

• poisonous substance produced by a microorganism

Question 4

what are exotoxins?

Answer 4

• Proteins excreted by bacteria

Question 5

what are two characteristics of exotoxins?

Answer 5

• generally heat sensitive
• can be extremely toxic, among most lethal substance is known

Question 6

Why is Clostridium botulinum an exotoxin?

Answer 6

• causes botulism
• botulinum toxin 1 mig can kill 1 mil guinea pigs

Question 7

What are the 3 categories of exotoxins?

Answer 7

1. Neurotoxins
2. enterotoxins
3. Cytotoxins

Question 8

What are neurotoxins?

Answer 8

• interfere with nerve impulses

Question 9

what are the 2 types of neurotoxins?

Answer 9

1. Botulinum toxin
2. Tetanus toxin

Question 10

What does the botulinum toxin cause? (3)

Answer 10

• flaccid paralysis
• muscles permanent relax
• heart stops beating, breathing stops

Question 11

What does the tetanus toxin cause? (4)

Answer 11

• rigid paralysis
• uncontrollable muscle contractions (spasms)
• results in lockjaw
• death usually occurs due to spasms of respiratory muscles

Question 12

What are enterotoxins?

Answer 12

• modify intestinal cells so they continuously secrete water
  ex. Cholera toxin causes severe watery diarrhea

Question 13

What are cytotoxins?

Answer 13

• general cell killers

Question 14

How is the diphteria toxin (C. diphtheriae) a cytotoxin?

Answer 14

• interferes with proteins synthesis killing cells
• kills the cells in the respiratory tract

Question 15

Lipopolysaccharide is an ____ (endotoxin/exotoxin)

Answer 15

endotoxin

Question 16

What is lipopolysaccharide? (2)

Answer 16

• part of the outer membrane of gram negative bacteria

Question 17

Do endotoxins cause problems when embedded into the outer membrane?

Answer 17

no

Question 18

What do endotoxins trigger?

Answer 18

• released when bacteria die
• can trigger fever, inflammation, hemorrhaging, shock

Question 19

Which are more potent: exotoxins or endotoxins?

Answer 19

• exotoxins
• endotoxins are not as potent, so you need much more to cause symptoms

Question 20

explain why Salmonellosis (S. enterica) is an endotoxin (3)

Answer 20

• food borne illness
• symptoms causes by endotoxin released from millions of dying bacteria
• antibiotic treatment can do more harm than good

Question 21

In summary, what are exotoxins and what do they do? (3)

Answer 21

• proteins
• released outside the cell
• extremely toxic and often lethal

Question 22

In summary, what are endotoxins? (3)

Answer 22

• LPS
• only released when bacteria die
• not as toxic and not usually lethal