Self Quiz for "Bacterial Pathogenesis: Factors that Damage the Host"
2. Producing Harmful Exotoxins
c. Type III Toxins that Interfere with Host Cell Function

Study the material in this section and then write out the answers to these questions.
Do not just click on the answers and write them out. This will not test your understanding of this tutorial.

1. State the functions of the A component and the B component in A-B toxins. (ans).

2. Match the following descriptions with the exotoxin:

_____ Produced by certain strains of Escherichia coli such as E. coli O157:H7. These toxins kill intestinal epithelial cells of the colon and cause bloody diarrhea. Less commonly, the toxins enter the blood and are carried to the kidneys where they damage endothelial cells of the blood vessels and cause hemolytic uremic syndrome (HUS). (ans)

_____ Produced by a species of Clostridium. This is a neurotoxin that acts peripherally on the autonomic nervous system. This toxin binds to and enters the presynaptic neuron and blocks its release of acetylcholine. This causes a flaccid paralysis, a weakening of the involved muscles. (ans)

_____ Produced by a species of Clostridium. This is a neurotoxin that binds to inhibitory interneurons of the spinal cord and blocks their release of inhibitor molecules.The toxin, by blocking the release of inhibitors, keeps the involved muscles in a state of contraction and leads to spastic paralysis, a condition where opposing flexor and extensor muscles simultaneously contract. (ans)

_____ At low levels, this toxin inhibits the release of proinflammatory cytokines such as interleukin-1 (IL-1), tumor necrosis factor-alpha, (TNF-alpha), and NO. This may initially reduce immune responses against the organism and its toxins. But at high levels, it is cytolytic for macrophages, causing release of high levels of interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and NO. Excessive release of these cytokines can lead to a massive inflammatory response and the shock cascade, similar to septic shock. (ans)

2. Multiple Choice (ans)

• RETURN TO "BACTERIAL PATHOGENESIS: FACTORS THAT DAMAGE THE HOST - PRODUCING HARMFUL EXOTOXINS: TYPE III TOXINS THAT INTERFERE WITH HOST CELL FUNCTIONS"

• RETURN TO UNIT 3 TABLE OF CONTENTS

Gary E. Kaiser, Ph.D.
Professor of Microbiology
The Community College of Baltimore County, Catonsville Campus
This work is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work The Grapes of Staph at https://cwoer.ccbcmd.edu/science/microbiology/index_gos.html.