Question 1

Which of the following best describes the function of the B component in an A-B exotoxin?

Accepted Answer

It binds to the host cell, facilitating entry of the A component.

Question 2

A patient develops severe muscle paralysis after consuming improperly canned food. Which toxin is most likely responsible, and what is its mechanism?

Accepted Answer

Botulinum toxin; inhibits release of acetylcholine from nerve cells.

Question 3

Which pathogenic factor allows Streptococcus pyogenes to resist phagocytosis and attach to host cells?

Accepted Answer

M protein

Question 4

During septic shock caused by Gram-negative bacteria, which molecule is primarily responsible for triggering the release of TNF from phagocytes?

Accepted Answer

Lipid A of LPS

Question 5

Which of the following is a characteristic of exotoxins?

Accepted Answer

They are proteins, usually heat labile, and often highly toxic.

Question 6

A patient with a Streptococcus pyogenes infection develops a massive immune response due to superantigen production. What is the most likely outcome?

Accepted Answer

Non-specific proliferation of T cells and cytokine release, including TNF.

Question 7

Which enzyme produced by bacteria breaks down fibrin clots, aiding in the spread of infection?

Accepted Answer

Kinase

Question 8

Neisseria gonorrhoeae uses which structure to attach to host cells?

Accepted Answer

Fimbriae

Question 9

Which pathogenic factor is responsible for breaking down hyaluronic acid in connective tissue, facilitating bacterial spread?

Accepted Answer

Hyaluronidase

Question 10

A patient with Gram-negative septicemia is at risk for shock due to increased capillary permeability. Which equation best describes the relationship between blood pressure ($$BP$$), blood volume ($$V$$), and systemic infection ($$I$$)?

Accepted Answer

$$BP \propto V - I$$

Question 11

Which bacterial factor is most likely to help a pathogen acquire iron from the host?

Accepted Answer

Siderophore

Question 12

Which of the following is NOT a portal of entry for pathogens?

Accepted Answer

Blood pressure

Question 13

Which pathogenic factor destroys white blood cells, aiding in immune evasion?

Accepted Answer

Leukocidin

Question 14

Which of the following statements about endotoxins is correct?

Accepted Answer

They are heat stable and composed of lipid A from LPS.

Question 15

A patient with cholera experiences massive loss of electrolytes and water. Which type of toxin is responsible, and what is its mechanism?

Accepted Answer

Enterotoxin; disrupts membrane function in intestinal epithelia.

Question 16

Which equation best represents the relationship between virulence ($$V$$), pathogenicity ($$P$$), and likelihood of disease ($$D$$)?

Accepted Answer

$$D = P 	imes V$$

Question 17

Which enzyme produced by bacteria helps them evade the immune system by breaking down antibodies?

Accepted Answer

IgA protease

Question 18

Which pathogenic factor is most likely to cause the destruction of red blood cells?

Accepted Answer

Hemolysin

Question 19

Which of the following is a real-life consequence of superantigen production by Staphylococcus aureus?

Accepted Answer

Toxic shock syndrome due to massive cytokine release.

Question 20

Which cell wall component allows Mycobacteria to resist phagocytosis?

Accepted Answer

Mycolic acid

Mechanisms of Pathogenicity: Study Guide for Chapter 15

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