Question 1

Which of the following best describes the difference between pathogenicity and virulence?

Accepted Answer

Pathogenicity is the ability to cause disease, while virulence is the degree of pathogenicity.

Question 2

A patient develops a severe infection after a deep puncture wound. Which portal of entry did the pathogen most likely use?

Accepted Answer

Parenteral route

Question 3

Which of the following best explains why the respiratory tract is the most common portal of entry for pathogens?

Accepted Answer

It is constantly exposed to airborne particles and has a large surface area.

Question 4

The $$ID_{50}$$ for Bacillus anthracis via the skin is 10–50 endospores, while via inhalation it is 10,000–20,000 endospores. What does this indicate about the skin as a portal of entry?

Accepted Answer

The skin is a more efficient portal of entry for B. anthracis than inhalation.

Question 5

A drug that binds to mannose on human cells would most likely interfere with which step of microbial infection?

Accepted Answer

Adherence of the pathogen to host cells

Question 6

Which of the following is a function shared by both capsules and M proteins in bacterial pathogenicity?

Accepted Answer

They both help bacteria resist phagocytosis.

Question 7

Why would a bacterium not produce both coagulase and kinase enzymes simultaneously?

Accepted Answer

Coagulase forms clots to protect bacteria, while kinase dissolves clots; simultaneous production would counteract their effects.

Question 8

Which of the following best describes antigenic variation?

Accepted Answer

Pathogens alter their surface antigens to evade the host immune response.

Question 9

How do invasins produced by bacteria facilitate infection?

Accepted Answer

They rearrange actin filaments of the host cytoskeleton, causing membrane ruffling and bacterial engulfment.

Question 10

Which of the following mechanisms allows Shigella and Listeria to move from one host cell to another?

Accepted Answer

Using actin polymerization to propel themselves through the cytoplasm

Question 11

What is the primary function of siderophores in bacterial pathogenicity?

Accepted Answer

To bind iron more tightly than host proteins, allowing bacteria to acquire essential iron

Question 12

Which of the following statements best distinguishes exotoxins from endotoxins?

Accepted Answer

Exotoxins are proteins secreted by bacteria, while endotoxins are lipid A components of the outer membrane of gram-negative bacteria.

Question 13

A patient develops fever and shock after receiving a sterile intravenous solution. The solution was contaminated with endotoxin but not live bacteria. Which test should have been used to detect the contamination?

Accepted Answer

Limulus amebocyte lysate (LAL) assay

Question 14

Which of the following is a mechanism of action for A-B exotoxins?

Accepted Answer

The B component binds to the host cell, and the A component inhibits a cellular function such as protein synthesis.

Question 15

Which of the following is a cytopathic effect of viral infection that can lead to cancer?

Accepted Answer

Transformation of host cells resulting in loss of contact inhibition

Question 16

Which virulence factor allows Cryptococcus neoformans to evade phagocytosis?

Accepted Answer

Capsule

Question 17

A patient develops paralytic shellfish poisoning after eating contaminated mollusks. Which type of microorganism and toxin are responsible?

Accepted Answer

Algae producing saxitoxin

Question 18

Which of the following is the most commonly used portal of exit for respiratory pathogens?

Accepted Answer

Respiratory tract via coughing and sneezing

Question 19

Which of the following best explains why the influenza vaccine does not provide long-term protection?

Accepted Answer

The influenza virus undergoes antigenic variation, changing its surface antigens frequently.

Microbial Mechanisms of Pathogenicity: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards