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 pneumonia after being bitten by an insect. Which portal of entry did the pathogen most likely use?

Accepted Answer

Parenteral route

Question 3

Which of the following is the most common portal of entry for pathogens?

Accepted Answer

Respiratory tract

Question 4

If the $$ID_{50}$$ for Bacillus anthracis via inhalation is 15,000 endospores, what does this value represent?

Accepted Answer

The number of endospores required to infect 50% of a sample population via inhalation.

Question 5

Which of the following best explains why Streptococcus pneumoniae with a capsule is more virulent than without?

Accepted Answer

The capsule impairs phagocytosis by host cells.

Question 6

A bacterial pathogen produces coagulase. What is the most likely effect of this enzyme?

Accepted Answer

It forms a protective fibrin clot around the bacteria, helping it evade host defenses.

Question 7

Which of the following is an example of antigenic variation?

Accepted Answer

Neisseria gonorrhoeae changing its surface proteins to evade antibodies.

Question 8

How do siderophores contribute to bacterial pathogenicity?

Accepted Answer

They bind iron more tightly than host proteins, allowing bacteria to acquire essential nutrients.

Question 9

Which of the following statements about exotoxins is TRUE?

Accepted Answer

Exotoxins are proteins, often with A-B structure, and can be inactivated to form toxoids for vaccines.

Question 10

A patient develops fever and shock after a gram-negative bacterial infection. Which component is most likely responsible?

Accepted Answer

Lipid A of lipopolysaccharide (endotoxin)

Question 11

Which laboratory test is used to detect the presence of endotoxins in a pharmaceutical product?

Accepted Answer

Limulus amebocyte lysate (LAL) assay

Question 12

Which of the following is a cytopathic effect (CPE) caused by viral infection?

Accepted Answer

Formation of syncytia (multinucleated giant cells)

Question 13

Which of the following is a property of endotoxins but NOT exotoxins?

Accepted Answer

They are heat stable and can withstand autoclaving at $$121^{\circ}C$ for 1 hour.

Question 14

A patient presents with symptoms of paralytic shellfish poisoning after eating contaminated shellfish. Which microbial product is responsible?

Accepted Answer

Saxitoxin produced by dinoflagellates

Question 15

Which of the following mechanisms allows Trypanosoma brucei gambiense to evade the host immune system?

Accepted Answer

Antigenic variation

Question 16

Which of the following is a multi-step process that best describes the action of an A-B exotoxin?

Accepted Answer

B component binds to host cell, A component enters and disrupts cell function.

Question 17

Which of the following is a function of alpha and beta interferons produced by virally infected cells?

Accepted Answer

They protect neighboring cells by inhibiting viral protein synthesis and inducing apoptosis.

Question 18

Which of the following is a property of biofilms that contributes to their role in infection?

Accepted Answer

Biofilms resist antibiotics and phagocytosis due to their extracellular polymeric substance (EPS).

Question 19

A patient is diagnosed with gas gangrene. Which enzyme produced by the causative organism is most responsible for the rapid spread of infection through tissue?

Accepted Answer

Collagenase

Question 20

Which of the following is a correct statement about the portals of exit for pathogens?

Accepted Answer

They are generally the same as the portals of entry.

Microbial Mechanisms of Pathogenicity: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards