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 inhaling droplets containing Streptococcus pneumoniae. Which portal of entry did the pathogen use?

Accepted Answer

Mucous membranes of the respiratory tract

Question 3

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

Accepted Answer

Respiratory tract

Question 4

If a pathogen requires an ID$_{50}$ of 10 endospores to infect through the skin, but 250,000 endospores to infect via ingestion, what does this indicate about the preferred portal of entry?

Accepted Answer

The pathogen is more virulent when entering through the skin.

Question 5

Which equation correctly represents the calculation for LD$_{50}$?

Accepted Answer

$LD_{50}$ is the dose at which 50\% of a sample population dies.

Question 6

Which bacterial structure is most directly involved in adherence to host tissues?

Accepted Answer

Fimbriae

Question 7

A patient is infected with Neisseria gonorrhoeae. Which cell wall component allows this bacterium to attach to host cells?

Accepted Answer

Opa protein

Question 8

Which enzyme produced by bacteria digests hyaluronic acid, allowing the pathogen to spread through host tissues?

Accepted Answer

Hyaluronidase

Question 9

Influenza virus can evade the host immune system by altering its surface antigens. This process is known as:

Accepted Answer

Antigenic variation

Question 10

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

Accepted Answer

Use of actin filaments

Question 11

Biofilms contribute to pathogenicity by:

Accepted Answer

Shielding bacteria from phagocytosis

Question 12

Siderophores are important for bacterial pathogenicity because they:

Accepted Answer

Bind iron more tightly than host iron-binding proteins

Question 13

Which of the following statements about exotoxins is TRUE?

Accepted Answer

Exotoxins are proteins produced and secreted by bacteria, often highly specific for their targets.

Question 14

A-B toxins have two components. What is the function of the B component?

Accepted Answer

It binds to the host cell receptor.

Question 15

Which type of exotoxin causes an intense immune response due to the release of cytokines from T cells?

Accepted Answer

Superantigen

Question 16

Endotoxins are associated with which part of gram-negative bacteria?

Accepted Answer

Lipid A portion of lipopolysaccharides (LPS)

Question 17

Which laboratory assay is used to detect the presence of endotoxins?

Accepted Answer

Limulus amebocyte lysate (LAL) assay

Question 18

A patient develops symptoms of fever, chills, and shock after a gram-negative bacterial infection. Which mechanism is most likely responsible?

Accepted Answer

Release of endotoxins during bacterial multiplication and death

Question 19

Which of the following is a consequence of lysogenic conversion in bacteria?

Accepted Answer

Change in bacterial characteristics due to incorporation of a prophage

Question 20

Which cytopathic effect is commonly used to diagnose rabies virus infection?

Accepted Answer

Creation of Negri bodies in neurons

Microbial Mechanisms of Pathogenicity – Chapter 15 Study Notes

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