Question 1

Which of the following statements best explains the 'eclipse period' observed in the viral one-step growth curve?

Accepted Answer

It is the phase after viral entry but before new virions are detectable outside the host cell.

Question 2

A patient is exposed to Bacillus anthracis by three different routes: skin, inhalation, and ingestion. Based on the ID$$_{50}$$ values, which route is most likely to result in infection with the smallest number of endospores?

Accepted Answer

Skin

Question 3

Botulinum toxin has an LD$$_{50} of 0.03 ng/kg$$, Shiga toxin has an LD$$_{50} of 250 ng/kg$$, and Staphylococcal enterotoxin has an LD$$_{50} of 1350 ng/kg. $$Which statement is correct regarding their relative potencies?

Accepted Answer

Botulinum toxin is the most potent because it requires the smallest dose to be lethal.

Question 4

Which of the following best describes the mechanism by which endotoxins cause fever in the host?

Accepted Answer

Endotoxins stimulate macrophages to release cytokines such as IL-1 and TNF-$$\alpha$$, which act on the hypothalamus.

Question 5

A patient develops chickenpox and, years later, experiences shingles. Which of the following best explains this pattern of infection?

Accepted Answer

Chickenpox is an acute infection, and shingles is a reactivation of a latent infection.

Question 6

Which enzyme produced by bacteria allows them to break down collagen and invade deeper tissues?

Accepted Answer

Collagenase

Question 7

Which of the following statements about prion diseases is correct?

Accepted Answer

Prion diseases are caused by misfolded proteins that induce normal proteins to misfold.

Question 8

Which structure on a pathogen is most directly involved in adherence to host cells?

Accepted Answer

Fimbriae with adhesins

Question 9

Trypanosomes are able to persist in a host by changing their surface proteins. What is this process called, and why does it help the pathogen?

Accepted Answer

Antigenic variation; it allows the pathogen to evade the host's immune response.

Question 10

A patient is diagnosed with septic shock after a gram-negative bacterial infection. Which of the following best explains the underlying cause of the shock?

Accepted Answer

Endotoxins trigger the release of TNF-$$\alpha$$ from macrophages, increasing capillary permeability and causing fluid loss.

Question 11

Which of the following is a correct match between a portal of entry and an example of a disease transmitted through that portal?

Accepted Answer

Mucous membrane (respiratory tract) – Measles

Question 12

Which of the following best describes the function of siderophores in bacterial pathogenesis?

Accepted Answer

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

Question 13

A patient is exposed to a pathogen with an ID$$_{50} of 1000 $$cells and an LD$$_{50} of 10$$,000 cells. What does this mean?

Accepted Answer

1000 cells are required to infect 50% of the population, and 10,000 cells are required to kill 50% of the population.

Question 14

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

Accepted Answer

Can be converted to toxoids for use in vaccines

Question 15

Which of the following best explains why biofilms are problematic in hospital settings?

Accepted Answer

Biofilms protect bacteria from antibiotics and immune responses.

Question 16

Which of the following is an example of a superantigen and its effect?

Accepted Answer

Streptococcal toxin; causes massive cytokine release and toxic shock

Question 17

A patient develops a local infection that later spreads to the heart. What is the best term for the infection in the heart?

Accepted Answer

Focal infection

Question 18

Which of the following is a correct description of the action of an A-B exotoxin?

Accepted Answer

The B component binds to the host cell, and the A component inhibits protein synthesis.

Question 19

Which of the following is NOT a method by which bacteria can evade destruction by phagocytes?

Accepted Answer

Producing siderophores to acquire iron

Question 20

Which of the following is the best example of a vehicle transmission of disease?

Accepted Answer

A person develops cholera after drinking contaminated water.

Comprehensive Study Guide: Viruses, Disease, and Pathogenicity (Chapters 13–15)

Study Guide - Practice Questions

Study Guide - Flashcards