Question 1

Which of the following best describes the difference between infection and disease?

Accepted Answer

Infection refers to the invasion or colonization of the body by pathogens, while disease refers to an abnormal state in which the body is not performing normal functions.

Question 2

Which of the following is an example of mutualism in the human body?

Accepted Answer

Bacteria in the human colon producing vitamins for the host.

Question 3

A patient develops a disease after their immune system is suppressed by chemotherapy. The causative agent is a member of their normal microbiota. This is an example of:

Accepted Answer

An opportunistic infection.

Question 4

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

Accepted Answer

Liver

Question 5

Which of the following is a correct sequence of Koch’s postulates?

Accepted Answer

1. The same pathogen must be present in every case of the disease. 2. The pathogen must be isolated and grown in pure culture. 3. The pathogen must cause the disease when inoculated into a healthy animal. 4. The pathogen must be re-isolated from the inoculated animal.

Question 6

Which of the following is a distinguishing feature of exotoxins compared to endotoxins?

Accepted Answer

Exotoxins are proteins, usually with two parts (A-B), and are highly toxic even in small amounts.

Question 7

A patient presents with fever, shock, and disseminated intravascular coagulation after a gram-negative bacterial infection. Which virulence factor is most likely responsible?

Accepted Answer

Endotoxin (Lipid A of LPS)

Question 8

Which of the following is a correct statement about the Limulus amebocyte lysate (LAL) assay?

Accepted Answer

It detects the presence of endotoxins by causing amebocytes from horseshoe crab blood to lyse and form a clot.

Question 9

Which of the following is an example of vehicle transmission?

Accepted Answer

A person contracts cholera after drinking contaminated water.

Question 10

Which of the following best describes the prodromal period of an infectious disease?

Accepted Answer

It is the period with mild signs or symptoms before the illness becomes most severe.

Question 11

Which of the following is a function of the Centers for Disease Control and Prevention (CDC)?

Accepted Answer

Collecting and analyzing data on notifiable infectious diseases in the United States.

Question 12

A hospital patient develops diarrhea after receiving broad-spectrum antibiotics, which suppress normal microbiota and allow Clostridium difficile to thrive. This is an example of:

Accepted Answer

A superinfection

Question 13

Which of the following is a correct match between a disease and its mode of zoonotic transmission?

Accepted Answer

Rabies – bite of infected animal

Question 14

Which of the following is a sign, not a symptom, of disease?

Accepted Answer

Fever

Question 15

Which of the following best describes the role of a bacterial capsule as a virulence factor?

Accepted Answer

It prevents phagocytosis by making the bacterium slippery and difficult for phagocytes to engulf.

Question 16

A patient is infected with a bacterium that produces an A-B exotoxin. Which of the following best describes the mechanism of this toxin?

Accepted Answer

The B component binds to a host cell receptor, allowing the A component to enter and disrupt cell function.

Question 17

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

Accepted Answer

They are heat stable and can withstand autoclaving.

Question 18

Which of the following is an example of analytical epidemiology?

Accepted Answer

Comparing the rate of illness between people who ate green beans and those who did not after an outbreak.

Question 19

Which of the following is a predisposing factor that can make the body more susceptible to disease?

Accepted Answer

Inherited traits such as the sickle cell gene

Infection, Infectious Diseases, and Epidemiology: Core Concepts and Mechanisms

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