Q: Which of the following is a correct formula for calculating prevalence?

$$\text{Prevalence} = \frac{\text{Total number of cases in population}}{\text{Total number of persons in population}} \times 100$$

Question 1

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

Accepted Answer

Colonization is the long-term presence of microbes without causing harm; infection is when microbes invade tissues and multiply; disease is when the cumulative effects of infection damage or disrupt tissues and organs.

Question 2

Which of the following body sites was previously thought to be sterile but is now known to harbor at least some normal microbiota or their DNA?

Accepted Answer

Breast milk

Question 3

A newborn baby’s initial microbiome is influenced by all of the following EXCEPT:

Accepted Answer

Sterilized baby formula

Question 4

Which of the following statements about the Human Microbiome Project (HMP) is FALSE?

Accepted Answer

It has demonstrated that the human microbiome contains fewer protein-encoding genes than human cells.

Question 5

Which of the following is the best definition of 'infectious dose' ($$ID$$)?

Accepted Answer

The minimum number of microbes necessary to cause an infection to proceed.

Question 6

A patient develops pneumonia after an influenza infection. This is an example of:

Accepted Answer

A polymicrobial infection

Question 7

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

Accepted Answer

Toxic in minute amounts

Question 8

Which of the following is an example of a nonliving reservoir for infectious agents?

Accepted Answer

Soil contaminated with Clostridium tetani

Question 9

A disease that is highly communicable, especially through direct contact, is best described as:

Accepted Answer

Contagious

Question 10

Which of the following is NOT a common portal of exit for infectious diseases?

Accepted Answer

Liver

Question 11

Which of the following best describes the acute phase of an infectious disease?

Accepted Answer

The period when the infectious agent multiplies at high levels and symptoms are most severe

Question 12

Which of the following is a correct formula for calculating prevalence?

Accepted Answer

$$	ext{Prevalence} = \frac{	ext{Total number of cases in population}}{	ext{Total number of persons in population}} 	imes 100$$

Question 13

Which of the following is NOT a step in the process by which a microbe causes disease in a host?

Accepted Answer

Producing antibodies against the host

Question 14

A hospital patient develops a urinary tract infection after catheterization. This is best described as:

Accepted Answer

A healthcare-associated infection (HAI)

Question 15

Which of the following is a reason why Koch’s postulates may NOT be appropriate for establishing causation in some diseases?

Accepted Answer

Some infectious agents cannot be readily isolated or grown in the laboratory.

Question 16

Which of the following best describes herd immunity?

Accepted Answer

When a significant portion of a population is immune, limiting further disease spread

Question 17

Which of the following is an example of a vector transmission of disease?

Accepted Answer

A mosquito transmitting malaria

Question 18

Which of the following is a correct statement about the relationship between infectious dose ($$ID) $$and virulence?

Accepted Answer

Microorganisms with a smaller infectious dose have greater virulence.

Question 19

Which of the following is an example of a sign, rather than a symptom, of disease?

Accepted Answer

Edema

Question 20

A propagated epidemic is best characterized by:

Accepted Answer

A sustained increase in cases due to person-to-person transmission

Interactions Between Microbes and Humans: Pathogenesis, Transmission, and Epidemiology

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