Question 1

Which of the following best describes the difference between disinfection and sterilization?

Accepted Answer

Disinfection reduces the microbial load but does not eliminate all microbes, while sterilization kills or removes all living organisms.

Question 2

A hospital is deciding between using dry heat and moist heat to sterilize surgical instruments. Which statement is correct regarding these methods?

Accepted Answer

Moist heat sterilization (such as autoclaving) is generally more effective and requires lower temperatures and shorter times than dry heat.

Question 3

Which of the following best explains why antibiotics that inhibit cell wall synthesis have high selective toxicity?

Accepted Answer

They inhibit enzymes unique to bacterial cell wall synthesis, which are absent in human cells.

Question 4

A patient is prescribed a broad-spectrum antibiotic. What is a potential negative consequence of this treatment?

Accepted Answer

It can wipe out beneficial microbiota, increasing the risk of secondary infections.

Question 5

Which of the following is a mechanism by which bacteria can become resistant to antibiotics?

Accepted Answer

Producing enzymes that inactivate the antibiotic, such as $$\beta-$$lactamase.

Question 6

Why is it important to complete the full course of an antibiotic treatment, even if symptoms improve before the medication is finished?

Accepted Answer

Completing the course kills both susceptible and most spontaneous mutant bacteria, reducing the risk of resistance.

Question 7

Which of the following best describes the mode of action of sulfonamide antibiotics?

Accepted Answer

They act as growth factor analogs, competitively inhibiting enzymes involved in folic acid synthesis.

Question 8

A laboratory is testing the effectiveness of a new antimicrobial agent using the minimum inhibitory concentration (MIC) method. Which of the following best describes how the MIC is determined?

Accepted Answer

By finding the lowest concentration of the agent that prevents visible microbial growth.

Question 9

Why do antibiotics that inhibit protein synthesis sometimes affect human mitochondria?

Accepted Answer

Mitochondria contain 70S ribosomes, which are similar to bacterial ribosomes targeted by these antibiotics.

Question 10

Which of the following is a reason why using a narrow-spectrum antibiotic is preferred over a broad-spectrum antibiotic when possible?

Accepted Answer

Narrow-spectrum antibiotics are less likely to select for resistance in non-target bacteria.

Question 11

A food manufacturer wants to prevent microbial growth in canned foods. Which method is most effective for this purpose?

Accepted Answer

Increasing the acidity (lowering pH) to inhibit microbial growth.

Question 12

Which of the following best explains why high osmolarity environments inhibit microbial growth?

Accepted Answer

High osmolarity draws water out of microbial cells, leading to dehydration and inhibition of growth.

Question 13

Which of the following is a property of an ideal chemotherapeutic agent?

Accepted Answer

High selective toxicity and a narrow spectrum of activity.

Question 14

A patient with a bacterial infection is treated with an antibiotic that targets DNA gyrase. Why does this drug have selective toxicity?

Accepted Answer

DNA gyrase is unique to bacteria and not found in human cells.

Question 15

Which of the following is NOT a common mechanism by which bacteria develop resistance to antibiotics?

Accepted Answer

Increasing the rate of antibiotic uptake into the cell.

Question 16

Why does the presence of a biofilm increase bacterial resistance to antibiotics?

Accepted Answer

Biofilms slow antibiotic diffusion and promote dormancy in some cells, making them less susceptible.

Question 17

Which of the following best explains why overprescribing antibiotics contributes to the emergence of antibiotic-resistant bacteria?

Accepted Answer

It increases the selection pressure for resistant strains by exposing more bacteria to antibiotics.

Question 18

A patient is infected with a bacterium that produces $$\beta-$$lactamase. Which class of antibiotics is most likely to be inactivated by this enzyme?

Accepted Answer

Penicillins

Question 19

Which of the following is a reason why antibiotics are sometimes ineffective against bacteria in a dormant state within a biofilm?

Accepted Answer

Antibiotics only target actively growing and dividing cells.

Question 20

Which of the following best describes the effect of a bacteriostatic agent on a bacterial population?

Accepted Answer

It reversibly inhibits bacterial growth; growth resumes when the agent is removed.

Control of Microbial Growth and Antibiotic Resistance

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