Question 1

Which of the following best explains why physicians can safely prescribe some antimicrobial drugs that are potentially harmful to humans?

Accepted Answer

Because the drugs are administered in doses that are selectively toxic to microbes but not to human cells.

Question 2

A patient is prescribed a drug that inhibits protein synthesis in bacteria. Which of the following is the most likely mechanism of action for this drug?

Accepted Answer

It interferes with ribosomal function, preventing translation.

Question 3

Which of the following is a potential consequence of using a broad-spectrum antimicrobial drug?

Accepted Answer

It may lead to secondary or superinfections due to the reduction of normal flora.

Question 4

A Kirby-Bauer test is performed to determine the susceptibility of a bacterial strain to various antibiotics. What does a large zone of inhibition around a disk indicate?

Accepted Answer

The antibiotic is highly effective against the bacteria.

Question 5

Which of the following best describes the minimum inhibitory concentration (MIC) test?

Accepted Answer

It determines the lowest concentration of an antimicrobial that prevents visible growth of a microorganism.

Question 6

A patient is given an antimicrobial drug intravenously. According to the pharmacokinetics of drug administration, which of the following best describes the expected blood concentration profile?

Accepted Answer

A rapid spike to a high concentration, then a gradual decrease.

Question 7

Which of the following is the best definition of the therapeutic index?

Accepted Answer

The ratio of the dose of a drug that can be tolerated to the drug's effective dose.

Question 8

A patient develops a black, hairy tongue after taking metronidazole. This is an example of which of the following?

Accepted Answer

A toxic side effect.

Question 9

Which of the following mechanisms is NOT a common way bacteria acquire resistance to antimicrobial drugs?

Accepted Answer

Direct uptake of human DNA.

Question 10

Beta-lactamase (penicillinase) confers resistance to penicillin by which mechanism?

Accepted Answer

It breaks the beta-lactam ring of penicillin, inactivating the drug.

Question 11

Which of the following best describes synergism in antimicrobial therapy?

Accepted Answer

One drug enhances the effect of a second drug.

Question 12

Why might a physician avoid prescribing the antimicrobial with the largest zone of inhibition in a Kirby-Bauer test?

Accepted Answer

Because the drug may not be effective in vivo due to pharmacokinetics or toxicity.

Question 13

Which of the following is a strategy to retard the development of antimicrobial resistance?

Accepted Answer

Using antimicrobials only when necessary and in combination when appropriate.

Question 14

A hospital-acquired bacterial strain is resistant to at least three different classes of antibiotics. This strain is best described as:

Accepted Answer

A multiple-drug-resistant pathogen.

Question 15

Which of the following is a real-world example of cross resistance?

Accepted Answer

A bacterium resistant to all beta-lactam antibiotics due to beta-lactamase production.

Question 16

Which of the following is NOT a mechanism by which bacteria resist the effects of antimicrobial drugs?

Accepted Answer

Increasing uptake of the drug into the cell.

Question 17

A new antiviral drug is developed that prevents viral uncoating. Which stage of the viral life cycle does this drug target?

Accepted Answer

Release of viral nucleic acid inside the host cell.

Question 18

Which of the following best describes the concept of the therapeutic window?

Accepted Answer

The range of concentrations of a drug that are effective without being excessively toxic.

Question 19

A patient develops a secondary infection after broad-spectrum antibiotic therapy. What is the most likely explanation?

Accepted Answer

The antibiotic disrupted normal microbiota, allowing opportunistic pathogens to grow.

Question 20

Which of the following is a reason why drugs that inhibit cell wall synthesis are selectively toxic to bacteria?

Accepted Answer

Bacterial cell walls contain peptidoglycan, which is not found in human cells.

Controlling Microbial Growth in the Body: Antimicrobial Drugs

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