Q: Which of the following equations best represents the therapeutic index of a drug?

$$\text{Therapeutic Index} = \frac{\text{Dose tolerated}}{\text{Effective dose}}$$

Question 1

Which of the following best describes the mechanism of action of beta-lactam antibiotics?

Accepted Answer

They prevent cross-linkage of NAM subunits in bacterial cell walls by binding to enzymes responsible for this process.

Question 2

A patient is prescribed a drug that selectively binds to isoleucyl-tRNA synthetase, preventing the loading of isoleucine onto tRNA molecules. Which of the following best describes the effect of this drug?

Accepted Answer

It interferes with protein synthesis by preventing the proper charging of tRNA molecules.

Question 3

Which of the following drugs would be most effective against a fungal infection by targeting the synthesis of glucan in the cell wall?

Accepted Answer

Echinocandins

Question 4

A hospital patient develops a secondary infection after broad-spectrum antibiotics eliminate much of their normal flora. What is the term for this phenomenon?

Accepted Answer

Superinfection

Question 5

Which of the following statements about selective toxicity is correct?

Accepted Answer

Selective toxicity is achieved when a drug targets features unique to the pathogen, leaving host cells unharmed.

Question 6

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

Accepted Answer

Direct uptake of drugs from the environment

Question 7

A drug is found to inhibit prokaryotic DNA gyrase. Which class of antimicrobial agents does this drug most likely belong to?

Accepted Answer

Quinolones and fluoroquinolones

Question 8

Which of the following is a plausible reason why polymyxin is not commonly used to treat infections in humans?

Accepted Answer

It is toxic to human kidneys.

Question 9

A patient with HIV is prescribed a drug that inhibits reverse transcriptase. Why does this drug not harm human cells?

Accepted Answer

Human cells lack reverse transcriptase.

Question 10

Which of the following equations best represents the therapeutic index of a drug?

Accepted Answer

$$	ext{Therapeutic Index} = \frac{	ext{Dose tolerated}}{	ext{Effective dose}}$$

Question 11

Which of the following is a mechanism by which Mycobacterium tuberculosis resists fluoroquinolone drugs?

Accepted Answer

It produces MfpA protein that binds DNA gyrase, preventing drug binding.

Question 12

A patient is given a combination of two drugs, and the effect is greater than the sum of their individual effects. What is this phenomenon called?

Accepted Answer

Synergism

Question 13

Which of the following best explains why broad-spectrum antibiotics can lead to superinfections?

Accepted Answer

They kill normal flora, reducing microbial antagonism and allowing opportunistic pathogens to proliferate.

Question 14

Which of the following drugs would be most appropriate for treating a mycobacterial infection by disrupting mycolic acid formation?

Accepted Answer

Isoniazid

Question 15

A new antimicrobial drug is found to block viral attachment to host cells. Which of the following best describes its mechanism?

Accepted Answer

It is an attachment antagonist.

Question 16

Which of the following is a plausible consequence of using second and third generation drugs?

Accepted Answer

They are new variations developed to overcome resistance and improve efficacy.

Question 17

Which of the following tests is used to determine the minimum concentration of an antimicrobial agent required to inhibit the growth of a microorganism?

Accepted Answer

Minimum inhibitory concentration (MIC) test

Question 18

A patient is prescribed an oral antimicrobial agent. Which of the following is a potential disadvantage of this route of administration compared to intravenous delivery?

Accepted Answer

Oral drugs may be less readily absorbed and distributed to infected tissues.

Question 19

Which of the following best describes the action of trimethoprim?

Accepted Answer

It interferes with nucleotide synthesis, acting as a metabolic antagonist.

Question 20

A bacterial pathogen is found to be resistant to three different antimicrobial agents. What is the term for this type of resistance?

Accepted Answer

Multiple drug resistance

Chapter 10 Notes

Study Guide - Practice Questions

Study Guide - Flashcards