$$\mathrm{Penicillin} + \mathrm{\beta\text{-}lactamase} \rightarrow \mathrm{Inactive\ product}$$

Question 1

Which of the following best describes the concept of selective toxicity in antimicrobial therapy?

Accepted Answer

The drug targets microbial cells with minimal harm to host cells.

Question 2

Paul Ehrlich is best known for which of the following contributions to antimicrobial therapy?

Accepted Answer

Development of the first synthetic antimicrobial, Salvarsan, for syphilis.

Question 3

Which of the following is a correct distinction between natural and semi-synthetic penicillins?

Accepted Answer

Semi-synthetic penicillins have a broader spectrum of activity than natural penicillins.

Question 4

A patient is prescribed an antibiotic that inhibits bacterial cell wall synthesis. Which of the following drugs is most likely being used?

Accepted Answer

Penicillin G

Question 5

Which of the following best explains how bacteria can become resistant to β-lactam antibiotics?

Accepted Answer

By producing enzymes that hydrolyze the β-lactam ring

Question 6

Which of the following antibiotics inhibits protein synthesis by binding to the 30S ribosomal subunit?

Accepted Answer

Streptomycin

Question 7

A patient develops a Clostridioides difficile infection after broad-spectrum antibiotic use. This is an example of which adverse effect?

Accepted Answer

Disruption of normal microbiota

Question 8

Which of the following is NOT a mechanism by which bacteria can resist the effects of antibiotics?

Accepted Answer

Increased uptake of the drug

Question 9

Which equation best represents the hydrolysis of the β-lactam ring by β-lactamase?

Accepted Answer

$$\mathrm{Penicillin} + \mathrm{\beta	ext{-}lactamase} ightarrow \mathrm{Inactive\ product}$$

Question 10

Which of the following antibiotics disrupts the bacterial plasma membrane, leading to cell lysis?

Accepted Answer

Polymyxin B

Question 11

A hospital isolates a strain of Staphylococcus aureus that is resistant to methicillin. Which mechanism of resistance is most likely responsible?

Accepted Answer

Production of an altered penicillin-binding protein (PBP2a)

Question 12

Which of the following best describes the difference between bacteriostatic and bactericidal drugs?

Accepted Answer

Bacteriostatic drugs inhibit bacterial growth, while bactericidal drugs kill bacteria.

Question 13

Which of the following is a common consequence of the misuse of antibiotics?

Accepted Answer

Selective advantage for resistant bacteria

Question 14

Which of the following antibiotics inhibits nucleic acid synthesis by targeting DNA gyrase?

Accepted Answer

Ciprofloxacin

Question 15

A patient is treated with an antibiotic that inhibits folic acid synthesis. Which of the following drugs is most likely being used?

Accepted Answer

Sulfonamide

Question 16

Which of the following is a plausible reason why Gram-negative bacteria are often more resistant to antibiotics than Gram-positive bacteria?

Accepted Answer

They possess an outer membrane that restricts drug entry.

Question 17

Which of the following best describes the action of vancomycin?

Accepted Answer

Inhibits cell wall synthesis by binding to the D-Ala-D-Ala terminus of peptidoglycan precursors

Question 18

A bacterial strain acquires a plasmid encoding an efflux pump. Which resistance mechanism does this represent?

Accepted Answer

Decreased accumulation of the drug via active export

Question 19

Which of the following scenarios best illustrates the link between antibiotic misuse and resistance?

Accepted Answer

A patient takes antibiotics for a viral infection, leading to the selection of resistant bacteria.

Question 20

Which of the following equations best represents the inhibition of bacterial protein synthesis by tetracycline?

Accepted Answer

$$\mathrm{Tetracycline} + 30\mathrm{S\ ribosomal\ subunit} \rightarrow \mathrm{Inhibition\ of\ tRNA\ binding}$$

Antimicrobial Medications: Mechanisms, Selection, and Resistance

Study Guide - Practice Questions