Question 1

Which scientist is credited with the discovery of penicillin, and what was its source organism?

Accepted Answer

Alexander Fleming; Penicillium

Question 2

What is the primary reason why antibiotics that inhibit cell wall synthesis, such as penicillins, do not harm human cells?

Accepted Answer

Human cells lack peptidoglycan in their cell walls

Question 3

Which genus of bacteria is responsible for producing more than half of all clinically useful antibiotics?

Accepted Answer

Streptomyces

Question 4

A patient develops a Clostridioides difficile infection after broad-spectrum antibiotic therapy. This is an example of:

Accepted Answer

Superinfection

Question 5

Which of the following best describes the mechanism of action of tetracyclines?

Accepted Answer

Interfere with tRNA attachment to the ribosome, inhibiting protein synthesis

Question 6

Why are broad-spectrum antibiotics not always the best choice for treating infections?

Accepted Answer

They can lead to superinfections by killing normal microbiota

Question 7

Which of the following drugs is used specifically to treat infections caused by Mycobacterium tuberculosis?

Accepted Answer

Isoniazid

Question 8

Aminoglycosides, such as streptomycin, exert their antibacterial effect by:

Accepted Answer

Changing the shape of the 30S ribosomal subunit, causing mRNA to be read incorrectly

Question 9

Which of the following is a common mechanism by which bacteria develop resistance to beta-lactam antibiotics?

Accepted Answer

Production of beta-lactamase enzymes

Question 10

Sulfonamides inhibit bacterial growth by interfering with which metabolic pathway?

Accepted Answer

Folic acid synthesis

Question 11

Which of the following statements best explains why sulfa drugs selectively harm bacteria but not human cells?

Accepted Answer

Humans do not synthesize folic acid and must obtain it from their diet

Question 12

Which of the following is a mode of action for antifungal drugs such as amphotericin B?

Accepted Answer

Disruption of ergosterol in the fungal plasma membrane

Question 13

A patient is prescribed a combination of trimethoprim and sulfamethoxazole. This combination is an example of:

Accepted Answer

Synergism

Question 14

Which test is used to determine the minimal inhibitory concentration (MIC) of an antibiotic?

Accepted Answer

E test (Epsilometer test)

Question 15

Which of the following best describes the action of quinolones such as ciprofloxacin?

Accepted Answer

Inhibit DNA gyrase, blocking DNA replication

Question 16

A patient with a viral infection is treated with acyclovir. Why does this drug not harm uninfected human cells?

Accepted Answer

Acyclovir is only activated by viral enzymes present in infected cells

Question 17

Which of the following mechanisms is NOT a common way bacteria resist the effects of antibiotics?

Accepted Answer

Increased permeability to the drug

Question 18

Which of the following drugs is used to treat tapeworm infections by preventing ATP generation in the parasite?

Accepted Answer

Niclosamide

Question 19

Why is it difficult to develop chemotherapeutic agents that target viruses without harming host cells?

Accepted Answer

Viruses use many of the host cell’s metabolic pathways

Question 20

Which of the following best describes the effect of using tetracycline and penicillin together in treating a bacterial infection?

Accepted Answer

Antagonism, because tetracycline inhibits bacterial growth, reducing the effectiveness of penicillin

Antimicrobial Drugs: Mechanisms, Classes, and Resistance

Study Guide - Practice Questions