Question 1

Which of the following best describes the principle of selective toxicity in antimicrobial drugs?

Accepted Answer

Drugs should be more toxic to the pathogen than to the host.

Question 2

Why are there many antibacterial drugs but fewer antifungal and antiviral drugs?

Accepted Answer

Bacterial cells have more differences from human cells, providing more drug targets.

Question 3

Which mechanism of action is used by beta-lactam antibiotics such as penicillin?

Accepted Answer

Inhibition of cell wall synthesis

Question 4

A patient is prescribed miconazole for a yeast infection. What is the primary target of this drug?

Accepted Answer

Fungal ergosterol synthesis

Question 5

Which of the following drugs inhibits folic acid synthesis, thereby blocking nucleotide synthesis in bacteria?

Accepted Answer

Sulfonamide

Question 6

What is the main difference between prokaryotic and eukaryotic ribosomes that allows selective toxicity of certain antibiotics?

Accepted Answer

Prokaryotic ribosomes are 70S (30S & 50S), eukaryotic ribosomes are 80S (40S & 60S).

Question 7

Which of the following is a disadvantage of broad-spectrum antimicrobial drugs?

Accepted Answer

They can lead to opportunistic (secondary) infections due to loss of microbial antagonism.

Question 8

Acyclovir is used to treat infections caused by which type of pathogen, and what is its mechanism of action?

Accepted Answer

Viruses; inhibits DNA synthesis

Question 9

Which of the following best explains why sulfonamides are selectively toxic to bacteria but not humans?

Accepted Answer

Bacteria synthesize folic acid, while humans obtain it from their diet.

Question 10

Which of the following drugs acts by inhibiting the attachment or entry of viruses into host cells?

Accepted Answer

T20 (for HIV)

Question 11

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

Accepted Answer

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

Question 12

Which of the following is NOT a mechanism of action for antimicrobial drugs?

Accepted Answer

Enhancement of host cell metabolism

Question 13

Which class of drugs is most likely to cause toxicity in humans due to similarities between fungal and human cell membranes?

Accepted Answer

Azoles

Question 14

Which of the following equations represents the composition of prokaryotic ribosomes targeted by antibiotics such as streptomycin?

Accepted Answer

$$70S = 30S + 50S$$

Question 15

Which of the following drugs is a base analog that inhibits RNA synthesis in viruses such as respiratory syncytial virus (RSV)?

Accepted Answer

Ribavirin

Question 16

A chemotherapeutic drug is defined as:

Accepted Answer

A drug that acts against diseases.

Question 17

Which of the following is a disadvantage of narrow-spectrum antimicrobial drugs?

Accepted Answer

They have fewer applications due to limited range of activity.

Question 18

Which of the following best describes the action of penicillins and cephalosporins?

Accepted Answer

They bind enzymes that form cross bridges between NAMs, resulting in a weak cell wall and cell lysis.

Question 19

Which of the following scenarios best illustrates the concept of microbial antagonism?

Accepted Answer

Resident microbiota compete with potential pathogens for space and nutrients, preventing infection.

Question 20

Which of the following drugs is most likely to be used to treat herpes simplex virus (HSV) infections by inhibiting DNA synthesis?

Accepted Answer

Acyclovir

Controlling Microbial Growth in the Body: Antimicrobial Drugs (Lecture 9, Part I)

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