Question 1

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

Accepted Answer

The drug targets the pathogen without causing significant damage to the host.

Question 2

A patient develops severe diarrhea after taking a broad-spectrum antibiotic. Which of the following best explains this phenomenon?

Accepted Answer

A superinfection occurred due to the overgrowth of resistant normal microbiota.

Question 3

Which of the following antibiotics is produced by Streptomyces griseus and is known to cause auditory damage as a side effect?

Accepted Answer

Streptomycin

Question 4

Which of the following drugs inhibits bacterial cell wall synthesis by preventing the cross-linking of peptidoglycans?

Accepted Answer

Penicillin

Question 5

A patient with a urinary tract infection is prescribed nitrofurantoin. What is the primary mechanism of action of this drug?

Accepted Answer

Inhibits protein synthesis by attacking bacterial ribosomal proteins

Question 6

Which of the following best explains why penicillin G must be injected rather than taken orally?

Accepted Answer

It is inactivated by stomach acid.

Question 7

Which of the following is a mechanism by which bacteria can develop resistance to antibiotics?

Accepted Answer

Enzymatic destruction of the drug

Question 8

A combination of trimethoprim and sulfamethoxazole (TMP-SMZ) is used to treat certain infections. What is the advantage of this combination?

Accepted Answer

It provides drug synergism, increasing efficacy.

Question 9

Which of the following antifungal drugs is most commonly used to treat oral thrush and works by binding to ergosterol in fungal membranes?

Accepted Answer

Nystatin

Question 10

A patient is diagnosed with MRSA (methicillin-resistant Staphylococcus aureus). Which antibiotic is most appropriate for treatment?

Accepted Answer

Vancomycin

Question 11

Which of the following statements about tetracyclines is correct?

Accepted Answer

They interfere with tRNA attachment to the ribosome.

Question 12

Which of the following is a common side effect of amphotericin B, a polyene antifungal drug?

Accepted Answer

Kidney toxicity

Question 13

Which of the following best describes the action of sulfonamides?

Accepted Answer

They inhibit the synthesis of folic acid by competing with PABA.

Question 14

A patient is prescribed ciprofloxacin for a urinary tract infection. What is the mechanism of action of this drug?

Accepted Answer

Inhibits DNA topoisomerase

Question 15

Which of the following is a reason why antibiotic misuse can lead to increased resistance?

Accepted Answer

It selects for resistant mutants in the microbial population.

Question 16

Which of the following drugs is used to treat tuberculosis by inhibiting mycolic acid synthesis in mycobacteria?

Accepted Answer

Isoniazid

Question 17

Which of the following best explains why a combination of amoxicillin and clavulanic acid is more effective than amoxicillin alone?

Accepted Answer

Clavulanic acid inhibits penicillinase, protecting amoxicillin from degradation.

Question 18

Which of the following is a mechanism by which antiviral drugs such as acyclovir inhibit viral replication?

Accepted Answer

They act as nucleoside analogs, blocking DNA synthesis.

Question 19

Which of the following is a correct statement about the therapeutic index of an antimicrobial drug?

Accepted Answer

A high therapeutic index indicates a greater margin of safety.

Question 20

Which of the following is a polypeptide antibiotic used topically against gram-positive bacteria?

Accepted Answer

Bacitracin

Antimicrobial Drugs: Mechanisms, Spectrum, and Resistance

Study Guide - Practice Questions