Question 1

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

Accepted Answer

Prevents cross-linking of peptidoglycan in the bacterial cell wall

Question 2

A patient is treated with a broad-spectrum antibiotic and subsequently develops a yeast infection. What is the most likely explanation for this occurrence?

Accepted Answer

The antibiotic suppresses normal microflora, allowing opportunistic yeast to proliferate

Question 3

Which equation represents the chemical change that occurs when penicillin is inactivated by penicillinase?

Accepted Answer

$$\mathrm{Penicillin\ \xrightarrow{Penicillinase}\ Penicilloic\ acid}$$

Question 4

Which of the following drugs is most likely to cause damage to the auditory nerve and kidneys?

Accepted Answer

Gentamycin (an aminoglycoside)

Question 5

Why are cell wall synthesis inhibitors such as penicillins considered to have excellent selective toxicity?

Accepted Answer

They target peptidoglycan, which is only found in bacteria

Question 6

Which of the following best explains why vancomycin is used as a last resort for MRSA infections?

Accepted Answer

MRSA is resistant to most other antibiotics, and vancomycin is effective against it

Question 7

Which of the following mechanisms is NOT a common method of antibiotic resistance?

Accepted Answer

Increased synthesis of peptidoglycan

Question 8

A patient with tuberculosis is treated with a combination of isoniazid and rifampin. What is the primary reason for using combination therapy?

Accepted Answer

To decrease the likelihood of resistance developing

Question 9

Which of the following drugs inhibits the synthesis of essential metabolites by mimicking PABA?

Accepted Answer

Sulfonamides

Question 10

Which of the following statements about tetracyclines is TRUE?

Accepted Answer

They are bacteriostatic and have a broad spectrum of activity

Question 11

Which of the following is a major risk associated with the use of fluoroquinolones in children?

Accepted Answer

Harm to cartilage development

Question 12

Which of the following drugs is used to treat fungal infections by increasing membrane permeability through targeting ergosterol?

Accepted Answer

Amphotericin B

Question 13

Which of the following is the primary target of macrolide antibiotics such as erythromycin?

Accepted Answer

50S ribosomal subunit

Question 14

A patient is prescribed TMP-SMZ for a urinary tract infection. Which pathway is being inhibited?

Accepted Answer

Folic acid synthesis

Question 15

Which of the following statements about antiviral drugs is correct?

Accepted Answer

Nucleoside analogs such as acyclovir block viral DNA replication

Question 16

Which of the following best explains why antifungal agents often have toxicity issues in humans?

Accepted Answer

Fungi and humans are both eukaryotes, making selective toxicity difficult

Question 17

Which of the following drugs is used to treat malaria by interfering with DNA replication?

Accepted Answer

Quinine

Question 18

Which of the following mechanisms allows bacteria to eject antibiotics from the cell, contributing to resistance?

Accepted Answer

Efflux pumps

Question 19

Which of the following is a reason why polymyxin B is only used for topical treatments?

Accepted Answer

It is highly toxic to human cells due to similarity in plasma membrane structure

Question 20

Which of the following best describes the action of chloramphenicol?

Accepted Answer

Binds to the 50S ribosomal subunit and inhibits peptide bond formation

Antimicrobial Drugs: Mechanisms, Classes, and Resistance

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