Question 1

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

Accepted Answer

The drug targets unique features of the pathogen, minimizing harm to the host.

Question 2

Why are there fewer effective drugs against eukaryotic pathogens compared to bacteria?

Accepted Answer

Eukaryotic pathogens share more similarities with human cells, making selective toxicity harder to achieve.

Question 3

Which of the following drugs acts by inhibiting the cross-linking of NAM subunits in bacterial cell walls?

Accepted Answer

Penicillin

Question 4

A patient is prescribed an antibiotic that targets the 30S subunit of the bacterial ribosome. Which of the following is a possible side effect due to this mechanism?

Accepted Answer

Inhibition of mitochondrial protein synthesis in the patient

Question 5

Which of the following best explains why broad-spectrum antibiotics can lead to superinfections?

Accepted Answer

They kill normal flora, reducing microbial antagonism and allowing opportunistic pathogens to thrive.

Question 6

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

Accepted Answer

By spontaneous mutations or acquiring resistance plasmids via transformation, transduction, or conjugation

Question 7

A Kirby-Bauer disk diffusion test is performed. What does a large zone of inhibition around an antibiotic disk indicate?

Accepted Answer

The bacteria are susceptible to the antibiotic.

Question 8

Which of the following drugs disrupts the integrity of fungal cell membranes by binding to ergosterol?

Accepted Answer

Amphotericin B

Question 9

Sulfanilamide acts as a competitive inhibitor of the enzyme that converts PABA to dihydrofolic acid. What is the consequence of this inhibition?

Accepted Answer

Inhibition of DNA and RNA nucleotide biosynthesis

Question 10

Which of the following is a reason why intravenous (IV) administration of an antibiotic achieves higher blood concentrations more rapidly than oral administration?

Accepted Answer

IV administration bypasses absorption barriers and delivers the drug directly into the bloodstream.

Question 11

A bacterial strain produces beta-lactamase. Which of the following antibiotics is this strain most likely resistant to?

Accepted Answer

Penicillin

Question 12

Which of the following is a potential side effect of tetracycline use in children?

Accepted Answer

Formation of calcium complexes that damage teeth and bones

Question 13

Which of the following best describes the action of nucleic acid analogs such as acyclovir?

Accepted Answer

They terminate the synthesis of viral DNA or RNA by mimicking normal nucleotides.

Question 14

Which of the following is NOT a recommended method for retarding the development of antimicrobial resistance?

Accepted Answer

Prescribing antibiotics for viral infections

Question 15

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

Accepted Answer

Increased uptake of the drug into the cell

Question 16

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

Accepted Answer

The antibiotic disrupted the normal bacterial flora, allowing yeast to overgrow.

Question 17

Which of the following is the best definition of the minimum inhibitory concentration (MIC)?

Accepted Answer

The lowest concentration of an antimicrobial agent that prevents visible growth of a microorganism

Question 18

Which of the following is a reason why effective antiviral drugs are rare compared to antibacterial drugs?

Accepted Answer

Viruses have fewer unique targets because they use host cell machinery for replication.

Question 19

Which of the following best explains why semisynthetic derivatives of beta-lactams are advantageous?

Accepted Answer

They are more readily absorbed and have a broader spectrum of activity.

Question 20

A patient is prescribed Tamiflu for influenza. What is the mechanism of action of this drug?

Accepted Answer

It acts as a competitive inhibitor of neuraminidase, preventing the release of new virions.

Controlling Microbial Growth in the Body: Antimicrobial Agents and Resistance

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