Pharmacology Antimicrobial and Chemotherapeutic Agents 2 — Questions and Answers
Question 1: Which aminoglycoside antibiotic is most commonly associated with nephrotoxicity and ototoxicity?
- Azithromycin
- Gentamicin (Correct answer)
- Doxycycline
- Clindamycin
Correct answer: Gentamicin
Gentamicin and other aminoglycosides accumulate in renal proximal tubule cells and cochlear hair cells, causing nephrotoxicity and ototoxicity.
Question 2: A patient with a penicillin allergy requires treatment for MRSA bacteremia. Which antibiotic is the drug of choice?
- Nafcillin
- Vancomycin (Correct answer)
- Ampicillin
- Oxacillin
Correct answer: Vancomycin
Vancomycin is the first-line agent for MRSA infections and is a safe alternative for penicillin-allergic patients since it belongs to a different drug class.
Question 3: Which mechanism best explains how fluoroquinolones kill bacteria?
- Inhibition of cell wall synthesis
- Inhibition of DNA gyrase and topoisomerase IV (Correct answer)
- Disruption of cell membrane integrity
- Inhibition of 50S ribosomal subunit
Correct answer: Inhibition of DNA gyrase and topoisomerase IV
Fluoroquinolones inhibit DNA gyrase (topoisomerase II) in gram-negative bacteria and topoisomerase IV in gram-positive bacteria, preventing DNA replication and repair.
Question 4: A nurse is administering IV vancomycin too rapidly. The patient develops flushing, erythema, and hypotension of the face, neck, and torso. This reaction is best described as:
- Anaphylaxis
- Red Man Syndrome (Correct answer)
- Stevens-Johnson Syndrome
- Serum sickness
Correct answer: Red Man Syndrome
Red Man Syndrome is a rate-related infusion reaction caused by non-immune mast cell degranulation and histamine release when vancomycin is infused too rapidly.
Question 5: Which antifungal drug works by inhibiting ergosterol synthesis through blockade of lanosterol 14-alpha-demethylase?
- Amphotericin B
- Nystatin
- Fluconazole (Correct answer)
- Caspofungin
Correct answer: Fluconazole
Azole antifungals like fluconazole inhibit CYP450-dependent lanosterol 14-alpha-demethylase, blocking ergosterol synthesis and disrupting fungal membrane integrity.
Question 6: Metronidazole is the drug of choice for which of the following infections?
- Candida albicans vaginitis
- Clostridioides difficile colitis (Correct answer)
- Streptococcal pharyngitis
- Community-acquired pneumonia
Correct answer: Clostridioides difficile colitis
Metronidazole is first-line therapy for mild-to-moderate C. difficile infection and acts by forming toxic free radicals that damage anaerobic bacterial DNA.
Question 7: Which beta-lactam antibiotic has the broadest spectrum of activity and is most resistant to beta-lactamases?
- Penicillin G
- Amoxicillin
- Imipenem (Correct answer)
- Cephalexin
Correct answer: Imipenem
Imipenem (a carbapenem) has the broadest spectrum among beta-lactams, covering gram-positive, gram-negative, and anaerobic organisms, and resists most beta-lactamases.
Pharmacology Antimicrobial and Chemotherapeutic Agents 2
Which aminoglycoside antibiotic is most commonly associated with nephrotoxicity and ototoxicity?