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Antimicrobial Therapy Principles Flashcards

7 cards from real Pharmacology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Antimicrobial Therapy Principles flashcards as text

  1. A patient with a creatinine clearance of 15 mL/min requires antibiotic therapy. Which agent requires the most significant dose reduction?

    Answer: Vancomycin

    Vancomycin is primarily renally eliminated and requires substantial dose adjustment (extended intervals or reduced doses) in severe renal impairment.

  2. Bacteriostatic antibiotics are generally preferred over bactericidal agents in which clinical scenario?

    Answer: Mild community-acquired pneumonia in an immunocompetent host

    In immunocompetent patients with mild infections, bacteriostatic antibiotics are sufficient because the host immune system can clear growth-inhibited bacteria.

  3. Which antibiotic is considered the drug of choice for treating Legionella pneumophila pneumonia?

    Answer: Azithromycin

    Azithromycin (or other macrolides/fluoroquinolones) is first-line for Legionella because the organism is an intracellular pathogen and beta-lactams have no efficacy.

  4. Combining a beta-lactam with a beta-lactamase inhibitor (e.g., amoxicillin-clavulanate) expands coverage primarily against which organisms?

    Answer: Beta-lactamase-producing Haemophilus influenzae and anaerobes

    Beta-lactamase inhibitors protect the beta-lactam from hydrolysis, restoring activity against organisms that produce beta-lactamase enzymes.

  5. A patient is treated with trimethoprim-sulfamethoxazole (TMP-SMX). Which nutrient synthesis pathway does this combination block?

    Answer: Folate synthesis

    TMP inhibits dihydrofolate reductase and SMX inhibits dihydropteroate synthase, together blocking sequential steps in folate synthesis.

  6. Which term describes the lowest concentration of antibiotic that prevents visible bacterial growth after 18–24 hours of incubation?

    Answer: Minimum inhibitory concentration (MIC)

    The MIC is the lowest antibiotic concentration that inhibits visible bacterial growth under standardized incubation conditions.

  7. A patient on warfarin starts metronidazole for C. difficile. What is the expected drug interaction?

    Answer: Increased INR due to CYP2C9 inhibition by metronidazole

    Metronidazole inhibits CYP2C9, reducing warfarin metabolism and increasing INR, raising the risk of bleeding.