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Antimicrobial Pharmacology Flashcards

7 cards from real MCCQE 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 Pharmacology flashcards as text

  1. A patient with a penicillin allergy requires treatment for a serious Staphylococcus aureus infection. Which antibiotic has the highest risk of cross-reactivity with penicillin?

    Answer: Cefazolin

    First-generation cephalosporins like cefazolin share a similar R1 side chain with some penicillins, conferring the highest cross-reactivity risk among beta-lactams.

  2. Which mechanism best explains why aminoglycosides exhibit concentration-dependent bactericidal activity?

    Answer: Higher peak concentrations drive greater uptake into bacteria via the electron transport chain

    Aminoglycoside uptake into bacterial cells is energy-dependent and increases with higher drug concentrations, producing a concentration-dependent kill curve.

  3. A patient on warfarin develops a urinary tract infection. Which antibiotic choice requires the most careful INR monitoring due to interaction with warfarin metabolism?

    Answer: Trimethoprim-sulfamethoxazole

    Trimethoprim-sulfamethoxazole inhibits CYP2C9, reducing warfarin metabolism and significantly elevating INR, increasing hemorrhage risk.

  4. Daptomycin is contraindicated for the treatment of Staphylococcus aureus pneumonia because:

    Answer: It is inactivated by pulmonary surfactant

    Pulmonary surfactant binds and inactivates daptomycin, rendering it ineffective for lung infections.

  5. Which pharmacokinetic property makes once-daily dosing of aminoglycosides advantageous compared to traditional thrice-daily dosing?

    Answer: The post-antibiotic effect allows bacterial suppression between doses

    Aminoglycosides exhibit a prolonged post-antibiotic effect (PAE), meaning bacterial growth remains suppressed even after drug levels fall below the MIC.

  6. A patient receiving prolonged vancomycin therapy develops sensorineural hearing loss. This toxicity is most likely related to which pharmacokinetic parameter?

    Answer: Renal insufficiency causing drug accumulation and high troughs

    Ototoxicity from vancomycin is most strongly associated with drug accumulation due to renal impairment, leading to persistently elevated trough concentrations.

  7. Which statement accurately describes the mechanism of action of linezolid?

    Answer: It binds the 50S subunit at the peptidyl transferase center, preventing initiation complex formation

    Linezolid binds the 23S rRNA of the 50S subunit, blocking formation of the 70S initiation complex and halting protein synthesis.