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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. Which mechanism of antibiotic resistance involves bacterial enzymes that chemically modify aminoglycosides?

    Answer: Enzymatic inactivation

    Aminoglycoside-modifying enzymes (acetyltransferases, phosphotransferases, nucleotidyltransferases) chemically alter the drug, reducing its binding to the ribosome.

  2. A patient with a severe penicillin allergy (anaphylaxis) needs treatment for a group A streptococcal infection. The best alternative is:

    Answer: Clindamycin

    Clindamycin is a safe alternative for group A streptococcal infections in patients with a history of severe penicillin allergy (anaphylaxis).

  3. Which PK/PD parameter best correlates with the efficacy of beta-lactam antibiotics?

    Answer: Time above MIC (%T>MIC)

    Beta-lactams exhibit time-dependent killing; efficacy is best predicted by the percentage of the dosing interval that free drug concentrations remain above the MIC.

  4. Extended-infusion (3–4 hour) beta-lactam administration is used primarily to optimize which PK/PD target?

    Answer: T>MIC

    Extended infusions increase the time free drug remains above MIC, optimizing the time-dependent killing characteristic of beta-lactams.

  5. A patient is diagnosed with VRE (vancomycin-resistant Enterococcus). Which antibiotic is approved for treating VRE infections?

    Answer: Linezolid

    Linezolid (an oxazolidinone) is FDA-approved for treatment of VRE faecium infections and is active regardless of vancomycin resistance.

  6. Prozone phenomenon in antimicrobial susceptibility testing refers to:

    Answer: Paradoxical growth of bacteria at high antibiotic concentrations (Eagle effect)

    The Eagle effect (paradoxical or prozone effect) is paradoxical growth of bacteria at high antibiotic concentrations, classically described with beta-lactams against streptococci.

  7. Which antibiotic class is associated with causing QT interval prolongation and is contraindicated with other QT-prolonging drugs?

    Answer: Fluoroquinolones

    Fluoroquinolones (especially moxifloxacin) prolong the QT interval via hERG potassium channel blockade, risking torsades de pointes.