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
A febrile neutropenic patient with no identified source of infection requires empiric antibiotic therapy. Which regimen is most appropriate?
Answer: Anti-pseudomonal beta-lactam (e.g., piperacillin-tazobactam)
Febrile neutropenia requires empiric antipseudomonal beta-lactam therapy (piperacillin-tazobactam, cefepime, or meropenem) to cover gram-negative pathogens including Pseudomonas.
Which antimicrobial property describes the ability of a drug to reach effective concentrations at the site of infection?
Answer: Tissue penetration
Tissue penetration describes how well an antibiotic reaches the site of infection, which is critical for treating infections in poorly perfused sites like bone or abscesses.
Resistance via outer membrane porin loss primarily affects which class of antibiotics and in which organism?
Answer: Carbapenems in Pseudomonas aeruginosa (OprD loss)
Loss of the OprD outer membrane porin in Pseudomonas aeruginosa reduces uptake of imipenem, conferring resistance to carbapenems.
A patient taking rifampin for tuberculosis is started on oral contraceptives. What counseling is most important?
Answer: Rifampin induces CYP450 enzymes, reducing oral contraceptive effectiveness
Rifampin is a potent CYP450 inducer that accelerates estrogen and progestin metabolism, significantly reducing oral contraceptive plasma levels and efficacy.
Which condition is most likely to require surgical source control in addition to antibiotic therapy?
Answer: Liver abscess
Liver abscesses often require drainage (percutaneous or surgical) in addition to antibiotics because antibiotics alone penetrate poorly into the necrotic abscess core.
Heteroresistance to antibiotics describes a situation where:
Answer: A small subpopulation within an otherwise susceptible strain expresses resistance
Heteroresistance is the coexistence of susceptible and resistant subpopulations within a single strain, which can lead to treatment failure when the resistant subpopulation is selected.
Which antibiotic's efficacy is primarily predicted by its AUC/MIC ratio (concentration-dependent with prolonged PAE)?
Answer: Azithromycin
Azithromycin and other macrolides exhibit AUC/MIC-dependent efficacy with a prolonged post-antibiotic effect, allowing once-daily or even single-dose regimens.