Which pair of definitions correctly describes synergism and antagonism in the context of antibiotic combinations?

You are given MICs for two antibiotics: Drug A inhibits step 1 of a biosynthetic pathway (MIC = 8 µg/mL alone) and Drug B inhibits step 2 (MIC = 4 µg/mL alone). In combination, inhibitory concentrations are 2 µg/mL for A and 1 µg/mL for B. Calculate the fractional inhibitory concentration (FIC) index and interpret whether the interaction is synergistic, additive/indifferent, or antagonistic.

Which statement accurately differentiates bacteriostatic and bactericidal antibiotics and explains a common mechanism for antagonism between them?

A new beta-lactam antibiotic increases the intracellular concentration of Drug Z (an antibiotic that targets an intracellular enzyme). Which experimental observation would best support the hypothesis that the beta-lactam enhances uptake to produce synergy?

A synergistic combination reduces the necessary dose of Drug A by 4-fold while maintaining clinical efficacy. Which clinical consideration should most strongly influence whether to adopt this combination as standard therapy?