Which statement best summarizes why beta-lactam antibiotics are bactericidal?

A clinical isolate expresses a plasmid-encoded beta-lactamase that hydrolyzes the beta-lactam ring. Which modification to therapy directly targets this resistance mechanism?

Pharmacodynamic modeling suggests a bacterial strain inactivates 80% of administered ampicillin molecules by secreted beta-lactamase. If a beta-lactamase inhibitor reduces the enzyme's activity by 90%, what fraction of the original ampicillin remains active? (Assume linear inactivation and start with 100 units of active drug.)

You are treating a biofilm-associated device infection where most bacteria are slow-growing and enclosed in extracellular matrix. Synthesize an optimal antibiotic strategy involving beta-lactams and justify modifications needed to improve efficacy.