Can you compare breakpoint numbers among antibiotics?

• A. Yes
• B. No
• C. Only within same species
• D. Only with culture data

Answer: (B)

Breakpoints are drug- and organism-specific thresholds used to decide if an isolate is susceptible to a particular antibiotic. They are established based on pharmacokinetics and pharmacodynamics, achievable drug concentrations at the infection site, dosing regimens, and expected clinical outcomes. Because different antibiotics have different potencies, tissue penetration, and PK/PD targets, their numeric breakpoints aren’t directly comparable across drugs. A breakpoint value for one antibiotic cannot be interpreted the same way as a breakpoint for another, even within the same organism. You compare an isolate’s MIC to the breakpoint for that specific antibiotic, not across different drugs.