Breakpoint to Minimum Inhibitory Concentration Quotient: A Critical Metric for Optimizing Antimicrobial Decision-making

Abstract Antibiotic selection and dosing strategies are fundamentally guided by antibiotic susceptibility, which relies on minimum inhibitory concentration (MIC) values and established clinical breakpoints. Breakpoint to MIC quotient (BMQ) is the ratio of the clinical breakpoint to the MIC of the infecting pathogen and serves as a determinant of the drug’s efficacy margin. A higher BMQ suggests a greater likelihood of treatment success, whereas a lower quotient may indicate borderline efficacy, requiring dose optimization or alternative therapy. This quotient aids in balancing drug selection when various agents exhibit identical susceptibility categorizations but differ in clinical susceptibility breakpoint. BMQ has emerged as a critical parameter in optimizing antimicrobial therapy by integrating pharmacokinetic/pharmacodynamic relationships with bacterial susceptibility profiles. This narrative review aims to explore the concept, significance, challenges, and future prospects of BMQ in guiding antimicrobial therapy.