Don't Get Wound Up: Revised Fluoroquinolone Breakpoints for Enterobacteriaceae and Pseudomonas aeruginosa

Fluoroquinolones remain some of the more commonly prescribed antimicrobial agents in the United States, despite the wide array of reported side effects that are associated with their use. In 2019, the Clinical and Laboratory Standards Institute revised the fluoroquinolone antimicrobial susceptibility testing breakpoints for both and This breakpoint revision was deemed necessary on the basis of pharmacokinetic and pharmacodynamic analyses suggesting that the previous breakpoints were too high, in addition to the inability of the previous breakpoints to detect low-level resistance to this antibiotic class. In this minireview, we review the published data in support of this revision, as well as the potential challenges that these breakpoint revisions are likely to pose for clinical laboratories.