Impact of reappraisal of fluoroquinolone minimum inhibitory concentration susceptibility breakpoints in gram-negative bloodstream isolates

Stephanie C. Shealy, Matthew M. Brigmon, Julie Ann Justo, P. Brandon Bookstaver, Joseph Kohn, Majdi N. Al-Hasan

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The Clinical Laboratory Standards Institute lowered the fluoroquinolone minimum inhibitory concentration (MIC) susceptibility breakpoints for Enterobacteriaceae and glucose non-fermenting Gram-negative bacilli in January 2019. This retrospective cohort study describes the impact of this reappraisal on ciprofloxacin susceptibility overall and in patients with risk factors for antimicrobial resistance. Gram-negative bloodstream isolates collected from hospitalized adults at Prisma Health-Midlands hospitals in South Carolina, USA, from January 2010 to December 2014 were included. Matched pairs mean difference (MD) with 95% confidence intervals (CI) were calculated to examine the change in ciprofloxacin susceptibility after MIC breakpoint reappraisal. Susceptibility of Enterobacteriaceae to ciprofloxacin declined by 5.2% (95% CI: −6.6, −3.8; p < 0.001) after reappraisal. The largest impact was demonstrated among Pseudomonas aeruginosa bloodstream isolates (MD −7.8, 95% CI: −14.6, −1.1; p = 0.02) despite more conservative revision in ciprofloxacin MIC breakpoints. Among antimicrobial resistance risk factors, fluoroquinolone exposure within the previous 90 days was associated with the largest change in ciprofloxacin susceptibility (MD −9.3, 95% CI: −16.1, −2.6; p = 0.007). Reappraisal of fluoroquinolone MIC breakpoints has a variable impact on the susceptibility of bloodstream isolates by microbiology and patient population. Healthcare systems should be vigilant to systematically adopt this updated recommendation in order to optimize antimicrobial therapy in patients with bloodstream and other serious infections.

Original languageEnglish (US)
Article number189
JournalAntibiotics
Volume9
Issue number4
DOIs
StatePublished - Apr 2020

Keywords

  • Bacteremia
  • Chemotherapeutics
  • Ciprofloxacin
  • Escherichia coli
  • Non-fermenters/Pseudomonas aeruginosa
  • Sepsis

ASJC Scopus subject areas

  • General Pharmacology, Toxicology and Pharmaceutics
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)
  • Biochemistry
  • Microbiology

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