1917. Clinical Outcomes of Patients Receiving Fluoroquinolones to Treat Bacteremia Caused by Enterobacteriaceae Isolates Considered Intermediate or Resistant to These Agents According to the Recently Revised Susceptibility Testing Standards by the Clinical and Laboratory Standards Institute (CLSI).
Session: Poster Abstract Session: Clinical: Bacteremia and Endocarditis
Saturday, October 7, 2017
Room: Poster Hall CD
  • 1917_IDWPOSTER.pdf (503.8 kB)
  • Background: The Clinical and Laboratory Standards Institute (CLSI) recently lowered minimum inhibitory concentration (MIC) ciprofloxacin (CIP) and levofloxacin (LEV) breakpoints for Enterobacteriaceae. These revisions are based on pharmacokinetic-pharmacodynamic attainment analyses, which may not accurately predict clinical outcomes for all infections. We evaluated the clinical outcomes of patients receiving CIP or LEV for the treatment of bacteremia caused by Enterobacteriaceae isolates considered intermediate or resistant to these agents according to the newly revised CLSI breakpoints but susceptible by the old ones.

    Methods: Retrospective study of adult patients with bacteremia caused by Enterobacteriaceae isolates with CIP MIC values of 0.5 and 1 mcg/mL who were treated with CIP or LEV for at least three days between January 2014 and December 2016. Patients on prophylactic fluoroquinolones (FQs) were excluded. Descriptive statistics were used to summarize baseline demographic characteristics and clinical outcomes.

    Results: Forty six episodes of Enterobacteriaceae bacteremia were identified. Median age was 63.5 years (interquartile range [IQR], 27.5). Median Charlson comorbidity index was 6 (IQR, 3). Median quick Sepsis Organ Failure Assessment score was 1 (IQR, 1). Urinary tract infections were the most common cause of bacteremia (52.2%) and Klebsiella species were the most commonly isolated Enterobacteriaceae (45.7%). Median duration of FQ therapy was 11.5 days (IQR, 5.5). The recommended doses of CIP and LEV were used in 30.6% of cases. Median length of stay (LOS) was 5 days (IQR, 5). Most (78.3%) patients were discharged home. Thirty-day recurrence, re-admission, and mortality rates were 0, 21.7, and 4.3%, respectively. The LOS for bacteremia from a urinary source was three days shorter than the LOS for bacteremia from other sources (p = 0.037). Fifty percent of re-admissions were due to non-infectious complaints.

    Conclusion: Despite suboptimal FQ dosing, the clinical outcomes of the patients in this study are similar to those of patients in previous studies of Enterobacteriaceae bacteremia. This suggests that the recently revised CLSI MIC breakpoints may underestimate the efficacy of FQs for the treatment of bacteremia and other serious infections caused by Enterobacteriaceae.

    Luis Tulloch, MD1, Elise Martin, MD, MS1, Daniel Z. Uslan, MD, MS, FIDSA, FSHEA1 and Romney Humphries, PhD2, (1)Infectious Diseases, David Geffen School of Medicine/University of California, Los Angeles, Los Angeles, CA, (2)Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA


    L. Tulloch, None

    E. Martin, None

    D. Z. Uslan, None

    R. Humphries, None

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