1798. Phenotypic and Genotypic Impact of Antibiotic Stewardship Intervention on Daptomycin-nonsusceptible Enterococcus faecium (DNSE) Clinical Isolates
Session: Poster Abstract Session: Antimicrobial Stewardship: Impact of New Diagnostics
Saturday, October 6, 2018
Room: S Poster Hall
Posters
  • DNSE ASP 2018-3.pdf (422.8 kB)
  • Background:

    Since its introduction in 2009, use of daptomycin for treatment of enterococcal infections has resulted in the emergence of DNSE. Between 2009-2013, daptomycin non-susceptibility among E. faecium was closely associated with emergence of a unique and dominant clone ST736 in our institution. In 2014, we instituted targeted measures to optimize the use of daptomycin. In this study we describe the significant phenotypic and genotypic impact of reduced daptomycin use on clinical enterococcal isolates.

    Methods:

    Enterococcal clinical isolates were recovered from January 2014 through December 2017. Daptomycin susceptibility was determined by MicroScan WalkAway™ System and confirmed by E-test. Selected DNSE and vancomycin-resistant E. faecium (VREfm) clinical isolates were analyzed by next-generation sequencing (NGS) using the Illumina systems to provide multilocus sequencing type (MLST). Daptomycin utilization data was extracted from pharmacy records.

    Results:

    Targeted antibiotic stewardship initiatives consisted of pre-approval, daily review for optimization of dose and duration, rapid de-escalation, consideration for appropriate alternative antibiotics for select disease syndromes and stopping of inappropriate daptomycin therapy. Over 4 years, this lead to a 39% reduction in overall use of daptomycin. Besides direct cost saving, this reduced use was associated with significant reduction in daptomycin non-susceptibility from 12% to 4%, lowering of MIC90 from 8 to 4 μg/ml, and a clonal shift from dominant ST736 to ST117.

    Daptomycin usage

    Days of therapy

    /1000 days

    (monthly average)

    Phenotypic changes

    Genotypic changes

    MIC50

    (μg/ml)

    MIC90

    (μg/ml)

    % DNSE

    Dominant genotype among VREfm

    2014

    742

    4

    8

    12

    ST736 (38%),

    ST18 (21%),

    ST412 (12%),

    ST117 (11%)

    2015

    633

    4

    6

    10

    2016

    576

    4

    4

    7

    2017

    455

    4

    4

    4

    ST736 (5%),

    ST18 (4%),

    ST412 (11%),

    ST117 (41%)

    Conclusion:

    A targeted antibiotic stewardship initiative to address rising rate of daptomycin non-susceptibility among E. faecium, resulted in significant phenotypic and genotypic changes among clinical isolates. This study also shows successful integration of NGS in a clinical microbiology lab to validate phenotypic changes of daptomycin non-susceptibility and to help design future infection control and antibiotic stewardship endeavors.

    Abhay Dhand, MD1, Leslie Lee, PharmD2, Nicholas Feola, PharmD2, Donald Chen, MD3, Nevenka Dimitrova, PhD4, Changhong Yin, MD5, Weihua Huang, PhD5, John Fallon, MD6 and Guiqing Wang, MD, PhD6, (1)Medicine, Westchester Medical Center/New York Medical College, Valhalla, NY, (2)Pharmacy, Westchester Medical Center, Valhalla, NY, (3)Infection Prevention and Control, Westchester Medical Center, Valhalla, NY, (4)Philips Research North America, Cambridge, MA, (5)Pathology, New York Medical College, Valhalla, NY, (6)Pathology, Westchester Medical Center/New York Medical College, Valhalla, NY

    Disclosures:

    A. Dhand, Merck: Speaker's Bureau , Speaker honorarium . Astellas: Scientific Advisor , Consulting fee .

    L. Lee, None

    N. Feola, None

    D. Chen, None

    N. Dimitrova, None

    C. Yin, None

    W. Huang, None

    J. Fallon, None

    G. Wang, None

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