1057. A Retrospective Review of Treatment Appropriateness and Outcomes of Enterobacteriaceae (with Inducible ampC β-lactamase) Bacteremias at a Large Academic Medical Centre: Opportunities and Implications for Antimicrobial Stewardship.
Session: Poster Abstract Session: Clinical Infectious Diseases: Bacteremia and Endocarditis
Friday, October 28, 2016
Room: Poster Hall
  • PPC Poster FINAL Jan 22, 2016 ecl rev2.pdf (958.7 kB)
  • Background: Infections caused by ampC carrying Enterobacteriaceae can be problematic. β-lactamase production in these organisms can be inducible upon exposure to β-lactams and lead to treatment failure. Choice of antimicrobial therapy is important, as delay in appropriate empiric therapy is associated with mortality, while avoiding unneeded broad-spectrum antimicrobials is an important component of antimicrobial stewardship. There is little data to support the current practice of carbapenems as first-line agents to treat ampC Enterobacteriaceae infections, and a recent study showed cefepime to be as effective as carbapenems. We aimed to study treatment appropriateness and outcomes for ampC Enterobacteriaceae, and explore outcomes for carbapenem-sparing agents. Methods: Microbiology reports identified 49 patients with bacteremia caused by ampC carrying Enterobacteriaceae over 2 years at a large academic medical centre. Appropriateness of empiric and definitive therapy was assessed by 2 independent reviewers. Demographics, comorbidities, microbiology, and antibiogram data was also collected. Clinical outcomes included all-cause mortality, length of stay, and microbiological cure. Results: Only 12% of Enterobacteriaceae bacteremias presented with derepression of the ampC gene upon first culture. Empiric therapy was appropriate (active based on sensitivity) in 78% of patients. For empiric therapy, most received piperacillin-tazobactam [P/T] (61%), while few (8%) received a carbapenem. Definitive therapy was often a fluoroquinolone [FQN] (63%); the rest received a carbapenem (10%), sulfamethoxazole-trimethoprim [SMX-TMP] (8%), or P/T (8%). Five patients (10%) had bacteremia persisting >1 day. In patients with appropriate definitive therapy, clinical outcomes were not different (carbapenem vs non-carbapenem). Conclusion: The majority of patients studied received an appropriate non-carbapenem as definitive therapy with good microbiological and clinical outcomes. The majority of patients also received appropriate empiric therapy. We suggest that non-β-lactams, especially SMX-TMP, should be explored as carbapenem-sparing options for ampC carrying Enterobacteriaceae which represent a large proportion of gram negative infections. Future work should focus on confirming clinical outcomes in a broader sample.
    Jason Yung, BMSc, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada, Elizabeth Leung, PharmD, BCPS AQ-ID, St. Michael's Hospital, Toronto, ON, Canada, Linda Taggart, MD, MPH, FRCPC, Infectious Diseases/Antimicrobial Stewardship, St. Michaels Hospital, Toronto, ON, Canada and Aaron Campigotto, MD, Microbiology, St. Michaels Hospital, Toronto, ON, Canada


    J. Yung, None

    E. Leung, None

    L. Taggart, None

    A. Campigotto, None

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