1831. Clinical Outcomes of Patients with Bacteremia Due to Extended-Spectrum Beta-Lactamase (ESBL)-Producing Enterobacteriaceae (EB) Treated with Carbapenem (Cbp), Standard Intermittent Piperacillin-Tazobactam (SI-PTZ) or Extended Infusion Piperacillin-Tazobactam (EI-PTZ)
Session: Poster Abstract Session: Treatment of HAIs/Antimicrobial Resistant Infections
Saturday, October 10, 2015
Room: Poster Hall
Background: Infections due to ESBL-EB have emerged as a significant cause of morbidity and mortality as antibiotic choices for effective treatment remain minimal.  Currently, Cbps are considered the treatment of choice for serious ESBL-EB infections.  Increased use of Cbps raises concerns for added selective pressure and continued emergence of carbapenem-resistant EB.  Studies on PTZ dosing strategies, particularly extended infusion regimens, suggest maximizing pharmacodynamic target attainment in the treatment of gram-negative infections results in improved outcomes.  The objective of this study was to compare the clinical outcomes of patients with bacteremia caused by ESBL-EB treated with Cbp, SI-PTZ or EI-PTZ as empiric and definitive therapy.

Methods: This was a single-center, retrospective cohort study.  Adult patients with EBSL-EB bacteremia with E. coli, Klebsiella species, or Proteus mirabilis that were sensitive in vitro to Cbps and PTZ were included.  Isolates were presumed to be an ESBL-producing organism if they had a ceftriaxone MIC>1 as per 2010 CLSI recommendations.  The 3 treatment exposure arms (Cbp, SI-PTZ, and EI-PTZ) were compared in 2 cohorts: empiric therapy cohort (ET) and definitive therapy cohort (DT).  The primary outcome measure was mortality.  A multivariable logistic regression analysis was conducted to control for confounding variables.

Results: There were 40 patients in the ET (Cbp, 14; EI-PTZ, 14; SI-PTZ, 14) and 43 patients in the DT (Cbp, 28; EI-PTZ, 8; SI-PTZ, 7).  Pitt bacteremia score was associated with increased mortality in both the ET (unadjusted odds ratio [OR], 2.30; 95% confidence interval [CI], 1.21-4.38) and DT (unadjusted OR, 2.25, 95% CI, 1.2-4.21) but was not statistically significant on multivariable analysis.  In the DT, EI-PTZ was associated with a higher risk of mortality in the unadjusted analysis (unadjusted OR, 7.8, 95% CI, 1.03-59.33).  On multivariable analysis, risk of mortality was not increased for EI-PTZ in both the ET (adjusted OR, 0.81, 95% CI, 0.03-23.86) and the DT (adjusted OR, 1.56, 95% CI, 0.08-29.69).

Conclusion: Antibiotic therapy with PTZ was not associated with a higher risk of mortality in comparison to Cbp therapy in patients with ESBL-EB bacteremia.

Navaneeth Narayanan, PharmD, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, Tanaya Bhowmick, MD, Medicine, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ, Randy Jackson, Medical Student, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ, John Lough, MD, Department of Medicine, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ and Melvin Weinstein, MD, Medicine and Pathology, Rutgers-Robert Wood Johnson Medical School, New Brunswick, NJ

Disclosures:

N. Narayanan, None

T. Bhowmick, None

R. Jackson, None

J. Lough, None

M. Weinstein, None

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