Carbapenem versus Cefepime or Piperacillin-Tazobactam for Empiric Treatment of Bacteremia Due to Extended-Spectrum-β-Lactamase-Producing Escherichia coli in Patients with Hematologic Malignancy.

Infections with extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli are common in patients with hematologic malignancy. The utility of cefepime and piperacillin-tazobactam as empiric therapy for ESBL-producing E. coli bacteremia in patients with hematologic malignancy is largely unknown. We conducted a single-center, retrospective cohort review of 103 adult inpatients with leukemia and/or hematopoietic stem cell transplant (HCT) recipients with monomicrobial ESBL-producing E. coli bacteremia. No association between increased 14-day mortality and empiric treatment with cefepime (8%) or piperacillin-tazobactam (0%) relative to that with carbapenems (19%) was observed ( P  = 0.19 and P  = 0.04, respectively). This observation was consistent in multivariate Cox proportional hazards models adjusted for confounding and an inverse probability of treatment-weighted (IPTW) Cox proportional hazards model. Both fever and persistent bacteremia were more common in patients treated empirically with cefepime or piperacillin-tazobactam. Empiric treatment with cefepime or piperacillin-tazobactam did not result in increased mortality relative to that with treatment with carbapenems in patients with hematologic malignancy and ESBL-producing E. coli bacteremia, although most patients were changed to carbapenems early in treatment. However, due to prolonged fever and persistent bacteremia, their role may be limited in this patient population.