196. Does Cefepime Provide an Advantage over Ceftriaxone in the Treatment of Bloodstream Infections due to Escherichia coli, Klebsiella pneumoniae group, Klebsiella oxytoca, and Proteus spp. if CTX-M is not Detected by Rapid Molecular Testing?

Abstract Background The BIOFIRE® Blood Culture Identification 2 (BCID2) Panel (bioMérieux) allows for rapid detection of pathogens and antibiotic resistance genes in bloodstream infections (BSIs), including CTX-M, an Extended Spectrum Beta-Lactamase. Atrium Health’s treatment algorithm recommends cefepime (FEP) over ceftriaxone (CRO) for BSI due to non-CTX-M Escherichia coli, Klebsiella pneumoniae group, Klebsiella oxytoca, or Proteus spp. in critically ill patients. It is unclear if use of FEP improves outcomes over CRO in this setting. Methods This was a multisite, retrospective cohort study of adults with BSI due to E. coli, K. pneumoniae group, K. oxytoca, and Proteus spp. without CTX-M detected by BCID2 from April 4, 2022 – February 12, 2023. The primary outcome was a composite of in-hospital mortality and length of stay (LOS) more than 14 days in patients who received FEP vs CRO. Secondary outcomes included in-hospital mortality, hospital LOS, intensive care unit (ICU) LOS, rates of mechanical ventilation, and rates of CRO and FEP resistance. Results Three hundred patients were enrolled: 150 in each group. Patients in the FEP group were more severely ill at baseline by ICU status and PITT bacteremia score and were less likely to have a urinary source of BSI (Table 1). The composite primary outcome of in-hospital mortality or extended LOS occurred in 54/150 (36%) in the FEP group vs 24/150 (16%) in the CRO group; (p < 0.001). In-hospital mortality, hospital LOS, rates of mechanical ventilation and CRO resistance were higher in the FEP 5/158 (3%) vs. 2/150 (1%) in the CRO group. ICU LOS, in-hospital mortality and rates of FEP resistance were similar (Figures 1 and 2). Of note, of the 7/308 isolates with CRO resistance there was no in-hospital mortality or extended LOS in the CRO group and 5/7 were Proteus spp. There was no FEP resistance.Table 1.Select Baseline Characteristics Conclusion Though CRO resistance was relatively low, it was most common among Proteus spp. Treatment with FEP was not associated with improved clinical or microbiological outcomes overall compared to CRO. These results highlight potential overuse of FEP in BSIs due to E.coli, K. pneumoniae group, or K. oxytoca and may have implications on the selection of empiric therapy. Disclosures All Authors: No reported disclosures