Background The reliability of piperacillin-tazobactam (TZP) and cefepime (FEP) breakpoints for extended spectrum β-lactamase Enterobacterales (ESBL-E) isolates remains controversial. The Infectious Diseases Society of America recommends against the use of TZP and FEP for the treatment of bloodstream infections (BSIs) caused by ESBL-E, even when in-vitro susceptibility is demonstrated. The University of Pennsylvania Health System microbiology laboratory suppresses TZP susceptibilities on Escherichia coli and Klebsiella pneumoniae blood isolates nonsusceptible to ceftriaxone (CRO) or ceftazidime (CAZ) and specifies the presence of a multidrug resistant organism. However, FEP susceptibilities are reported. The objective of this study was to assess appropriate antimicrobial prescribing for the treatment of FEP-susceptible ESBL-E BSIs with our institution’s current susceptibility reporting practices. Methods This multicenter retrospective observational study included patients with blood cultures positive for E. coli, K. oxytoca, K. pneumoniae, and Proteus mirabilis nonsusceptible to CRO or CAZ but susceptible to FEP from August 1, 2018 through August 1, 2021. Patients with a concominant gram-negative infection or true beta-lactam allergy were excluded. Patients were assessed for appropriate therapy (demonstrated susceptibility to and administration of carbapenems fluoroquinolones, novel beta-lactam/beta-lactamase inhibitors, or sulfamethoxazole-trimethoprim) within 24 h following the availability of susceptibility results. Results During the study period 38 patients were included. Of the 38 patients, 52.6% (n=20) received appropriate therapy with an average time to appropriate therapy of 3.7 (SD 2.1) h. Among patients receiving inappropriate therapy (n=18), 50% (n=9) were changed to appropriate therapy >24 h after susceptibility results, with an average time to appropriate therapy of 46.5 (SD 44.4) h. The remaining 9 patients (23.7%) did not receive appropriate therapy beyond 24 h. Conclusion Reporting FEP susceptibility results on ESBL-E blood isolates may contribute to the prescribing of FEP for the treatment of ESBL-E BSIs and delay appropriate antimicrobial therapy. Given these findings, cefepime will now be suppressed on ESBL-E blood isolates. Disclosures All Authors: No reported disclosures.

Background A well-known clinical dilemma complicating the management of infections in people who inject drugs (PWID) is the restriction of outpatient parenteral antimicrobial therapy. As a result, PWID experience prolonged hospitalizations to complete parenteral antimicrobial courses inpatient. This strategy is also associated with increased rates of patient-directed discharge (PDD). Dalbavancin, a long-acting lipoglycopeptide, serves two unique roles in this population: step-down therapy to decrease inpatient length of stay once clinically stable and salvage therapy in the setting of imminent PDD. Methods This retrospective review of PWID from November 2019 through October 2021 identified patients in which on- or off-label dalbavancin could be considered. Day of hypothetical dalbavancin administration was determined when both ≥7 days of therapy and ≥48 hours of clinical stability (non-critical unit, afebrile, resolved leukocytosis, and source control or negative blood cultures) were completed. Included patients had ≥7 days of therapy remaining at time of hypothetical dalbavancin administration. A one-time dalbavancin dose was considered to provide up to 14 days of antimicrobial coverage. Patients were included in either the step-down cohort (completed entire parenteral antimicrobial course inpatient) or salvage therapy cohort (PDD prior to completing course). The number of potentially preventable inpatient days with dalbavancin and readmissions due to infection progression were assessed in each cohort, respectively. Results Nineteen patients were identified as potential dalbavancin candidates. In the step-down cohort (n=11) a one-time dalbavancin dose prevented a maximum of 146 inpatient days. In the salvage cohort (n=8), hypothetical dalbavancin administration at time of PDD could have prevented six readmissions due to infection progression, associated with 36 additional inpatient days. Conclusion Inpatient administration of dalbavancin may bridge treatment disparities experienced by PWID by reducing unnecessary inpatient days for parenteral antibiotic administration and by preventing hospital readmissions attributable to inadequate antimicrobial course. Disclosures All Authors: No reported disclosures.