1037. Effect of Oral Step-Down Therapy on Readmission Rates in Escherichia coli Bacteremia

BACKGROUND: Escherichia coli is the most common cause of community-acquired bloodstream infections. Fluoroquinolones (FQ) and trimethoprim/sulfamethoxazole (TS) are preferred for oral step-down therapy due to high bioavailability. Antimicrobial stewardship programs commonly restrict FQ use, promoting consideration of non-FQ agents for treatment of sensitive organisms. We hypothesized that oral β-lactams would be non-inferior to FQ and TS with a primary outcome of 30-day all-cause readmission. METHODS: This was a retrospective non-inferiority study that reviewed electronic health records for patients with E. coli bacteremia from January 1, 2016 to December 31, 2017. Exclusion criteria included hospital acquired infections, death during hospitalization and concomitant infections. Patient demographics, Pitt Bacteremia Score, Charleston Comorbidity Index, antibiotic regimen (IV/PO), and readmission were collected. Patients were divided into two groups, oral FQ/TS verses β-lactams. A pretrial noninferiority margin for the primary outcome was set at 3%. Secondary outcomes included 30-day infection and E. coli readmission. Significant risk factors for readmission were entered into a multiple logistic regression model in a forward stepwise approach using SPSS. RESULTS: Demographics were similar between groups, 57 patients received FQ/TS and 151 received β-lactams. The 30-day-all cause readmission rate was 15.8% and 29.1%, respectively (absolute risk difference 13.3%, CI: 1–25).β-lactams were found to be inferior to FQ/TS for 30-day all-cause readmission. readmission occurred in 5.3% of patients in the FQ/TS group verses 14.6% of patients in the β-lactam group (P = 0.07). E.coli accounted for 100% of the infection-related readmissions in the FQ/ST group and 70% in the β-lactam group. Patients who received a β-lactam antibiotic were more likely to be readmitted then those patients treated with FQ/TS (odds ratio: 2.25, CI: 0.95–5.30, P = 0.06). CONCLUSION: Step-down therapy to oral β-lactams resulted in higher rates of 30-day all-cause and infection-related readmissions in patients with E. coli bacteremia. DISCLOSURES: All authors: No reported disclosures.