210. Step-down from IV to oral therapy in patients with bacteremia due to Enterobacteriaceae: fluoroquinolones (FQ) vs. ß-lactams (BL) or trimethoprim-sulfamethoxazole (TMP-SMX)

BACKGROUND: Patients with Gram-negative bloodstream infection (GN BSI) commonly transition from intravenous (IV) to oral therapy after clinical improvement. Some clinical reports suggest similar outcomes with oral step down to TMP/SMX or BL compared with FQ in uncomplicated GN BSI, despite questionable pharmacodynamic target achievement with oral administration of the former. We sought to compare clinical outcomes in Stanford Health Care (SHC) patients with GN BSI who received step-down therapy with FQ vs. BL or TMP/SMX. METHODS: This was a retrospective cohort study of patients treated at SHC from 1/2010–December 2018 for Enterobacteriaceae bacteremia with oral stepdown to FQ vs. non-FQ (TMP-SMX, BL) initiated by day 7 of therapy. Preliminary data were obtained from electronic health records (EHR) and analyzed via the GreenButton informatics consult service at SHC. The primary outcome was 30-day mortality. Secondary outcomes included 30 and 90-day recurrent BSI, and 90-day C.difficile infection (CDI). Survival analysis was completed for each outcome using the log-rank test to calculate hazard ratio (HR). Cohorts were compared without adjustment and with basic matching controlling for age, sex, length of EHR record, and number of encounters with SHC. RESULTS: Of 529 eligible patients, 414 were in the FQ vs. 115 in the non-FQ oral stepdown cohorts. In unadjusted analysis, 30-day mortality was similar between the FQ and non-FQ groups, (5.8% vs. 6.1%, HR 1.06; 95% CI, 0.46–2.46), P = 0.89. Thirty-day recurrent BSI (1.2% vs. 2.6%, HR 2.20; 95% CI, 0.53–9.20) P = 0.27) and 90-day CDI rates (3.1% vs. 1.7%, HR 0.56; 95% CI 0.13–2.48, P = 0.44) were similar between groups. Ninety-day recurrent BSI was higher in the non-FQ group (1.9% vs. 5.2%, HR 1.38; 95% CI, 0.31–6.15. P = 0.0485).(Table 1) In matched analysis (n = 61), 30-day mortality was similar between groups (5.8% vs. 6.1%; HR 1.06, 95% CI 0.46–2.46, P = 0.89). Matched analysis found no statistically significant differences between groups for all secondary outcomes. (Table 2) CONCLUSION: In this study, 30-day mortality was not different among patients that received oral step down to an FQ vs. non-FQ for the treatment of Enterobacteriaceae bacteremia. Larger, prospective trials are warranted to validate observations and determine optimal dosing of oral antibiotics in this setting. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.