178. Evaluation of Oral Antibiotic Stepdown Therapy for the Management of Gram-Negative Rod Bacteremia in a Tertiary Care Medical Center

BACKGROUND: Treatment strategies surrounding bacteremia are constantly changing as new data emerges. Transition from intravenous (IV) to oral (PO) antibiotics in patients with Gram-negative rod bloodstream infections (GNR BSI) remains controversial. The objective of this study was to characterize clinical outcomes in patients who received early (≤72 hours) vs. late (>72 hours) stepdown therapy (ES vs. LS, respectively) for GNR BSIs. METHODS: A single-center, retrospective cohort study was conducted including adults with GNR BSIs admitted to a 610-bed tertiary care academic medical center between January 1, 2016 and December 31, 2017 who were transitioned from IV to PO antibiotics. Patients with severe renal impairment, inadequate source control, prolonged antibiotic course, HIV/AIDS, and pregnancy were excluded. The primary endpoint was clinical failure and secondary endpoints were 30- and 90-day all-cause mortality, duration of bacteremia, and adverse events. RESULTS: 164 patients (ES = 61; NS = 103) were included. Population median age was 63 years, 56% were male, and 19% were immunocompromised. Genitourinary source was most common (48.7%), while the most common organism isolated was Escherichia coli (52.4%). Most infections were community-acquired (70.1%) and the most common step-down therapy choice was ciprofloxacin in 75% of patients. There were no major differences in baseline demographic and clinical characteristics between groups except for the greater presence of central venous catheters (16.4% vs. 35.9%; P = 0.006) in the LS group. Overall clinical failure was 9.8% vs. 13.6% between the ES and LS groups, respectively. The LS group had a higher rate of clinical failure defined by escalation from PO to IV antibiotics (1.6% vs. 10.7%; P = 0.03). Patients who failed therapy tended to be immunocompromised and/or have an intra-abdominal source of infection. Secondary endpoints did not differ between groups. CONCLUSION: Higher clinical failure rates in the LS group indicate that these patients may have underlying clinical characteristics not amenable to stepdown therapy. Choice of step-down therapy was not driven by the source of infection or patient acuity. Further analysis and studies are needed to determine optimal time and population for stepdown. DISCLOSURES: All authors: No reported disclosures.