1022. Is it Time to Re-Evaluate Oral Β-Lactam Antibiotics for Step-Down Therapy of Uncomplicated Gram-Negative Bacteremia?

BACKGROUND: Bloodstream infections (BSI) due to Enterobacteriaceae often require empiric intravenous (IV) antibiotics. Oral antibiotics for the definitive treatment of these infections have been reserved to antibiotics with “high” oral bioavailability, mainly fluoroquinolones (FQ). Safety concerns and increasing resistance associated with FQ has modified clinical practice to identify alternative oral therapies. Select β-lactam (BL) antibiotics are well-tolerated, have moderately high bioavailability, and possess in-vitro activity against Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Proteus mirabilis (P. mirabilis). Limited evidence exists for oral BL step-down therapy for definitive treatment of BSI due to these organisms. METHODS: This retrospective cohort study compares clinical outcomes of patients treated with oral BL antibiotics to those who received oral FQ or trimethoprim/sulfamethoxazole (TS) for the treatment of BSI due to E. coli, K. pneumoniae, and P. mirabilis. The primary outcome is a composite of 30-day all-cause mortality, 30-day readmission due to recurrence, and/or change in oral antibiotic therapy. Secondary endpoints include 90-day development of Clostridium difficile infection, 90-day all-cause readmission, hospital length of stay (LOS), and 90-day recovery of a multi-drug-resistant organism. RESULTS: Nine hundred eighty-one patients were screened and 397 adult patients were included. Excluded patients: IV only (n = 291), polymicrobial blood culture (n = 112), immunocompromised (n = 61), other (n = 120). Two-hundred patients received oral step-down therapy with a BL, and 197 with either an FQ or TS. E. coli was the causative organism for most patients in both groups, and urinary tract was the most common source of BSI. The median total duration of therapy was 14 days in both groups. There was no significant difference in the primary composite endpoint (7% vs. 5.6%, P = 0.561). There was no mortality or differences in secondary outcomes, except LOS (6 vs. 5 days, P = 0.043). CONCLUSION: Utilization of oral BL for the step-down therapy of uncomplicated BSI due to E. coli, K. pneumoniae, and P. mirabilis did not result in worse outcomes compared with those receiving oral FQ or TS. DISCLOSURES: All authors: No reported disclosures.