165. Comparative Effectiveness of Oral Fluoroquinolones vs. β-Lactams for the Treatment of Patients with Enterobacteriaceae Bloodstream Infections

Abstract

Background. Fluoroquinolones (FQ) are associated with unacceptable rates of adverse drug events (ADE) and drug resistance. Safe and effective alternative oral agents are needed for definitive treatment of Enterobacteriaceae bloodstream infections (BSI). This study aims to determine whether treatment failure rates were similar in patients who received FQ or β-lactams (BL) for stepdown treatment of Enterobacteriaceae BSI. Methods. We conducted a retrospective cohort study comparing oral BL vs. FQ as definitive therapy for patients with BSI due to Escherichia coli, Klebsiella spp., or Proteus spp. Eligible patients were ≥18 years old with a monomicrobial BSI treated with a single definitive oral antibiotic. Patients with a total antibiotic treatment duration of <6 or >21 days were excluded. Groups were matched based on age and gender. The primary outcome was treatment failure defined as recurrence or all-cause mortality within 90 days with a 10% non-inferiority margin. Secondary outcomes were death or recurrence within 30 and 90 days, symptomatic urinary tract infection (UTI) or BSI within 30 days, and the safety outcome of antibiotic-related ADE. Results. The average age was 68 years, with 94% males. In the BL group, 80% had a urinary source of infection vs. 69% of the FQ group. The majority of patients had source control (88% of BL group vs. 83% of FQ group). The most common pathogens were E. coli (66%) and K. pneumoniae (24%). Cefpodoxime (71%) and ciprofloxacin (85%) were the most commonly used oral antibiotics. The average duration of oral therapy was 9.2 vs. 9.6 days and total duration was 14.4 vs. 13.9 days in the BL vs. FQ group, respectively. The primary outcome occurred in 15.4% of the BL group vs. 12.3% of the FQ group (P = 0.8002, RR = 0.80, 95% CI = 0.33-1.90). No deaths were directly attributed to infection. Symptomatic UTI or BSI within 30 days occurred in 20% of BL patients vs. 21.5% of FQ patients (P = 1.0000, RR = 1.07, 95% CI = 0.55-2.11). Mortality or recurrence at 30 days were similar between groups (4.6% of BL group vs. 9.2% of FQ group, P = 0.4920, RR = 2.00, 95% CI = 0.52-7.66). One FQ patient experienced an antibiotic-related ADE (C. difficile infection). Conclusion. BL are non-inferior to FQ and appear to be as effective for oral stepdown treatment of Enterobacteriaceae BSI without the associated risks.