P-923. Aminoglycosides as a Carbapenem-Sparing Strategy for Urinary Tract Infection Caused by Extended-Spectrum Beta-Lactamase Producing Enterobacterales: A Retrospective Comparative Study

Abstract Background The rise of extended spectrum beta-lactamase (ESBL) producing Enterobacterales has led to increased carbapenem (CP), raising concerns for carbapenem resistant Enterobacterales (CRE) and Pseudomonas (CRP), in addition to increasing Clostridium difficile infection (CDI) risk due to gut microbiome disruption. Aminoglycosides (AG) lack these risks and remain a viable treatment (tx) for ESBL producing Enterobacterales. At Olive View-UCLA Medical Center (Sylmar, CA), AGs were deployed as a CP-sparing strategy for ESBL-related urinary tract infection (UTI). The aim of this study was to evaluate the use of AG vs CB for ESBL Enterobacterales UTIs.Figure 1Secondary outcomesClotridioides difficile infection (CDI), acute kidney injury (AKI) Methods This single center retrospective study from 1/2019-5/2023 included adults ≥18 years of age admitted for UTI. All positive urine cultures (Ucx) with ESBL E. coli, Klebsiella, or Proteus spp were reviewed and included if treated with CP or AG for >3 days (d) for either cystitis or pyelonephritis. Primary outcomes were tx success (no recurrent UTI with the same organism within 30d) and symptom resolution by discharge. Secondary outcomes were 30d all-cause mortality, tx discontinuation due to side effect (SE), acute kidney injury (AKI), CDI incidence within 30d, and CRE or CRP infection within 90d. Primary outcomes were compared using one sided z-test for non-inferiority (5% margin) and secondary outcomes with Fisher’s exact test using R (R Core team, 2024). Results Of 540 Ucx reviewed, 81 met criteria (41 AG, 40 CP). The CP group had higher baseline creatinine and more frequent bacteremia. Otherwise, there was no difference in baseline characteristics [Table 1]. AG was non-inferior to CP for treatment success (90.2% vs. 77.5%; difference 12.7%, 95% CI: -0.53% to 26.0%; p = 0.014) and improvement by discharge (97.6% vs. 90.0%; difference 7.6%, 95% CI: -1.19% to 16.3%; p = 0.009). There were no differences in secondary outcomes [Figure1]. One AG case developed CRP. None in either group developed CRE within 90d of therapy or stopped tx due to SE. Conclusion AG were non-inferior and had more favorable outcomes compared to CP for ESBL UTI treatment. Both showed similar safety profiles, with no increased risk of AKI or other side effects. Findings support AG as a viable CP-sparing alternative in ESBL UTIs. Disclosures All Authors: No reported disclosures