2770. Investigating the Impact of Non-CTX-M Producing ESBL-E Bloodstream Infections on Patient Outcomes

BACKGROUND: Studies investigating optimal treatment and patient outcomes for extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) generally do not distinguish between ESBL genes in bloodstream infections (BSI). To address a key knowledge gap, we compare the clinical outcomes of patients with non-CTX-M and CTX-M-producing ESBL-E BSIs. METHODS: We collected 500 ceftriaxone-resistant Enterobacterales bloodstream isolates from patients in the Johns Hopkins Health System between 2018-2021. Broth microdilution confirmed antimicrobial susceptibilities, and whole genome sequencing identified ESBL genes. We used 1:3 propensity score matching (PSM) to compare the odds of 30-day mortality between patients infected with non-CTX-M and CTX-M ESBL-Es. Propensity scores were derived using seven variables: age, sex, severe immune compromise, Pitt bacteremia score ≥4, Charlson comorbidity index ≥5, adequate source control, and carbapenem use. RESULTS: ESBL genes were confirmed in 396 isolates, including 370 (93%) bla(CTX-M) genes and 26 (7%) non-bla(CTX-M) ESBL genes: bla(SHV) (13), bla(OXY) (8), bla(VEB) (5). Common species harboring bla(CTX-M) were: Escherichia coli (265), Klebsiella pneumoniae (88), K. oxytoca (5), and Enterobacter cloacae (5); and non-bla(CTX-M) were: K. pneumoniae (8), K. oxytoca (8), and Proteus mirabilis (5). After PSM, baseline patient characteristics were similar, and the aOR of 30-day mortality was 0.94 (95% CI 0.89-0.99) comparing patients with non-bla(CTX-M) and bla(CTX-M) isolates. In an exploratory analysis limited to patients with non-bla(CTX-M) isolates: 2 of 15 patients (13%) receiving meropenem and 6 of 11 (55%) not receiving meropenem died within 30 days (aOR=0.61; 95% CI 0.42-0.90). CONCLUSION: Mortality was slightly lower in patients with BSIs due to non-CTX-M-producing ESBL-Es compared to CTX-M-producing ESBL-Es. Similar to what has been observed with CTX-M-producing ESBL-Es, meropenem is protective against mortality in patients infected with non-CTX-M producing ESBL-Es, underscoring the importance of diagnostics to detect a comprehensive array of ESBL genes among diverse Enterobacterales. DISCLOSURES: Patricia J. Simner, PhD, Affinity Biosensors: Grant/Research Support|BD Diagnostics: Advisor/Consultant|BD Diagnostics: Grant/Research Support|Entasis: Advisor/Consultant|GeneCapture: Stocks/Bonds|Merck: Advisor/Consultant|OpGen Inc: Board Member|OpGen Inc: Grant/Research Support|OpGen Inc: Honoraria|Qiagen Sciences Inc: Advisor/Consultant|Qiagen Sciences Inc: Grant/Research Support|Shionogi Inc: Advisor/Consultant|T2 Biosystems: Grant/Research Support Sara E. Cosgrove, MD, MS, Debiopharm: Advisor/Consultant|Duke Clinical Research Institute: Advisor/Consultant