P-2264. Epidemiology and Outcomes of Bacteremia in Neutropenic Patients: A Changing Scenario over Time

Abstract Background The epidemiology of bacteremia (B) in neutropenic patients (NP) may differ according to the geographic region or country and can change over time. The growing rate of multidrug-resistant gram-negative bacilli (MDR-GNB) is usually associated with higher mortality. Methods Prospective multicenter study. All the first episodes of B in adult NP with hematologic malignancies were included in 9 centers in Argentina, from May 2014 to December 2023. They were divided in three periods: May 2014-June 2017 (P1), July 2017-June 2020 (P2), and July 2020-December 2023 (P3). Epidemiological, clinical and treatment characteristics, as well as 30-day infection-related mortality of B episodes were compared among the periods. Results One thousand three hundred thirty B episodes were included (P1=411, P2=513, and P3=406). Most patients presented high-risk neutropenia (P1=88.3% vs. P2=90.4% vs. P3=90.3%, p=0.50). Septic shock at presentation was P1=21.9% vs. P2=14.8% vs. P3=21.3%, p=0.008. GNB was the leading cause of B, especially in the third period (63.4% vs. 65.5% vs. 79.6%, p< 0.0001). E. coli, Klebsiella spp., and P. aeruginosa were the most prevalent microorganisms, with no differences among the periods. MDR-GNB were more frequent in P1 and P3 compared with P2: 31.6% vs. 31.7% vs. 25.6%, p=0.02. Resistance mechanisms in P1 vs. P2 vs. P3 were as follows: extended-spectrum beta-lactamase production, 26.3% vs. 19.9% vs. 23.5%, p=0.18; KPC production, 7.7% vs. 9.5% vs. 5%, p=0.07; OXA-48 production, 1.5% vs. 0% vs. 1.9%, p=0.05, and MBL production, 0% vs. 0.9% vs. 7.1%, p< 0.0001. Appropriated antibiotic therapy (AT) was higher in P2 and P3 compared with P1: 85.4% vs. 86.1% vs.78.1%, p=0.002. Thirty-day infection-related mortality was P1=16% vs. P2=6.4% vs. P3=9.6%, p< 0.0001. Conclusion Both GNB and MDR-GNB were the leading cause of B, with a significant increase in the last three years. A change in carbapenemase type has been observed, with a significant rise in MBL, which presents limited therapeutic options. Notwithstanding that, an improvement in the appropriated AT provided and lower infection-related mortality have been observed in the last few years. In order to better adapt AT and improve the outcome in NP, changes in B local epidemiology must be known. Disclosures Diego Torres, Medical Doctor, Gador: Honoraria|GSK: Advisor/Consultant|Khight Therapeutics: Honoraria|MSD: Honoraria Lucas Tula, Medical Doctor, MSD: Advisor/Consultant|MSD: Honoraria|Takeda Pharmaceuticals: Advisor/Consultant Alberto Carena, n/a, Roche Diagnostics: Latin America Medical Lead for Roche Diagnostics