Etiological Agents of Bacteremia in Patients with Hematological Malignancies: Evaluation of 18 Years of Data.

Objective: Timely initiation of effective empirical antibacterial therapy depends on continuous surveillance of local epidemiology and antimicrobial resistance patterns. This study aimed to evaluate the microbial etiology and antimicrobial susceptibility patterns of bacteremia in patients with hematological malignancies. Materials and Methods: This descriptive study was conducted in a university hospital between 2006 and 2023. We analyzed the distribution of microorganisms causing bacteremia and their antimicrobial susceptibility patterns in patients with hematological malignancies. Data were evaluated in two periods: 2006-2014 and 2015-2023. Results: A total of 2930 bacteremia episodes were recorded. Gram-positive organisms accounted for 60.5%, Gram-negative organisms for 32.3%, and yeasts for 4.0%. The most common Gram-positive pathogens were coagulase-negative staphylococci (CoNS), Conclusion: This 18-year surveillance study demonstrates changing microbiology and resistance patterns of bacteremia in patients with hematological malignancies. Gram-positive organisms, particularly CoNS, remain the most common pathogens, although their incidence is declining. Yeast infections are on the rise, and increasing resistance among Gram-negative organisms, especially to fluoroquinolones, piperacillin-tazobactam, and carbapenems, is concerning. Continuous local surveillance is essential for optimizing empirical treatment strategies and improving patient outcomes.