Etiology, antimicrobial resistance, and outcomes of bloodstream infection in neutropenic hematological patients

Abstract: BACKGROUND: Bloodstream infections (BSIs) cause significant morbidity and mortality in neutropenic patients with hematological malignancies, especially amid rising antimicrobial resistance. Updated local data are essential to guide empirical therapy. OBJECTIVES: The aims of this study were to assessed the etiology, resistance patterns, clinical outcomes of BSIs, and the diagnostic performance of real-time PCR (RT-PCR) versus conventional blood culture. MATERIALS AND METHODS: A prospective observational study was conducted at Azadi Teaching Hospital (September 2024–May 2025) on 109 neutropenic adults. Blood cultures and multiplex RT-PCR were used to identify pathogens and resistance genes. Clinical features, antimicrobial susceptibility, and 30-day outcomes were analyzed. RESULTS: BSIs occurred in 24 patients (22%). Blood culture positivity was low (3.7%), while RT-PCR detected pathogens in 20.2%, increasing diagnostic yield nearly sixfold. Gram-negative bacteria predominated (70.8%), mainly Escherichia coli (37.5%), and Klebsiella pneumoniae (20.8%). ESBL production was universal, and 72.7% of Gram-negative isolates were carbapenem-resistant. Resistance genes included NDM (33.3%), VIM (8.3%), OXA-48 (4.2%), and mecA (12.5%). MDR pathogens caused 54.2% of infections. Appropriate empirical therapy was achieved in 62.5%. Intensive care unit (ICU) admission occurred in 29.1% of BSI cases. Overall mortality was 10.1%, with BSI-related mortality of 29.2%. Carbapenem-resistant infections significantly increased mortality (57.1% vs. 11.1%). Predictors of death included carbapenem resistance, ICU admission, and neutropenia >7 days. CONCLUSIONS: BSIs in neutropenic hematological patients are mostly caused by MDR Gram-negative organisms with high carbapenem resistance. RT-PCR substantially improves diagnostic sensitivity. Updated empirical therapy and stronger antimicrobial stewardship are urgently needed.