Background: Enterobacteriaceae  (EB) and non-fermentative bacteria (NFB) are the main pathogens responsible for gram-negative bloodstream infections (GN-BSI) in patients with hematological malignancies (HMs). These two pathogen types have heterogeneous resistance mechanisms to antibiotics. However, the impact of pathogen species and pattern of antibiotic resistance on the outcomes of patients with HMs remains unclear.
Methods: We retrospectively collected clinical data of patients with HMs at three comprehensive hospitals in Hunan Province, China, between January 2010 and May 2018. The data analyzed the impact that different species and patterns of antibiotic resistance had on the outcome of patients with HMs.
Results: The majority of the 835 monomicrobial isolates collected from patients with HMs and GN-BSIs were Enterobacteriaceae  (75.7%). While detections of MDR pathogens in BSIs as a whole are decreasing, sub-analysis shows that detections of extended spectrum β-lactamase-producing (ESBL) Enterobacteriaceae  and carbapenem-resistant pathogens in BISs are rising. Comparing different species, the early mortality rate associated with infections caused by NFB was significantly higher than infections caused by Enterobacteriaceae  (22.6% vs 9.7%, p < 0.001). Across different multidrug-resistant (MDR) patterns, ESBL bacteria did not have a significant impact on health outcomes. Carbapenem-resistant bacteria, on the other hand, were observed to significantly affect early mortality rate, such as carbapenem-resistant Klebsiella pneumoniae  (36.0% vs 7.6%, P < 0.001) and carbapenem-resistant non-fermentative bacteria (44.7% vs 16.5%, P < 0.001).
Conclusion: Our findings suggest that both species and patterns of antibiotic resistance can affect the early mortality of patients with HMs during BSI.
Keywords: multidrug-resistant patterns, hematological malignancies, gram-negative bloodstream infections, carbapenem-resistant bacteria