Shifting trends in bloodstream infection-causing microorganisms and their clinical impact in patients with haematologic malignancies in South Korea: A propensity score-matched study

Abstract

Background: This study aimed to identify recent trends in the epidemiology of bloodstream infection (BSI)-causing microorganisms among patients with haematologic malignancies (HMs) between 2011 to 2021, and to determine their impact on patient outcomes. Methods: This retrospective study included 6792 patients with HMs, of whom 1308 (19.3%) developed BSI within 1 year of diagnosis. The incidence of BSI-causing microorganisms was determined, and a propensity score-matched study was performed to identify risk factors for 28-day all-cause mortality (ACM) in patients with HM. Results: A total of 6792 patients with HMs were enrolled. The cumulative incidence of BSI and neutropenia was significantly higher in the acute myeloid leukaemia and acute lymphoblastic leukaemia groups compared to other groups, and neutropenia and type of HMs were risk factors for the development of BSI. The annual incidence of coagulase-negative staphylococci (CoNS)-BSI decreased significantly (p<0.001), whereas Klebsiella pneumoniae-BSI increased (p=0.01). Carbapenem nonsusceptibility rates in K. pneumoniae isolates increased from 0.0% to 76.5% (p<0.001). BSI caused by K. pneumoniae [adjusted odds ratio (aOR) 2.17; 95% confidence interval (CI) 1.12–4.21] was associated with higher 28-day ACM compared to that caused by CoNS (aOR 0.86; 95% CI 0.48–1.55). Conclusion: The pathogenic spectrum of BSI-causing bacteria in patients with HMs gradually shifted from gram-positive to gram-negative, especially from CoNS to K. pneumoniae. Considering that K. pneumoniae-BSI had a significantly higher 28-day mortality rate than CoNS-BSI, this evolving trend could adversely impact clinical outcomes of patients with HMs.