Infectious complications after hematopoietic stem cell transplantation: current status and future perspectives in Korea

Cho, Sung-Yeon; Lee, Hyeon-Jeong; Lee, Dong-Gun

In the late 2000s, 26% of E. coli and K. pneumoniae bacteremia isolates from neutropenic patients were ES-BL-producing strains in a single-center study [26] . The incidence of infections caused by carbapenem-resistant Enterobacteriaceae (CRE), along with ESBL-producing Enterobacteriaceae, is increasing in hematologic malignancy patients [18, [28] [29] [30] [31] . K. pneumoniae, E. coli, P. aeruginosa, and Acinetobacter baumannii are clinically important strains associated with the acquisition of carbapenem resistance. A study of prior colonization by CRE as a risk factor for CRE bloodstream infections found that 45% of neutropenic patients with carbapenem-resistant K. pneumoniae rectal colonization experienced bloodstream infection by an identical strain [30] . There is no multicenter study of CRE in HSCT recipients. However, a single-center, retrospective cohort study performed in Korea reported that the incidence of carbapenem-resistant A. baumannii bacteremia was 0.53 cases per 10,000 patient-days; post-engraftment infection by this organism can be fatal [31] . The rate of methicillin-resistant coagulase-negative staphylococci is reportedly higher than 50% in most centers, while the incidence rate of Staphylococcus aureus in HSCT patients is low with a high methicillin-resistance rate of median 56% (range, 18% to 100%) [18] . In the late 2000s, coagulase-negative staphylococci were reported to have a methicillin resistance rate of more than 90% and S. aureus a rate of more than 60% [22] . The incidence of Enterococcus bloodstream infections was 1.76 cases per 1,000 patient-days, with vancomycin-resistant Enterococcus (VRE) accounting for 20.6% [22, 32] . Most VRE bloodstream infections are caused by E. faecium and are associated with long-term hospitalization and an underlying medical condition, but the resistance itself has not been associated with mortality [32] .