Clinical Characteristics, Microbiology, and Risk Factors for Mortality of Pre-Engraftment and Post-Engraftment Bloodstream Infection in Hematopoietic Stem Cell Transplantation Recipients

Epidemiology of bloodstream infections and the impact of antimicrobial resistance in pediatric hematopoietic cell transplant

Bloodstream infections (BSI) pose a substantial threat to the well-being and survival of patients undergoing hematopoietic stem cell transplantation (HSCT). Risk factors for these infections vary across the different post-HSCT phases. In the pre-engraftment period, patients are particularly susceptible to infection due to prolonged neutropenia, mucosal damage, and extensive use of central venous line (CVL). In the post-engraftment phase, the emergence of graft versus host diseases further compounds the risk. The epidemiology of these infections has undergone notable changes over the years due to multifactorial reasons, including the evolution of protocols that intensify immunosuppression. In this context, the emergence of multi-drug resistance (MDR) microorganisms can be a challenge due to the elevated risk of mortality in these vulnerable patients. Unfortunately, there is a lack of comprehensive data on this topic, particularly in pediatrics. This article aims to provide a summary of the epidemiology of BSI in the different post-transplant phases and the impact of MDR pathogens. Having knowledge about the local epidemiology of BSI can be instrumental in tailoring targeted therapies, leading to improved survival rates in HSCT recipients.

Microbiology and Clinical Outcome of Bloodstream Infections in Patients After Hematopoietic Stem Cell Transplantation

Purpose

Patients after hematopoietic stem cell transplantation (HSCT) are often followed by bloodstream infections (BSIs). BSI is an important cause of non-relapse mortality (NRM) in HSCT patients.

Methods

We conducted a retrospective cohort study of patients (aged >14 years) who underwent HSCT at our hospital from 2017 to 2021. Population characteristics, BSI microbiology, resistance to common antibiotics, and 30-day all-cause mortality were analyzed.

Results

Of 3054 patients, 169 (5.5%) had BSIs after HSCT. Male, not in complete remission at transplantation and longer duration of neutropenia were risk factors for the development of BSI after HSCT. These BSIs were Gram-negative bacterial (n=123, 69.49%), Gram-positive bacterial (n=27, 15.25%), fungal (n=11, 6.36%), and polymicrobial (n=16, 9.25%). Among the Gram-negative bacteria, the proportions of isolates resistant to ceftazidime, cefepime, and piperacillin-tazobactam were similar (72.93%, 74.80%, and 77.42%, respectively). The overall drug resistance rates of amikacin and imipenem were 16.13% and 43.90%, respectively. Staphylococcus isolates were methicillin-resistant. In Enterococcus isolates, the penicillin resistance rate was 84.62%. Eleven isolates of Candida tropicalis were resistant to fluconazole and were sensitive to amphotericin B and flucytosine. The 30-day all-cause mortality rate of the 169 patients with BSIs was 8.88%. The 30-day all-cause mortality of patients with Gram-negative bacterial BSIs was 7.32%, 25.00% for polymicrobial BSIs, and 36.36% for fungal BSIs. The 30-day all-cause mortality of patients with fungal BSIs was significantly higher than that of patients with Gram-negative (P=0.0023) and Gram-positive bacteria (P=0.0023). Fungal BSI and non-Hodgkin's lymphoma (NHL) were associated with higher 30-day mortality.

Conclusion

Our study reveals the microbiological characteristics and 30-day all-cause mortality in patients with bloodstream infections after HSCT. Our data provides strong support for empirical antimicrobial therapy and infection prevention strategies for patients with BSIs after HSCT.