Incidence and Outcomes of Bacterial Bloodstream Infections during Acute Graft-versus-Host Disease Involving the Gastrointestinal Tract after Hematopoietic Cell Transplantation

Epidemiology, Microbiology, and Risk Factors of Bacterial Bloodstream Infections in Patients After Allogeneic Hematopoietic Stem Cell Transplantation

Purpose

To investigate the clinical characteristics, etiology, and risk factors of bacterial bloodstream infection (BSI) in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. This study also aimed to provide a clinical basis for early identification of high-risk patients and optimization of empirical antimicrobial treatment.

Patients and Methods

This is a retrospective study of clinical data during agranulocytosis from 331 patients with hematological malignancies who underwent allo-HSCT at our institute between January 2016 and December 2022. The incidence, distribution and drug resistance patterns, and the risk factors of BSI were analyzed.

Results

Among the 331 HSCT patients, 250 had febrile neutropenia and 45 cases were found to have BSI. The incidence of BSI in patients with agranulocytosis fever was 18% (45/250). A total of 48 pathogens were isolated during BSI episodes, gram-negative bacteria (GNB) accounted for 70.8% (34/48), gram-positive bacteria (GPB) for 29.2% (14/48). Multivariate analysis revealed that ≥grade 2 acute graft-versus-host disease (aGVHD) and previous BSI within 6 months before HSCT were independently associated with an increased occurrence of BSI. Coagulase-negative staphylococci (CoNS) and Escherichia coli were the most commonly isolated GPB and GNB, respectively. A total of 32 GNB were tested for drug susceptibility, the detection rate of carbapenem-resistant Enterobacteriaceae (CRE) was 12.5% (4/32), and extended-spectrum β-lactamase (ESBL) accounted for 56.3% (18/32).

Conclusion

BSIs are still a common and severe complication after allo-HSCT. In our center, BSIs in allo-HSCT patients are dominated by gram-negative bacteria and the resistance rate to carbapenem drugs is high. Risk factors for BSI during agranulocytosis were previous BSI within 6 months before HSCT and ≥grade 2 aGVHD.

Steroid sensitive acute GVHD, but not steroid dependent or steroid resistant, results in similar infection risk as no GVHD following allogeneic hematopoietic cell transplantation

Patients with acute GVHD (aGVHD) have an increased risk for infectious complications after allogeneic hematopoietic cell transplantation (HCT), but the risk according to response to therapy is not well studied. We performed a retrospective analysis of the infectious complications for 1 year following allogeneic HCT at the University of Minnesota for 1143 pediatric and adult patients with and without aGVHD. Patients with aGVHD were classified into treatment response groups based on response to corticosteroids as first-line therapy: steroid sensitive (SS, n=114), steroid resistant (SR, n=103) and steroid dependent (SD, n=168) aGVHD. We observed that the cumulative incidence and density of infections for patients with SS aGVHD parallels those having no GVHD. Infection density (the number of infections that occurred per 100 days at risk) was greater for aGVHD than patients with no GVHD over both early and later post-transplant periods. For GVHD patients, among the infections developed from onset of aGVHD through 80 days of treatment, and until 1-year following transplantation, SS and SD patients had fewer bacterial and viral infections than SR patients. The overlap of non-relapse mortality between SS and SD GVHD patients is a function of SD GVHD being responsive to steroid therapy, even if continued therapy is required. In summary, while valid goals may include reducing unneeded antibacterial antibiotic therapy and preserving microbiome diversity, these data suggest that anti-infective therapy is justified by the density of infections observed during active GVHD treatment.

Impact of HLA disparity on the risk of overall mortality in patients with grade II-IV acute GVHD on behalf of the HLA Working Group of Japan Society for Hematopoietic Cell Transplantation

Acute graft-versus-host disease (aGVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT). Stem cell source or HLA disparity may exert a significant impact on the overall survival (OS) after the development of aGVHD. In order to clarify this point, we performed a retrospective analysis using a database of the Japan Society for HCT. We analyzed the clinical outcomes of 10,035 patients who developed grade II-IV aGVHD. The median age of the patients was 48 years. The probability of 2-year OS after the onset of grade II-IV aGVHD in the study cohort was 54.1%. The multivariate analysis showed that the HLA ≥2-loci mismatched related donor and HLA 1-locus mismatched unrelated donor were significantly associated with an inferior OS after grade II-IV aGVHD. In a subgroup analysis, peripheral blood stem cells and HLA disparity were associated with an inferior OS in patients who received related or unrelated HCT. Thus, the clinical outcome after grade II-IV aGVHD significantly varied as per the combination of the presence of HLA disparity and stem cell source. Further research using other databases is necessary to confirm our findings.

American Society of Transplantation and Cellular Therapy Series, 1: Enterobacterales Infection Prevention and Management after Hematopoietic Cell Transplantation

The Practice Guidelines Committee of the American Society of Transplantation and Cellular Therapy partnered with its Transplant Infectious Disease Special Interest Group to update its 2009 compendium-style infectious diseases guidelines for hematopoietic cell transplantation (HCT). A completely fresh approach was taken, with the goal of better serving clinical providers by publishing each stand-alone topic in the infectious diseases series in a concise format of frequently asked questions (FAQs), tables, and figures [1]. Adult and pediatric infectious diseases and HCT content experts developed and then answered FAQs, and then finalized topics with harmonized recommendations that were made by assigning a strength of recommendation ranging from A to E paired with a level of supporting evidence graded I to III. The first topic in the series focuses on potentially life-threatening infections in HCT caused by Enterobacterales, relevant infection risk factors, and practical considerations regarding prevention and treatment of these infections in the setting of emerging multidrug resistance.

The role of the intestinal microbiota in allogeneic HCT: clinical associations and preclinical mechanisms

Allogeneic hematopoietic cell transplantation (allo-HCT) is a curative-intent therapy for patients with hematological malignancies, but despite advances in the field in recent years, there is still a significant risk of post-transplant mortality. In addition to relapse of the underlying malignancy, the key contributors to this high mortality are graft-versus-host disease (GVHD) and infection. The intestinal microbiota is the collective term describing the community of bacteria, fungi, viruses and protozoa that resides in the human gastrointestinal tract. Bacterial communities have been studied most comprehensively, and disruption of these communities has been associated with the development of a variety of medical conditions in large clinical associative studies. Preclinical studies suggest a mechanistic role for the intestinal microbiota in the instruction and maintenance of both intestinal and systemic immune cell function. This review outlines our current understanding of the relationship between gut bacteria and allo-HCT outcomes, including infection, immune reconstitution, GVHD and relapse, drawing on evidence from both clinical associative studies and preclinical mechanistic studies.