Clinical-associated characteristics and microbiological features of bloodstream nontyphoidal salmonella infection in adult patients receiving allogeneic hematopoietic stem cell transplantation

Reduction of product composition variability using pooled microbiome ecosystem therapy and consequence in two infectious murine models

Growing evidence demonstrates the key role of the gut microbiota in human health and disease. The recent success of microbiotherapy products to treat recurrent Clostridioides difficile infection has shed light on its potential in conditions associated with gut dysbiosis, such as acute graft-versus-host disease, intestinal bowel diseases, neurodegenerative diseases, or even cancer. However, the difficulty in defining a "good" donor as well as the intrinsic variability of donor-derived products' taxonomic composition limits the translatability and reproducibility of these studies. Thus, the pooling of donors' feces has been proposed to homogenize product composition and achieve higher taxonomic richness and diversity. In this study, we compared the metagenomic profile of pooled products to corresponding single donor-derived products. We demonstrated that pooled products are more homogeneous, diverse, and enriched in beneficial bacteria known to produce anti-inflammatory short chain fatty acids compared to single donor-derived products. We then evaluated pooled products' efficacy compared to corresponding single donor-derived products in Salmonella and C. difficile infectious mouse models. We were able to demonstrate that pooled products decreased pathogenicity by inducing a structural change in the intestinal microbiota composition. Single donor-derived product efficacy was variable, with some products failing to control disease progression. We further performed in vitro growth inhibition assays of two extremely drug-resistant bacteria, Enterococcus faecium vanA and Klebsiella pneumoniae oxa48, supporting the use of pooled microbiotherapies. Altogether, these results demonstrate that the heterogeneity of donor-derived products is corrected by pooled fecal microbiotherapies in several infectious preclinical models.IMPORTANCEGrowing evidence demonstrates the key role of the gut microbiota in human health and disease. Recent Food and Drug Administration approval of fecal microbiotherapy products to treat recurrent Clostridioides difficile infection has shed light on their potential to treat pathological conditions associated with gut dysbiosis. In this study, we combined metagenomic analysis with in vitro and in vivo studies to compare the efficacy of pooled microbiotherapy products to corresponding single donor-derived products. We demonstrate that pooled products are more homogeneous, diverse, and enriched in beneficial bacteria compared to single donor-derived products. We further reveal that pooled products decreased Salmonella and Clostridioides difficile pathogenicity in mice, while single donor-derived product efficacy was variable, with some products failing to control disease progression. Altogether, these findings support the development of pooled microbiotherapies to overcome donor-dependent treatment efficacy.

Risk factors and clinical features for post-transplant thoracic air-leak syndrome in adult patients receiving allogeneic haematopoietic stem cell transplantation

Post-transplant thoracic air-leak syndrome (ALS) is rare but potentially life-threatening in patients receiving allogeneic haematopoietic stem cell transplantation (HSCT). Nevertheless, papers on thoracic ALS are limited, and this complication remains largely unknown. We reviewed 423 adult patients undergoing allogeneic HSCT from 2003 to 2014. Risk factors, clinical features and survival for thoracic ALS were collected and analysed. Thirteen out of 423 patients (3.1%) developed post-transplant thoracic ALS, including two ALS patients in the early phase. The median age at HSCT was 33 years among 13 patients with thoracic ALS. Male patients were predominant (69%). The median onset time was 253 days (range: 40–2680) after HSCT. Multivariate analysis revealed that grade III–IV acute graft-versus-host disease (GVHD) (p = 0.017), extensive chronic GVHD (cGVHD) (p = 0.019) and prior history of pulmonary invasive fungal infection (p = 0.007) were significant risk factors for thoracic ALS. In patients with cGVHD, those with thoracic ALS had a significantly worse survival than those without thoracic ALS (p = 0.04). Currently, published data analysing and exploring post-transplant thoracic ALS are limited. Our study employed a large patient cohort and determined the risk factors and clinical features for post-transplant thoracic ALS.