Impaired function of hematopoiesis after treatment with chimeric antigen T‐cells (CAR‐T) is a frequent finding and can interest a wide range of patients, regardless of age and underlying disease. Trilinear cytopenias, as well as hypogammaglobulinemia, B‐cell aplasia, and T‐cell impairment, can severely affect the infectious risk of CAR‐T recipients, as well as their quality of life. In this review, we provide an overview of defects in hematopoiesis after CAR‐T, starting with a summary of different definitions and thresholds. We then move to summarize the main pathogenetic mechanisms of cytopenias, and we offer insight into cytomorphological aspects, the role of clonal hematopoiesis, and the risk of secondary myeloid malignancies. Subsequently, we expose the major findings and reports on T‐cell and B‐cell quantitative and functional impairment after CAR‐T. Finally, we provide an overview of current recommendations and leading experiences regarding the management of cytopenias and defective B‐ and T‐cell function.

Microbiota changes during allogeneic hematopoietic stem cell transplantation has several known causes: conditioning chemotherapy and radiation, broad-spectrum antibiotic administration, modification in nutrition status and diet, and graft-versus-host disease. This article aims to review the current knowledge about the close link between microbiota and allogeneic stem cell transplantation setting. The PubMed search engine was used to perform this review. We analyzed data on microbiota dysbiosis related to the above-mentioned affecting factors. We also looked at treatments aimed at modifying gut dysbiosis and applications of fecal microbiota transplantation in the allogeneic stem cell transplant field, with particular interest in fecal microbiota transplantation for graft-versus-host disease (GvHD), multidrug-resistant and clostridium difficile infections, and microbiota restoration after chemotherapy and antibiotic therapy.

Background: Bloodstream infections affect up to 20% of pediatric cancer patients receiving intensive care, contributing significantly to morbidity and mortality, with infection-related mortality rates reported to be as high as 16%. Methods: The identification of microorganisms directly from whole blood is difficult due to several factors, such as interference from host genomic material, low bacterial load, the endogenous components of whole blood and exogenous substances, which can interfere with the identification process. Nevertheless, rapid microbial diagnosis remains of paramount importance in these patients. Results and Conclusion: Here, we present the first case of bacterial pathogen identification directly from whole blood using MALDI-TOF mass spectrometry in an onco-hematological pediatric patient affected by sepsis and admitted to Bambino Gesù Children’s Hospital (IRCCS) in Rome, Italy.