Intestinal Domination and the Risk of Bacteremia in Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation

Bacterial bloodstream infections in the allogeneic hematopoietic cell transplant patient: new considerations for a persistent nemesis

“…136 During HCT, patients experience dramatic alterations in the intestinal microbiota with marked decreases in overall bacterial diversity, increasing risk for aGvHD and BSI. 137 In many instances, a single bacterial taxon can predominate and replace a previously rich and diverse milieu of organisms. 137 Low microbiome diversity and dysbiosis have independently been associated with BSI and transplant-related mortality.…”

“…137 In many instances, a single bacterial taxon can predominate and replace a previously rich and diverse milieu of organisms. 137 Low microbiome diversity and dysbiosis have independently been associated with BSI and transplant-related mortality. 138 That is, conditioning regimen insult to the GI tract in combination with antibiotic use prior to neutrophil engraftment decreases microbiome diversity and increases subsequent risk for bacteremia from MBI-LCBI organisms.…”

“…138 That is, conditioning regimen insult to the GI tract in combination with antibiotic use prior to neutrophil engraftment decreases microbiome diversity and increases subsequent risk for bacteremia from MBI-LCBI organisms. 77,137,139 Loss of microbiome diversity leads to domination of MBI-LCBI pathogens within the GI tract and subsequent systemic infection with the corresponding blood pathogen. 137 This observation corroborates that neutropenia-associated BSIs arise largely from a gastrointestinal source via a transformation in the gut microbiome resulting in loss of colonization resistance and subsequent overgrowth by a single bacterial species that then translocates through damaged epithelium into the bloodstream.…”

Emergence of new infections in the 21st century and identification of pathogens using next generation sequencing

“…Moreover, all libraries report resistance to tetracycline, trimethoprim, trimethoprim sulfamethoxazole, D-cycloserine, chloramphenicol, and penicillin, and some of them report resistance to aminoglycosides, glicylcyclines and beta-lactams. About 3 % of all antibiotic resistance genes listed in those libraries are associated with mobile elements, such as transposons or integrons [108]. The effect of antibiotics on intestinal microbial communities is actively studied.…”

Gut Microbiota and Anxiety: An Exploration of Key Findings

“…In adulthood, the phyla Firmicutes and Bacteroidetes, followed by Actinobacteria and Proteobacteria, are predominant in healthy and balanced gut communities [2]. Disruptions of this critical balance are implicated in the etiology and pathogenesis of a wide range of medical conditions, including autoimmune disorders, allergies, systemic infections following cancer chemotherapy, and obesity [3][4][5][6]. There is now increasing evidence of a brain-gut-microbe connection, with results from germ free (GF) animal models and probiotic studies supporting a link between gut microbes and anxiety.…”