Objective Infection with Helicobacter pylori ( H pylori ), especially cytotoxin‐associated gene A‐positive (CagA+) strains, has been associated with various gastrointestinal and extragastric diseases. The aim of this study was to characterize H pylori ‐induced alterations in the gastric and tongue coating microbiota and evaluate their potential impacts on human health. Design The gastric mucosa and tongue coating specimens were collected from 80 patients with chronic gastritis, and microbiota profiles were generated by 16S rRNA gene sequencing. Samples were grouped as H pylori negative (n = 32), CagA‐negative H pylori infection (n = 13), and CagA‐positive H pylori infection (n=35). The comparison of bacterial relative abundance was made using a generalized linear model. Functional profiling of microbial communities was predicted with PICRUSt and BugBase. Microbial correlation networks were produced by utilizing SparCC method. Results Significant alterations of the gastric microbiota were found in the H pylori +/CagA+ samples, represented by a decrease in bacterial diversity, a reduced abundance of Roseburia , and increased abundances of Helicobacter and Haemophilus genera. At the community level, functions involved in biofilm forming, mobile element content, and facultative anaerobiosis were significantly decreased in gastric microbiome of the H pylori + subjects. The presence of CagA gene was linked to an increased proportion of Gram‐negative bacteria in the stomach, thereby contributing to an upregulation of lipopolysaccharide (LPS) biosynthesis. The number of bacterial interactions was greatly reduced in networks of both tongue coating and gastric microbiota of the H pylori +/CagA+ subject, and the cooperative bacterial interactions dominated the tongue coating microbiome. Conclusions Infection with H pylori strains possessing CagA may increase the risk of various diseases, by upregulating LPS biosynthesis in the stomach and weakening the defense of oral microbiota against microorganisms with pathogenic potential.

Temporal development of the human gut microbiome from infancy to childhood is driven by a variety of factors. We surveyed the fecal microbiome of 729 Chinese children aged 0-36 months, aiming to identify the age-specific patterns of microbiota succession, and evaluate the impact of birth mode, gender, geographical location, and gastrointestinal tract symptoms on the shaping of the gut microbiome. We demonstrated that phylogenetic diversity of the gut microbiome increased gradually over time, which was accompanied by an increase in Bacteroidetes and a reduction in Proteobacteria species. Analysis of community-wide phenotypes revealed a succession from aerobic bacteria and anaerobic bacteria to facultative anaerobes, and from Gramnegative to Gram-positive species during gut microbiota development in early childhood. The metabolic functions of the gut microbiome shifted tremendously alongside early physiological development, including an increase in alanine, aspartate, and glutamate metabolism, and a reduction in glutathione, fatty acid, and tyrosine metabolism. During the first year of life, the Bacteroidetes phylum was less abundant in children born by casarean section compared with those delivered vaginally. The Enterococcaceae family, a group of facultative anaerobic microorganisms with pathogenic potential, was predominant in preterm infants. No measurable effect of maternal antibiotic exposure on gut microbiota development was found in the first 3 years of life. The relative abundances of Coriobacteriaceae and Streptococcaceae families, and Megasphaera genus were found to be higher in girls than in boys. Among the three first-tier Chinese cities, children born and fed in Beijing had a higher abundance of Enterococcaceae and Lachnospiraceae families, and Shenzhen children had a higher abundance of Fusobacteriaceae. The families Alcaligenaceae, Bacteroidaceae, and Porphyromonadaceae were more abundant in children with constipation, whereas the relative abundance of the Clostridium genus was higher in those with diarrhea.

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Liver health, fecal bile acid (BA) concentrations, and gut microbiota composition are closely connected. BAs and the microbiome influence each other in the gut, where bacteria modify the BA profile, while intestinal BAs regulate the growth of commensal bacteria, maintain the barrier integrity, and modulate the immune system. Previous studies have found that the co-occurrence of gut microbiota dysbiosis and BA metabolism alteration is present in many human liver diseases. Our study is the first to assess the gut microbiota composition in infantile cholestatic jaundice (CJ) and elucidate the linkage between gut bacterial changes and alterations of BA metabolism. We observed reduced levels of primary BAs and most secondary BAs in infants with CJ. The reduced concentration of fecal BAs in infantile CJ was associated with the overgrowth of gut bacteria with a pathogenic potential and the depletion of those with a potential benefit. The altered gut microbiota of infants with CJ likely upregulates the conversion from primary to secondary BAs. Our study provides a new perspective on potential targets for gut microbiota intervention directed at the management of infantile CJ.

Fecal microbiota transplantation (FMT) has been shown as an effective treatment for recurrent clostridium difficile infection (RCDI) in adults. In this study, we aim to evaluate the clinical efficacy of FMT in treating children with RCDI, and explore fecal microbiota changes during FMT treatment. A total of 11 RCDI subjects with a median age of 3.5 years were enrolled in this single-center prospective pilot study. All patients were cured (11/11, 100%) by FMT either through upper gastrointestinal tract route with a nasointestinal tube (13/16, 81.2%) or lower gastrointestinal tract route with a rectal tube (3/16, 18.8%). The cure rate of single FMT was 63.6% (7/11), and 4 (4/11, 36.4%) cases were performed with 2 or 3 times of FMT. Mild adverse events were reported in 4 children (4/11, 36.4%), including transient diarrhea, mild abdominal pain, transient fever and vomit. Gut microbiota composition analysis of 59 fecal samples collected from 34 participants (9 RCDI children, 9 donors and 16 health controls) showed that the alpha diversity was lower in pediatric RCDI patients before FMT than the healthy controls and donors, and fecal microbial community of pre-FMT samples (beta diversity) was apart from that of healthy controls and donors. No significant differences in alpha diversity, beta diversity or phylogenetic distance were detected between donors and healthy controls. Both the richness and diversity of gut microbiota were improved in the pediatric RCDI patients after FMT, and the bacteria community was shifted closer to the donor and healthy control group. Furthermore, FMT re-directed gut microbiome functions of pediatric RCDI toward a health state. Our results indicate that it is safe and tolerant to use FMT in treating pediatric RCDI. FMT shifted the gut microbiome composition and function in children with RCDI toward a healthy state.