Some comments on certain statistical aspects of the study of the microbiome.

This note complements and clarifies part of the work of Hawinkel et al. recently published in the journal and suggests some more or less standard tools and methods for carrying out association studies of the microbiome.

A qualitative content analysis of nurses' perceptions about readiness to manage intimate partner violence.

AIMS: To explore the perceptions of nurses on the factors that influence their readiness to manage intimate partner violence (IPV) in Spain. DESIGN: Qualitative content analysis based on data from six different regions in Spain (Murcia, Region of Valencia, Castile and Leon, Cantabria, Catalonia, Aragon) collected between 2014 and 2016. METHODS: 37 personal interviews were carried out with nurses from 27 primary health care (PHC) centres and 10 hospitals. We followed the consolidated criteria for reporting qualitative research guidelines. Qualitative content analysis was supported by Atlas.ti and OpenCode. RESULTS: The results are organised into four categories corresponding to (1) acknowledging IPV as a health issue. An ongoing process; (2) the Spanish healthcare system and PHC service: a favourable space to address IPV although with some limitations; (3) nurses as a key figure for IPV in coordinated care and (4) factors involved in nurses' autonomy in their response to IPV, with their respective subcategories. CONCLUSION: In practice, nurses perceive responding to IPV as a personal choice, despite the institutional mandate to address IPV as a health issue. There is a need to increase continuous training and ensure IPV is included in the curriculum in university nursing undergraduate degrees, by disseminating the existing IPV protocols. Furthermore, coordination between healthcare professionals needs to be improved in terms of all levels of care and with other institutions.

Significant Correlation Between the Infant Gut Microbiome and Rotavirus Vaccine Response in Rural Ghana.

BACKGROUND: Rotavirus (RV) is the leading cause of diarrhea-related death in children worldwide and 95% of RV-associated deaths occur in Africa and Asia where RV vaccines (RVVs) have lower efficacy. We hypothesize that differences in intestinal microbiome composition correlate with the decreased RVV efficacy observed in poor settings. METHODS: We conducted a nested, case-control study comparing prevaccination, fecal microbiome compositions between 6-week old, matched RVV responders and nonresponders in rural Ghana. These infants' microbiomes were then compared with 154 age-matched, healthy Dutch infants' microbiomes, assumed to be RVV responders. Fecal microbiome analysis was performed in all groups using the Human Intestinal Tract Chip. RESULTS: We analyzed findings in 78 Ghanaian infants, including 39 RVV responder and nonresponder pairs. The overall microbiome composition was significantly different between RVV responders and nonresponders (FDR, 0.12), and Ghanaian responders were more similar to Dutch infants than nonresponders (P = .002). RVV response correlated with an increased abundance of Streptococcus bovis and a decreased abundance of the Bacteroidetes phylum in comparisons between both Ghanaian RVV responders and nonresponders (FDR, 0.008 vs 0.003) and Dutch infants and Ghanaian nonresponders (FDR, 0.002 vs 0.009). CONCLUSIONS: The intestinal microbiome composition correlates significantly with RVV immunogenicity and may contribute to the diminished RVV immunogenicity observed in developing countries.

Duodenal infusion of donor feces for recurrent Clostridium difficile.

BACKGROUND: Recurrent Clostridium difficile infection is difficult to treat, and failure rates for antibiotic therapy are high. We studied the effect of duodenal infusion of donor feces in patients with recurrent C. difficile infection. METHODS: We randomly assigned patients to receive one of three therapies: an initial vancomycin regimen (500 mg orally four times per day for 4 days), followed by bowel lavage and subsequent infusion of a solution of donor feces through a nasoduodenal tube; a standard vancomycin regimen (500 mg orally four times per day for 14 days); or a standard vancomycin regimen with bowel lavage. The primary end point was the resolution of diarrhea associated with C. difficile infection without relapse after 10 weeks. RESULTS: The study was stopped after an interim analysis. Of 16 patients in the infusion group, 13 (81%) had resolution of C. difficile-associated diarrhea after the first infusion. The 3 remaining patients received a second infusion with feces from a different donor, with resolution in 2 patients. Resolution of C. difficile infection occurred in 4 of 13 patients (31%) receiving vancomycin alone and in 3 of 13 patients (23%) receiving vancomycin with bowel lavage (P<0.001 for both comparisons with the infusion group). No significant differences in adverse events among the three study groups were observed except for mild diarrhea and abdominal cramping in the infusion group on the infusion day. After donor-feces infusion, patients showed increased fecal bacterial diversity, similar to that in healthy donors, with an increase in Bacteroidetes species and clostridium clusters IV and XIVa and a decrease in Proteobacteria species. CONCLUSIONS: The infusion of donor feces was significantly more effective for the treatment of recurrent C. difficile infection than the use of vancomycin. (Funded by the Netherlands Organization for Health Research and Development and the Netherlands Organization for Scientific Research; Netherlands Trial Register number, NTR1177.).

Findings From a Randomized Controlled Trial of Fecal Transplantation for Patients With Ulcerative Colitis.

BACKGROUND & AIMS: Several case series have reported the effects of fecal microbiota transplantation (FMT) for ulcerative colitis (UC). We assessed the efficacy and safety of FMT for patients with UC in a double-blind randomized trial. METHODS: Patients with mild to moderately active UC (n = 50) were assigned to groups that underwent FMT with feces from healthy donors or were given autologous fecal microbiota (control); each transplant was administered via nasoduodenal tube at the start of the study and 3 weeks later. The study was performed at the Academic Medical Center in Amsterdam from June 2011 through May 2014. The composite primary end point was clinical remission (simple clinical colitis activity index scores ≤2) combined with ≥1-point decrease in the Mayo endoscopic score at week 12. Secondary end points were safety and microbiota composition by phylogenetic microarray in fecal samples. RESULTS: Thirty-seven patients completed the primary end point assessment. In the intention-to-treat analysis, 7 of 23 patients who received fecal transplants from healthy donors (30.4%) and 5 of 25 controls (20.0%) achieved the primary end point (P = .51). In the per-protocol analysis, 7 of 17 patients who received fecal transplants from healthy donors (41.2%) and 5 of 20 controls (25.0%) achieved the primary end point (P = .29). Serious adverse events occurred in 4 patients (2 in the FMT group), but these were not considered to be related to the FMT. At 12 weeks, the microbiota of responders in the FMT group was similar to that of their healthy donors; remission was associated with proportions of Clostridium clusters IV and XIVa. CONCLUSIONS: In this phase 2 trial, there was no statistically significant difference in clinical and endoscopic remission between patients with UC who received fecal transplants from healthy donors and those who received their own fecal microbiota, which may be due to limited numbers. However, the microbiota of responders had distinct features from that of nonresponders, warranting further study. ClinicalTrials.gov Number: NCT01650038.

How to Manipulate the Microbiota: Fecal Microbiota Transplantation.

Fecal microbiota transplantation (FMT) is a rather straightforward therapy that manipulates the human gastrointestinal (GI) microbiota, by which a healthy donor microbiota is transferred into an existing but disturbed microbial ecosystem. This is a natural process that occurs already at birth; infants are rapidly colonized by a specific microbial community, the composition of which strongly depends on the mode of delivery and which therefore most likely originates from the mother (Palmer et al. 2007; Tannock et al. 1990). Since this early life microbial community already contains most, if not all, of the predominantly anaerobic microbes that are only found in the GI tract, it is reasonable to assume that early life colonization is the ultimate natural fecal transplantation.

Colonic metaproteomic signatures of active bacteria and the host in obesity.

Obesity is associated with the intestinal microbiota in humans but the underlying mechanisms are yet to be fully understood. Our previous phylogenetic study showed that the faecal microbiota profiles of nonobese versus obese and morbidly obese individuals differed. Here, we have extended this analysis with a characterization of the faecal metaproteome, in order to detect differences at a functional level. Proteins were extracted from crude faecal samples of 29 subjects, separated by 1D gel electrophoresis and characterized using RP LC-MS/MS. The peptide data were analyzed in database searches with two complementary algorithms, OMSSA and X!Tandem, to increase the number of identifications. Evolutionary genealogy of genes: nonsupervised orthologous groups (EggNOG) database searches resulted in the functional annotation of over 90% of the identified microbial and human proteins. Based on both bacterial and human proteins, a clear clustering of obese and nonobese samples was obtained that exceeded the phylogenetic separation in dimension. Moreover, integration of the metaproteomics and phylogenetic datasets revealed notably that the phylum Bacteroidetes was metabolically more active in the obese than nonobese subjects. Finally, significant correlations between clinical measurements and bacterial gene functions were identified. This study emphasizes the importance of integrating data of the host and microbiota to understand their interactions.

Aberrant gut microbiota composition at the onset of type 1 diabetes in young children.

AIMS/HYPOTHESIS: Recent studies indicate that an aberrant gut microbiota is associated with the development of type 1 diabetes, yet little is known about the microbiota in children who have diabetes at an early age. To this end, the microbiota of children aged 1-5 years with new-onset type 1 diabetes was compared with the microbiota of age-matched healthy controls. METHODS: A deep global analysis of the gut microbiota composition was established by phylogenetic microarray analysis using a Human Intestinal Tract Chip (HITChip). RESULTS: Principal component analyses highlighted the importance of age when comparing age-matched pairs. In pairs younger than 2.9 years, the combined abundance of the class Bacilli (notably streptococci) and the phylum Bacteroidetes was higher in diabetic children, whereas the combined abundance of members of Clostridium clusters IV and XIVa was higher in the healthy controls. Controls older than 2.9 years were characterised by a higher fraction of butyrate-producing species within Clostridium clusters IV and XIVa than was seen in the corresponding diabetic children or in children from the younger age groups, while the diabetic children older than 2.9 years could be differentiated by having an increased microbial diversity. CONCLUSIONS/INTERPRETATION: The results from both age groups suggest that non-diabetic children have a more balanced microbiota in which butyrate-producing species appear to hold a pivotal position.

Impact of oral vancomycin on gut microbiota, bile acid metabolism, and insulin sensitivity.

BACKGROUND & AIMS: Obesity has been associated with changes in the composition and function of the intestinal microbiota. Modulation of the microbiota by antibiotics also alters bile acid and glucose metabolism in mice. Hence, we hypothesized that short term administration of oral antibiotics in humans would affect fecal microbiota composition and subsequently bile acid and glucose metabolism. METHODS: In this single blinded randomized controlled trial, 20 male obese subjects with metabolic syndrome were randomized to 7 days of amoxicillin 500 mg t.i.d. or 7 days of vancomycin 500 mg t.i.d. At baseline and after 1 week of therapy, fecal microbiota composition (Human Intestinal Tract Chip phylogenetic microarray), fecal and plasma bile acid concentrations as well as insulin sensitivity (hyperinsulinemic euglycemic clamp using [6,6-(2)H2]-glucose tracer) were measured. RESULTS: Vancomycin reduced fecal microbial diversity with a decrease of gram-positive bacteria (mainly Firmicutes) and a compensatory increase in gram-negative bacteria (mainly Proteobacteria). Concomitantly, vancomycin decreased fecal secondary bile acids with a simultaneous postprandial increase in primary bile acids in plasma (p<0.05). Moreover, changes in fecal bile acid concentrations were predominantly associated with altered Firmicutes. Finally, administration of vancomycin decreased peripheral insulin sensitivity (p<0.05). Amoxicillin did not affect any of these parameters. CONCLUSIONS: Oral administration of vancomycin significantly impacts host physiology by decreasing intestinal microbiota diversity, bile acid dehydroxylation and peripheral insulin sensitivity in subjects with metabolic syndrome. These data show that intestinal microbiota, particularly of the Firmicutes phylum contributes to bile acid and glucose metabolism in humans. This trial is registered at the Dutch Trial Register (NTR2566).

Characterization of Romboutsia ilealis gen. nov., sp. nov., isolated from the gastro-intestinal tract of a rat, and proposal for the reclassification of five closely related members of the genus Clostridium into the genera Romboutsia gen. nov., Intestinibacter gen. nov., Terrisporobacter gen. nov. and Asaccharospora gen. nov.

A Gram-positive staining, rod-shaped, non-motile, spore-forming obligately anaerobic bacterium, designated CRIBT, was isolated from the gastro-intestinal tract of a rat and characterized. The major cellular fatty acids of strain CRIBT were saturated and unsaturated straight-chain C12-C19 fatty acids, with C16:0 being the predominant fatty acid. The polar lipid profile comprised six glycolipids, four phospholipids and one lipid that did not stain with any of the specific spray reagents used. The only quinone was MK-6. The predominating cell-wall sugars were glucose and galactose. The peptidoglycan type of strain CRIBT was A1σ lanthionine-direct. The genomic DNA G+C content of strain CRIBT was 28.1 mol%. On the basis of 16S rRNA gene sequence similarity, strain CRIBT was most closely related to a number of species of the genus Clostridium, including Clostridium lituseburense (97.2%), Clostridium glycolicum (96.2%), Clostridium mayombei (96.2%), Clostridium bartlettii (96.0%) and Clostridium irregulare (95.5%). All these species show very low 16S rRNA gene sequence similarity (<85%) to the type strain of Clostridium butyricum, the type species of the genus Clostridium. DNA-DNA hybridization with closely related reference strains indicated reassociation values below 32%. On the basis of phenotypic and genetic studies, a novel genus, Romboutsia gen. nov., is proposed. The novel isolate CRIBT (=DSM 25109T=NIZO 4048T) is proposed as the type strain of the type species, Romboutsia ilealis gen. nov., sp. nov., of the proposed novel genus. It is proposed that C. lituseburense is transferred to this genus as Romboutsia lituseburensis comb. nov. Furthermore, the reclassification into novel genera is proposed for C. bartlettii, as Intestinibacter bartlettii gen. nov., comb. nov. (type species of the genus), C. glycolicum, as Terrisporobacter glycolicus gen. nov., comb. nov. (type species of the genus), C. mayombei, as Terrisporobacter mayombei gen. nov., comb. nov., and C. irregulare, as Asaccharospora irregularis gen. nov., comb. nov. (type species of the genus), on the basis of additional data collected in this study. In addition, an emendation of the species Peptostreptococcus anaerobius and the order Eubacteriales is provided.

Insight into the prebiotic concept: lessons from an exploratory, double blind intervention study with inulin-type fructans in obese women.

OBJECTIVE: To highlight the contribution of the gut microbiota to the modulation of host metabolism by dietary inulin-type fructans (ITF prebiotics) in obese women. METHODS: A double blind, placebo controlled, intervention study was performed with 30 obese women treated with ITF prebiotics (inulin/oligofructose 50/50 mix; n=15) or placebo (maltodextrin; n=15) for 3 months (16 g/day). Blood, faeces and urine sampling, oral glucose tolerance test, homeostasis model assessment and impedancemetry were performed before and after treatment. The gut microbial composition in faeces was analysed by phylogenetic microarray and qPCR analysis of 16S rDNA. Plasma and urine metabolic profiles were analysed by 1H-NMR spectroscopy. RESULTS: Treatment with ITF prebiotics, but not the placebo, led to an increase in Bifidobacterium and Faecalibacterium prausnitzii; both bacteria negatively correlated with serum lipopolysaccharide levels. ITF prebiotics also decreased Bacteroides intestinalis, Bacteroides vulgatus and Propionibacterium, an effect associated with a slight decrease in fat mass and with plasma lactate and phosphatidylcholine levels. No clear treatment clustering could be detected for gut microbial analysis or plasma and urine metabolomic profile analyses. However, ITF prebiotics led to subtle changes in the gut microbiota that may importantly impact on several key metabolites implicated in obesity and/or diabetes. CONCLUSIONS: ITF prebiotics selectively changed the gut microbiota composition in obese women, leading to modest changes in host metabolism, as suggested by the correlation between some bacterial species and metabolic endotoxaemia or metabolomic signatures.

Exploring host-commensal-pathogen dynamics in cell line and organotypic human intestinal epithelial models.

Host and microbiome intricately interact in the ecosystem of the human digestive tract, playing a crucial role in our health. These interactions can initiate immune responses in the epithelial cells, which, in turn, activate downstream responses in other immune cells. Here, we used a CaCo-2 and a human intestinal enteroid (HIE) model to explore epithelial responses to both commensal and pathogenic bacteria, individually and combined. CaCo-2 cells were co-cultured with peripheral blood mononuclear cells, revealing downstream activation of immune cells. While both systems showed comparable cytokine profiles, they differed in their responses to the different bacteria, with the organoid system being more representative of responses observed in humans. We provide evidence of the pro-inflammatory responses associated with these bacteria. These models contribute to a deeper understanding of the interactions between the microbiota, intestinal epithelium, and immune cells in the gut, promoting advances in the field of host-microbe interactions.

Reducing bias in microbiome research: Comparing methods from sample collection to sequencing.

Background: Microbiota profiles are strongly influenced by many technical aspects that impact the ability of researchers to compare results. To investigate and identify potential biases introduced by technical variations, we compared several approaches throughout the entire workflow of a microbiome study, from sample collection to sequencing, using commercially available mock communities (from bacterial strains as well as from DNA) and multiple human fecal samples, including a large set of positive controls created as a random mix of several participant samples. Methods: Human fecal material was sampled, and aliquots were used to test two commercially available stabilization solutions (OMNIgene·GUT and Zymo Research) in comparison to samples frozen immediately upon collection. In addition, the methodology for DNA extraction, input of DNA, or the number of PCR cycles were analyzed. Furthermore, to investigate the potential batch effects in DNA extraction, sequencing, and barcoding, we included 139 positive controls. Results: Samples preserved in both the stabilization buffers limited the overgrowth of Enterobacteriaceae when compared to unpreserved samples stored at room temperature (RT). These stabilized samples stored at RT were different from immediately frozen samples, where the relative abundance of Bacteroidota was higher and Actinobacteriota and Firmicutes were lower. As reported previously, the method used for cell disruption was a major contributor to variation in microbiota composition. In addition, a high number of cycles during PCR lead to an increase in contaminants detected in the negative controls. The DNA extraction had a significant impact on the microbial composition, also observed with the use of different Illumina barcodes during library preparation and sequencing, while no batch effect was observed in replicate runs. Conclusion: Our study reaffirms the importance of the mechanical cell disruption method and immediate frozen storage as critical aspects in fecal microbiota studies. A comparison of storage conditions revealed that the bias was limited in RT samples preserved in stabilization systems, and these may be a suitable compromise when logistics are challenging due to the size or location of a study. Moreover, to reduce the effect of contaminants in fecal microbiota profiling studies, we suggest the use of ~125 pg input DNA and 25 PCR cycles as optimal parameters during library preparation.

A tool to assess the mock community samples in 16S rRNA gene-based microbiota profiling studies.

Inclusion and investigation of technical controls in microbiome sequencing studies is important for understanding technical biases and errors. Here, we present chkMocks, a general R-based tool that allows researchers to compare the composition of mock communities that are processed along with samples to their theoretical composition. A visual comparison between experimental and theoretical community composition and their correlation is provided for researchers to assess the quality of their sample processing workflows.

Design and implementation of a "crisis resource management" training program for the initial assessment of polytrauma patients.

INTRODUCTION: To describe the design and implementation of a Crisis Resource Management (CRM) training program for the initial assessment of polytrauma patients. METHODS: Prospectively implemented CRM training program in acute-care tertiary hospital by hospital personnel involved in the care of polytraumatisms. The program has a blended format and 23-h duration, including 11 h of online theoretical training followed by 12-h simulation modules and practical cases devoted to the roles of members of the trauma team, functioning of the polytrauma room, and key aspects of teamwork. The Human Factors Attitude Survey (HFAS) was used to assess attitudes related to non-technical skills, and the End-of-Course Critique (ECC) survey to evaluate satisfaction with training. We evaluated changes in the pre- and post-training assessments. RESULTS: Eighty staff personnel (26% specialists, 16% residents, 29% nurses, 14% nursing assistant, 15% stretcher bearer) participated in three editions of the program. Theoretical knowledge improved from a mean (SD) of 5.95 (1.7) to 8.27 (2.1) (P < .0001). In the HFAS, statistically significant differences in 18 of 23 attitudinal markers were observed, with improvements in all items of "leadership" and "roles", in 4 of 5 items of "situational awareness", and in 4 of 8 items of "communication". Mean values obtained in the ECC questionnaire were also very high. CONCLUSIONS: A CRM training model developed for the initial care of polytrauma patients improved theoretical knowledge and participants perceptions and attitudes regarding leadership, communication, roles, and situational awareness of members of the trauma team.

Wavelet clustering analysis as a tool for characterizing community structure in the human microbiome.

Human microbiome research is helped by the characterization of microbial networks, as these may reveal key microbes that can be targeted for beneficial health effects. Prevailing methods of microbial network characterization are based on measures of association, often applied to limited sampling points in time. Here, we demonstrate the potential of wavelet clustering, a technique that clusters time series based on similarities in their spectral characteristics. We illustrate this technique with synthetic time series and apply wavelet clustering to densely sampled human gut microbiome time series. We compare our results with hierarchical clustering based on temporal correlations in abundance, within and across individuals, and show that the cluster trees obtained by using either method are significantly different in terms of elements clustered together, branching structure and total branch length. By capitalizing on the dynamic nature of the human microbiome, wavelet clustering reveals community structures that remain obscured in correlation-based methods.

Associations and recovery dynamics of the nasopharyngeal microbiota during influenza-like illness in the aging population.

Influenza-like illness (ILI), a disease caused by respiratory pathogens including influenza virus, is a major health concern in older adults. There is little information on changes and recovery dynamics of the nasopharyngeal (NP) microbiota of older adults associated with an ILI. Here, we compared the NP microbiota in older adults reporting (n = 240) or not (n = 157) ILI during the 2014-2015 influenza season at different times of the ILI event. A small but significant effect of the ILI was observed on the microbiota community composition and structure when compared to controls and samples collected at recovery. Corynebacterium was negatively associated with ILI and its abundance increased after recovery. Potential pathobionts such as Haemophilus, Porphyromonas and Gemella had higher abundances during acute-ILI. Stability and changes in the NP microbial community showed individual dynamics. Key core genera, Corynebacterium, Moraxella and Dolosigranulum exhibited higher inter-individual variability in acute-ILI, but showed comparable variability to controls after recovery. Participants in the ILI group with higher core microbiota abundances at the acute phase showed higher microbiota stability after recovery. Our findings demonstrate that acute-ILI is associated with alterations in the phylogenetic structure of the NP microbiota in older adults. The variation in the core microbiota suggests imbalances in the ecosystem, which could potentially play a role in the susceptibility and recovery of the NP microbiota after an ILI event.

Mode of delivery modulates the intestinal microbiota and impacts the response to vaccination.

The gut microbiota in early life, when critical immune maturation takes place, may influence the immunogenicity of childhood vaccinations. Here we assess the association between mode of delivery, gut microbiota development in the first year of life, and mucosal antigen-specific antibody responses against pneumococcal vaccination in 101 infants at age 12 months and against meningococcal vaccination in 66 infants at age 18 months. Birth by vaginal delivery is associated with higher antibody responses against both vaccines. Relative abundances of vaginal birth-associated Bifidobacterium and Escherichia coli in the first weeks of life are positively associated with anti-pneumococcal antibody responses, and relative abundance of E. coli in the same period is also positively associated with anti-meningococcal antibody responses. In this study, we show that mode of delivery-induced microbiota profiles of the gut are associated with subsequent antibody responses to routine childhood vaccines.

Species-Specific Patterns of Gut Metabolic Modules in Dutch Individuals with Different Dietary Habits.

Diet is an important determinant of the human gut microbiome. Here, we analyzed fecal metagenomes of Dutch adults following omnivorous, pescatarian, vegan, and vegetarian diets. We compared the taxonomic composition of individuals from our study with publicly available gut metagenomes from westernized and non-westernized societies. We observed that, despite long-term transition to diets rich in plant fibers (vegan or vegetarian), the microbiomes of these were typical of westernized populations, and similar in composition to omnivores. Although there were no major differences in metabolic modules, we identified differences in the species that contributed to particular functions, such as carbohydrate degradation and short-chain fatty acid metabolism. Overall, this study shows functional redundancy of the microbiomes among westernized populations, which is independent of long-term individual dietary habits. IMPORTANCE Diet is an important modulator of the human gut microbiome, which is susceptible to increased consumption of plant fibers in vegan or vegetarian lifestyles. To investigate this, we compared the gut microbiome of Dutch adults following omnivorous, pescatarian, vegan and vegetarian diets. We did not observe major differences in the gut microbiome composition and function between individuals with different dietary habits. However, we observed differences in the species that contribute to the core functions of the gut microbiome. Our study thus emphasizes the need to better understand the species-specific functional changes associated with dietary habits in the human gut microbiome.