Update on Fecal Microbiota Transplantation 2015: Indications, Methodologies, Mechanisms, and Outlook

A role for bacterial urease in gut dysbiosis and Crohn's disease

Gut dysbiosis during inflammatory bowel disease involves alterations in the gut microbiota associated with inflammation of the host gut. We used a combination of shotgun metagenomic sequencing and metabolomics to analyze fecal samples from pediatric patients with Crohn's disease and found an association between disease severity, gut dysbiosis, and bacterial production of free amino acids. Nitrogen flux studies using 15N in mice showed that activity of bacterial urease, an enzyme that releases ammonia by hydrolysis of host urea, led to the transfer of murine host-derived nitrogen to the gut microbiota where it was used for amino acid synthesis. Inoculation of a conventional murine host (pretreated with antibiotics and polyethylene glycol) with commensal Escherichia coli engineered to express urease led to dysbiosis of the gut microbiota, resulting in a predominance of Proteobacteria species. This was associated with a worsening of immune-mediated colitis in these animals. A potential role for altered urease expression and nitrogen flux in the development of gut dysbiosis suggests that bacterial urease may be a potential therapeutic target for inflammatory bowel diseases.

Microbiota Replacement Therapies: Innovation in Gastrointestinal Care

There has been an increasing interest in the association between human disease and altered gut microbiota, and therapeutics to modulate microbiota to treat disease. Healthy human gastrointestinal microbiota is highly diverse and rich, and harbors between 500 and 2,000 species. Diseases associated with dysbiotic microbiota include antibiotic-associated diarrhea, Clostridium difficile infection, multidrug-resistant organisms, inflammatory bowel disease, obesity, metabolic syndrome, diabetes mellitus, neuropsychiatric diseases, and systemic autoimmune diseases. Microbiota replacement therapies have shown immense promise in treatment of recurrent C. difficile infection and are being studied for other indications. Microbiota replacement therapies for indications other than C. difficile infection should be performed only in research settings. There is an immense need for standardized microbiota replacement therapies for C. difficile infection. Studies are needed to elucidate long-term safety and adverse events from these therapies.

Faecal microbiota transplantation: establishment of a clinical application framework

BACKGROUND

Faecal microbiota transplantation (FMT) is currently being established as a second-line treatment for recurrent Clostridium difficile infection. FMT is further being considered for other infectious and inflammatory conditions. Safe and reproducible methods for donor screening, laboratory processing and clinical application of FMT are warranted.

METHODS

Here, we describe the development of a complete clinical application framework for FMT. The framework has been developed to comply with the European Tissue Act, thus considering donor faeces for FMT comparable to a human tissue and not a drug.

RESULTS

Recruitment and screening of potential faeces donors took place in the public blood donor setting and consisted of questionnaires, blood sampling and faecal sample analysis. Once approved, and following their written informed consent, eligible donors were invited for voluntary faecal donation. Laboratory processing protocols describe the initial handling, cryopreservation and thawing for clinical application. The clinical FMT procedures took place in a gastroenterological setting using a nasojejunal tube or colonoscopy, and follow-ups were performed at 1, 8 and 26 weeks after FMT. Complete traceability of essential equipment, faecal samples and donor-recipient matching data will be maintained and secured for 30 years.

CONCLUSION

A clinical FMT service should be consolidated by a complete documentation system that complies with the European Tissue Act. In this paper, we provide a description of such a framework.

Faecal microbiota transplantation in patients with Clostridium difficile and significant comorbidities as well as in patients with new indications: A case series

Fecal microbiota transplantation (FMT) is effective in recurrent Clostridium difficile infection (rCDI). Knowledge of the safety and efficacy of FMT treatment in immune deficient patients is scarce. FMT has been suggested as a potential method for an increasing number of new indications besides rCDI. Among our FMT-treated rCDI patients, we reviewed those with major comorbidities: two human immunodeficiency virus patients, six haemodialysis patients, two kidney transplant patients, two liver transplant patients and a patient with chronic lymphatic leukaemia. We also reviewed those treated with FMT for indications other than rCDI: Salmonella carriage (two patients), trimethylaminuria (two patients), small intestinal bacterial overgrowth (SIBO; one patient), and lymphocytic colitis (one patient), as well as a common variable immunodeficiency patient with chronic norovirus infection and ESBL-producing Escherichia coli (E. coli) carriage. Of the thirteen rCDI patients treated with FMT, eleven cleared the CDI. The observed adverse events were not directly attributable to FMT. Concerning the special indications, both Salmonellas and ESBL-producing E. coli were eradicated. One trimethylaminuria patient and one SIBO-patient reported a reduction of symptoms. Three patients did not experience a benefit from FMT: chronic norovirus, lymphocytic colitis and the other fish malodour syndrome. There were no reported side effects in this group. FMT appeared to be safe and effective for immunocompromised patients with rCDI. FMT showed promise for the eradication of antibiotic-resistant bacteria, but further research is warranted.

Systematic Review and Meta-analysis: Fecal Microbiota Transplantation for Treatment of Active Ulcerative Colitis

BACKGROUND

Changes in the colonic microbiota may play a role in the pathogenesis of ulcerative colitis (UC) and restoration of healthy gut microbiota may ameliorate disease. A systematic review and meta-analysis was conducted to assess fecal microbiota transplantation (FMT) as a treatment for active UC.

METHODS

A literature search was conducted to identify high-quality studies of FMT as a treatment for patients with UC. The primary outcome was combined clinical remission and endoscopic remission or response. Secondary outcomes included clinical remission, endoscopic remission, and serious adverse events. Odds ratios with 95% confidence intervals (CIs) are reported.

RESULTS

Overall, 4 studies with 277 participants were eligible for inclusion. Among 4 randomized controlled trials, FMT was associated with higher combined clinical and endoscopic remission compared with placebo (risk ratio UC not in remission was 0.80; 95% CI: 0.71-0.89) with a number needed to treat of 5 (95% CI: 4-10). There was no statistically significant increase in serious adverse events with FMT compared with controls (risk ratio adverse event was 1.4; 95% CI: 0.55-3.58).

CONCLUSIONS

Among randomized controlled trials, short-term use of FMT shows promise as a treatment to induce remission in active UC based on the efficacy and safety observed. However, there remain many unanswered questions that require further research before FMT can be considered for use in clinical practice.

Oral microbiota transplant: a potential new therapy for oral diseases

Dental caries and periodontitis are amongst the most common diseases affecting humans worldwide. There is an evolving trend for dental and medical research to share knowledge on the etiology and promising therapies for human diseases. Inspired by the success of fecal microbiota transplant to manage gastro-intestinal disordes, oral microbiome transplant has been proposed but not yet tested in humans. This article critically reviews the potential of oral microbiome transplant for managing oral diseases.

Clinical Practice and Infrastructure Review of Fecal Microbiota Transplantation for Clostridium difficile Infection

A substantial proportion of Clostridium difficile infection (CDI) cases recur after completion of antibiotic therapy, and antibiotic cure rates diminish with each recurrence of CDI. Fecal microbiota transplantation (FMT) is an effective therapy for recurrent FMT, which otherwise requires prolonged or indefinite antibiotic treatment. FMT is performed by introducing the fecal microbial community obtained from a healthy donor or pool of donors into the stomach, small intestine, or colon of a patient with CDI. Multiple clinical trials support the usefulness of FMT in treating recurrent CDI, and CDI treatment guidelines now include consideration of FMT at the third CDI recurrence. However, there remain challenges to incorporating FMT into clinical practice. First, methods of fecal bacterial community processing vary, as do methods of FMT administration. Second, the optimal dosing strategy and expected benefit of FMT for refractory CDI, particularly for severe and severe complicated cases, are uncertain. Third, the US Food and Drug Administration (FDA) considers FMT an investigational treatment. Fourth, insurance reimbursement for FMT usually falls short of FMT administration costs. In the setting of rising C difficile incidence and growing evidence for FMT efficacy, the demand for FMT has increased. However, uncertainty surrounding optimal FMT preparation and administration methods, FDA oversight, and insurance reimbursement presently limits the clinical practice of FMT.

Role of the gastrointestinal microbiota in small animal health and disease

There is a large and emerging interest in the role of the gastrointestinal microbiota in health and disease. This paper serves to review the current knowledge and recommendations of the gastrointestinal microbiota in health and gastrointestinal disease. Further, this review evaluates the current literature and suggests guidelines for faecal microbial transplantation, a novel therapy for dysbiosis in veterinary medicine.

The risk of inflammatory bowel disease flares after fecal microbiota transplantation: Systematic review and meta-analysis

Several studies have suggested worsening in inflammatory bowel disease (IBD) activity following fecal microbiota transplantation (FMT). We aimed to assess the risk of worsening in IBD activity following FMT. An electronic search was conducted using MEDLINE (1946-June 2016), EMBASE (1954-June 2016) and Cochrane Central Register of Controlled Trials (2016). Studies in which FMT was provided to IBD patients for IBD management or (Clostridium difficile infection) CDI treatment were included. The primary outcome was the rate of worsening in IBD activity.

RESULTS

Twenty-nine studies with 514 FMT-treated IBD patients were included. Range of follow up was 4 weeks to 3 y. The pooled rate of IBD worsening was 14.9% (95% CI 10-21%). Heterogeneity was detected: I2 D 52.1%, Cochran Q test D 58.1, p D 0.01. A priori subgroup analyses were performed. Although not significant, the pooled rate of worsening in IBD activity following FMT for CDI (22.7% (95% CI: 13-36%)) was higher compared with FMT for IBD (11.1% (95% CI 7-17%)). Rates of worsening in IBD after lower GI FMT delivery revealed a higher rate of worsening in IBD activity (16.5% (95% CI: 11-24%)) compared with upper GI delivery (5.6% (95% CI: 2-16%)). Rates of worsening in high quality studies and randomized controls trials (RCTS) suggested a marginal risk of worsening in IBD activity (4.6%, (95% CI: 1.8-11%). Rates of IBD worsening are overall marginal across high quality RCTS. It is unknown if the FMT itself led to the worsening of IBD in this small fraction or if this represents alternative etiologies.

Investigation into the stability and culturability of Chinese enterotypes

Although many gut microbial enterotypes have been reported in Europe, Africa and the U.S., their effects on human health are still not yet clear. Culturing gut microbial enterotypes in vitro will be helpful to study their effects and applications. Here, fecal samples from 13 healthy Chinese volunteers were collected and subjected to next-generation sequencing. The results showed that seven of these samples belong to the Bacteroides enterotype and another six to the Prevotella enterotype. Stability of these Chinese gut microbial enterotypes was also evaluated. Results showed that most of the tested volunteer gut microbiota to be very stable. For one volunteer, the bacterial community returned to the state it was in before intestinal lavage and antibiotics treatment after four months. XP medium was found effective for simulating the Bacteroides enterotype independent of the original gut microbial community in an in vitro chemostat culture system. Although, the Prevotella enterotype was not very well simulated in vitro, different culture elements selectively enriched different gut bacteria. Pectin and xylan were found to be related to the enrichment of the genera Bacteroides, Sutterella, and Flavonifractor in this chemostat culture system.

Recent Advances and Understanding of Using Probiotic-Based Interventions to Restore Homeostasis of the Microbiome for the Prevention/Therapy of Bacterial Diseases

The importance of the microbiome in health and disease has galvanized interest in using manipulations of the gastrointestinal ecosystem to prevent and/or combat gut bacterial infections and to restore mucosal homeostasis in patients with generalized microbial imbalances (i.e., dysbiosis), including the human inflammatory bowel diseases, Crohn's disease, and ulcerative colitis. Probiotics, prebiotics, or their combination use (i.e., synbiotics) are one mechanism for modifying the microbiota and exerting direct and indirect effects on the host immune responses and metabolomics profiles. These beneficial effects are transferred through various pathways, including the production of antimicrobial peptides, promoting the growth of beneficial microbes and enhancing immunomodulatory functions via various metabolites. While probiotic therapy has been used empirically for decades with mixed success, the recent advances in molecular and mass spectrophotometric techniques for the characterization of the complexity and diversity of the intestinal microbiome has aided in better understanding of host-microbe interactions. It is important to better understand the functional properties of the microbiome, because it is now clear that the microbiota secretes many metabolites that have a direct impact on host immune responses. This information will improve selection of the most appropriate probiotic strains that selectively target intestinal disease processes.

Preparing the Gut with Antibiotics Enhances Gut Microbiota Reprogramming Efficiency by Promoting Xenomicrobiota Colonization

Gut microbiota plays multiple important roles in intestinal and physiological homeostasis, and using fecal microbiota transplantation (FMT) to reprogram gut microbiota has demonstrated promise for redressing intestinal and physiological disorders. This study tested the alterations in reprogramming efficiency caused by different gut preparation procedures and explored the associated underlying mechanisms. We prepared the guts of mice for FMT by administering one of the three most-clinically used pretreatments [antibiotics, bowel cleansing (BC) solution, or no pretreatment], and we found that preparing the gut with antibiotics induced a more efficient modification of the gut bacterial community than was induced by either of the other two pretreatment types. The increased efficiency of antibiotic treatment appeared to occur via increasing the xenomicrobiota colonization. Further analysis demonstrated that antibiotic treatment of mice induced intestinal microbiota disruption, mostly by expelling antibiotic-sensitive bacteria, while the indigenous microbiota was maintained after treatment with a BC solution or in the absence of pretreatment. The amount of antibiotic-resistant bacteria increased shortly after antibiotics usage but subsequently decreased after FMT administration. Together, these results suggest that FMT relied on the available niches in the intestinal mucosa and that preparing the gut with antibiotics facilitated xenomicrobiota colonization in the intestinal mucosa, which thus enhanced the overall gut microbiota reprogramming efficiency.

Can fecal microbiota transplantation cure irritable bowel syndrome?

AIM

To verify the utility of treatment with fecal microbiota transplantation (FMT) in patients with irritable bowel syndrome (IBS).

METHODS

We searched EMBASE, Cochrane Library and PubMed in March, 2017. The reviewed literature was based on two systematic searches in each of the databases. The MeSH terms used were IBS and fecal microbiota transplantation and the abbreviations IBS and FMT. Reference lists from the articles were reviewed to identify additional pertinent articles.

RESULTS

A total of six conference abstracts, one case report, one letter to the editor, and one clinical review were included. In the final analysis, treatment of 48 patients was evaluated. Treatment revealed an improvement in 58% of cases. The varying structure of the nine included studies must be taken into consideration.

CONCLUSION

Data on FMT and IBS are too limited to draw sufficient conclusions. Standardized double blinded randomized clinical trials need to be carried out to evaluate the effect of FMT on IBS.

How Chinese clinicians face ethical and social challenges in fecal microbiota transplantation: a questionnaire study

BACKGROUND

Fecal microbiota transplantation (FMT) is reportedly the most effective therapy for relapsing Clostridium Difficile infection (CDI) and a potential therapeutic option for many diseases. It also poses important ethical concerns. This study is an attempt to assess clinicians' perception and attitudes towards ethical and social challenges raised by fecal microbiota transplantation.

METHODS

A questionnaire was developed which consisted of 20 items: four items covered general aspects, nine were about ethical aspects such as informed consent and privacy issues, four concerned social and regulatory issues, and three were about an FMT bank. This was distributed to participants at the Second China gastroenterology and FMT conference in May 2015. Basic descriptive statistical analyses and simple comparative statistical tests were performed.

RESULTS

Nearly three quarters of the 100 respondents were gastro-enterologist physicians. 89% of all respondents believed FMT is a promising treatment modality for some diseases and 88% of whom chose clinical efficacy as the primary reason for recommending FMT. High expectation from patients and pressure on clinicians (33%) was reported as the most frequent reasons for not recommending FMT. The clinicians who had less familiarity with FMT reported significantly more worry related to the dignity and psychological impact of FMT compared to those who have high familiarity with FMT (51.6% vs 27.8%, p = 0.021).More than half of the respondents (56.1%) were concerned about the commercialization of FMT, although almost one in five respondents did not see this as a problem.

CONCLUSIONS

We found most respondents have positive attitudes towards FMT but low awareness of published evidence. Informed consent for vulnerable patients, privacy and protection of donors were perceived as the most challenging ethical aspects of FMT. This study identified areas of limited knowledge and ways of addressing ethical issues and indicates the need to devise the education and training for clinicians on FMT.

Gut microbiota and acute graft-versus-host disease

Although allogeneic stem cell transplantation (allo-SCT) is a potentially curative treatment for various hematological diseases, acute graft-versus-host disease (GVHD) is a major cause of morbidity and mortality, and its management is clinically important. Advances in biological techniques have led to great progress in understanding the complex interactions between the host and the gut microbiota. The gut microbiota clearly modulates the immune response and is associated with the pathogenesis of various disorders. Also in allo-SCT, both preclinical and clinical results indicate that the gut microbiota is closely associated with the development of acute GVHD and transplant outcomes. These results led to the idea that improvement in quantitative and/or qualitative abnormalities of microbiota (dysbiosis) may be a new treatment strategy for acute GVHD. Evaluations of therapies targeting the gut microbiota such as probiotics or fecal microbiota transplantation have just begun. Furthermore, intervention in the gut microbiota with a nutritional approach including prebiotics, postbiotics, and antibiotics selection may also be another promising treatment option for acute GVHD.

Changes in microbial ecology after fecal microbiota transplantation for recurrent C. difficile infection affected by underlying inflammatory bowel disease

BACKGROUND

Gut microbiota play a key role in maintaining homeostasis in the human gut. Alterations in the gut microbial ecosystem predispose to Clostridium difficile infection (CDI) and gut inflammatory disorders such as inflammatory bowel disease (IBD). Fecal microbiota transplantation (FMT) from a healthy donor can restore gut microbial diversity and pathogen colonization resistance; consequently, it is now being investigated for its ability to improve inflammatory gut conditions such as IBD. In this study, we investigated changes in gut microbiota following FMT in 38 patients with CDI with or without underlying IBD.

RESULTS

There was a significant change in gut microbial composition towards the donor microbiota and an overall increase in microbial diversity consistent with previous studies after FMT. FMT was successful in treating CDI using a diverse set of donors, and varying degrees of donor stool engraftment suggesting that donor type and degree of engraftment are not drivers of a successful FMT treatment of CDI. However, patients with underlying IBD experienced an increased number of CDI relapses (during a 24-month follow-up) and a decreased growth of new taxa, as compared to the subjects without IBD. Moreover, the need for IBD therapy did not change following FMT. These results underscore the importance of the existing gut microbial landscape as a decisive factor to successfully treat CDI and potentially for improvement of the underlying pathophysiology in IBD.

CONCLUSIONS

FMT leads to a significant change in microbial diversity in patients with recurrent CDI and complete resolution of symptoms. Stool donor type (related or unrelated) and degree of engraftment are not the key for successful treatment of CDI by FMT. However, CDI patients with IBD have higher proportion of the original community after FMT and lack of improvement of their IBD symptoms and increased episodes of CDI on long-term follow-up.

Novel Indications for Fecal Microbial Transplantation: Update and Review of the Literature

BACKGROUND AND AIMS

Fecal microbial transplantation (FMT) is an established successful treatment modality for recurrent Clostridium difficile infection (CDI). The safety profile and potential therapeutic advantages of FMT for diseases associated with dysbiosis and immune dysfunction have led to many publications, mainly case series, and while many studies and reviews have been published on the use of FMT for inflammatory bowel disease (IBD), its potential use for other disease conditions has not been thoroughly reviewed. The aim of this review was to investigate the evidence surrounding the use of FMT in conditions other than IBD and CDI.

METHODS

A PubMed search was performed using the terms "Fecal microbiota transplantation" OR "FMT" OR "Bacteriotherapy."

RESULTS

A total of 26 articles describing the use of FMT in a variety of both intra-and extraintestinal disease conditions including gastrointestinal, hematologic, neurologic, metabolic, infectious, and autoimmune disorders have been included in this review and have demonstrated some positive results. The studies included were case reports, case series, controlled trials, and cohort studies.

CONCLUSIONS

The findings of these studies demonstrate that FMT, particularly in conditions associated with gastrointestinal dysbiosis, shows promise to provide another effective tool in the therapeutic armament of the practicing physician. FMT was found to be possibly effective in various diseases, mostly associated with enteric dysbiosis or with immune dysfunction. Randomized clinical studies on large populations should be performed to explore the effectiveness of this therapy, and basic research studies should be designed to gain understanding of the mechanisms through which impact these disorders.

Serial Frozen Fecal Microbiota Transplantation in the Treatment of Chronic Intestinal Pseudo-obstruction: A Preliminary Study

Background/Aims

Chronic intestinal pseudo-obstruction (CIPO) is a serious, life-threatening motility disorder that is often related to bacterial overgrowth. Fecal microbiota transplantation (FMT) results in restoration of the normal intestinal microbial community structure. We investigated the efficacy of FMT in the treatment of CIPO patients.

Methods

Nine patients (age 18–53 years) with CIPO were enrolled in this prospective, open-label study. Patients received FMT for 6 consecutive days through nasojejunal (NJ) tubes and were followed up for 8 weeks after treatment. We evaluated the rate of clinical improvement and remission, feeding tolerance of enteral nutrition, and CT imaging scores of intestinal obstructions. Lactulose hydrogen breath tests were performed before FMT and 8 weeks after FMT to evaluate for the presence small intestinal bacterial overgrowth (SIBO).

Results

FMT significantly alleviated bloating symptoms, and symptoms of pain were relieved 2 weeks after FMT. Enteral nutrition administered through a NJ tube after FMT was well-tolerated by 66.7% (6/9) of patients. CT scores of intestinal obstructions were significantly reduced after FMT (P = 0.014). SIBO was eliminated in 71.0% (5/7) of patients.

Conclusions

This pilot study demonstrated the safety of using FMT. FMT may relieve symptoms in selected patients with CIPO. FMT may also improve patient tolerance of enteral nutrition delivered via a NJ tube.

The Gut Microbiota and Autism Spectrum Disorders

Gastrointestinal (GI) symptoms are a common comorbidity in patients with autism spectrum disorder (ASD), but the underlying mechanisms are unknown. Many studies have shown alterations in the composition of the fecal flora and metabolic products of the gut microbiome in patients with ASD. The gut microbiota influences brain development and behaviors through the neuroendocrine, neuroimmune and autonomic nervous systems. In addition, an abnormal gut microbiota is associated with several diseases, such as inflammatory bowel disease (IBD), ASD and mood disorders. Here, we review the bidirectional interactions between the central nervous system and the gastrointestinal tract (brain-gut axis) and the role of the gut microbiota in the central nervous system (CNS) and ASD. Microbiome-mediated therapies might be a safe and effective treatment for ASD.

Fecal microbiota transplantation for refractory Crohn's disease

Approximately one-third of patients with Crohn's disease do not respond to conventional treatments, and some experience significant adverse effects, such as serious infections and lymphoma, and many patients require surgery due to complications. Increasing evidence suggests that specific changes in the composition of gut microbiota, termed as dysbiosis, are a common feature in patients with inflammatory bowel disease (IBD). Dysbiosis can lead to activation of the mucosal immune system, resulting in chronic inflammation and the development of mucosal lesions. Recently, fecal microbiota transplantation, aimed at modifying the composition of gut microbiota to overcome dysbiosis, has become a potential alternative therapeutic option for IBD. Herein, we present a patient with Crohn's colitis in whom biologic therapy failed previously, but clinical remission and endoscopic improvement was achieved after a single fecal microbiota transplantation infusion.

The Host Microbiome Regulates and Maintains Human Health: A Primer and Perspective for Non-Microbiologists

Humans consider themselves discrete autonomous organisms, but recent research is rapidly strengthening the appreciation that associated microorganisms make essential contributions to human health and well being. Each person is inhabited and also surrounded by his/her own signature microbial cloud. A low diversity of microorganisms is associated with a plethora of diseases, including allergy, diabetes, obesity, arthritis, inflammatory bowel diseases, and even neuropsychiatric disorders. Thus, an interaction of microorganisms with the host immune system is required for a healthy body. Exposure to microorganisms from the moment we are born and appropriate microbiome assembly during childhood are essential for establishing an active immune system necessary to prevent disease later in life. Exposure to microorganisms educates the immune system, induces adaptive immunity, and initiates memory B and T cells that are essential to combat various pathogens. The correct microbial-based education of immune cells may be critical in preventing the development of autoimmune diseases and cancer. This review provides a broad overview of the importance of the host microbiome and accumulating knowledge of how it regulates and maintains a healthy human system. Cancer Res; 77(8); 1783-812. ©2017 AACR.

Clostridium difficile Infection and Fecal Microbiota Transplant

Clostridium difficile infection (CDI) is a major source of morbidity and mortality for hospitalized patients. Although most patients have a clinical response to existing antimicrobial therapies, recurrent infection develops in up to 30% of patients. Fecal microbiota transplant is a novel approach to this complex problem, with an efficacy rate of nearly 90% in the setting of multiple recurrent CDI. This review covers the current epidemiology of CDI (including toxigenic and nontoxigenic strains, risk factors for infection, and recurrent infection), methods of diagnosis, existing first-line therapies in CDI, the role of fecal microbiota transplant for multiple recurrent CDIs, and the potential use of fecal microbial transplant for patients with severe or refractory infection.

Enterosalivary nitrate metabolism and the microbiome: Intersection of microbial metabolism, nitric oxide and diet in cardiac and pulmonary vascular health

Recent insights into the bioactivation and signaling actions of inorganic, dietary nitrate and nitrite now suggest a critical role for the microbiome in the development of cardiac and pulmonary vascular diseases. Once thought to be the inert, end-products of endothelial-derived nitric oxide (NO) heme-oxidation, nitrate and nitrite are now considered major sources of exogenous NO that exhibit enhanced vasoactive signaling activity under conditions of hypoxia and stress. The bioavailability of nitrate and nitrite depend on the enzymatic reduction of nitrate to nitrite by a unique set of bacterial nitrate reductase enzymes possessed by specific bacterial populations in the mammalian mouth and gut. The pathogenesis of pulmonary hypertension (PH), obesity, hypertension and CVD are linked to defects in NO signaling, suggesting a role for commensal oral bacteria to shape the development of PH through the formation of nitrite, NO and other bioactive nitrogen oxides. Oral supplementation with inorganic nitrate or nitrate-containing foods exert pleiotropic, beneficial vascular effects in the setting of inflammation, endothelial dysfunction, ischemia-reperfusion injury and in pre-clinical models of PH, while traditional high-nitrate dietary patterns are associated with beneficial outcomes in hypertension, obesity and CVD. These observations highlight the potential of the microbiome in the development of novel nitrate- and nitrite-based therapeutics for PH, CVD and their risk factors.

Efficacy and safety of single fecal microbiota transplantation for Japanese patients with mild to moderately active ulcerative colitis

BACKGROUND

The clinical utility of fecal microbiota transplantation (FMT) in patients with ulcerative colitis (UC) is still controversial. We investigated the efficacy and safety of single FMT for patients with mild to moderately active UC in a Japanese population.

METHODS

Fifty-seven patients were evaluated for eligibility, and 16 patients were excluded. Forty-one patients with UC refractory to standard medical therapy were treated with single FMT by colonoscopic administration. Changes in the fecal microbiota were assessed by 16S ribosomal DNA based terminal restriction fragment length polymorphism analysis.

RESULTS

At 8 weeks after FMT, no patient achieved clinical remission, and 11 of 41 patients (26.8 %) showed clinical response. The full Mayo score and the Mayo clinical score significantly decreased at week 8 [full Mayo score 5.5 ± 2.4 (mean ± standard deviation) at initiation and 4.6 ± 2.2 at week 8, P < 0.004; Mayo clinical score 4.0 ± 2.0 at initiation and 3.0 ± 1.9 at week 8, P < 0.001], but there were no statistically significant effects on the Mayo endoscopic score. No adverse events occurred after FMT or during the follow-up period of 8 weeks. The proportion of Bifidobacterium was significantly higher in the donor feces used for responders than in the donor feces used for nonresponders. The proportion of Lactobacillales and Clostridium cluster IV were significantly higher in the donor feces used for nonresponders.

CONCLUSIONS

Single FMT by colonoscopy was performed safely in all patients, but sufficient clinical efficacy and microbial restoration were not confirmed in patients with mild to moderately active UC.

Reduced microbial diversity in adult survivors of childhood acute lymphoblastic leukemia and microbial associations with increased immune activation

BACKGROUND

Adult survivors of childhood cancers such as acute lymphoblastic leukemia (ALL) have health problems that persist or develop years after cessation of therapy. These late effects include chronic inflammation-related comorbidities such as obesity and type 2 diabetes, but the underlying cause is poorly understood.

RESULTS

We compared the anal microbiota composition of adult survivors of childhood ALL (N = 73) with healthy control subjects (N = 61). We identified an altered community with reduced microbial diversity in cancer survivors, who also exhibit signs of immune dysregulation including increased T cell activation and chronic inflammation. The bacterial community among cancer survivors was enriched for Actinobacteria (e.g. genus Corynebacterium) and depleted of Faecalibacterium, correlating with plasma concentrations of IL-6 and CRP and HLA-DR+CD4+ and HLA-DR+CD8+ T cells, which are established markers of inflammation and immune activation.

CONCLUSIONS

We demonstrated a relationship between microbial dysbiosis and immune dysregulation in adult ALL survivors. These observations suggest that interventions that could restore microbial diversity may ameliorate chronic inflammation and, consequently, development of late effects of childhood cancer survivors.

The gut microbiome and microbial translocation in multiple sclerosis

Individuals with multiple sclerosis (MS) have a distinct intestinal microbial community (microbiota) and increased low-grade translocation of bacteria from the intestines into the circulation. The observed change of intestinal bacteria in MS patients regulate immune functions involved in MS pathogenesis. These functions include: systemic and central nervous system (CNS) immunity (including peripheral regulatory T cell function), the blood-brain barrier (BBB) permeability and CNS-resident cell activity. This review discusses the MS intestinal microbiota implication on MS systemic- and CNS-immunopathology. We introduce the possible contributions of MS low-grade microbial translocation (LG-MT) to the development of MS, and end on a discussion on microbiota therapies for MS patients.

Efficacy of Sterile Fecal Filtrate Transfer for Treating Patients With Clostridium difficile Infection

BACKGROUND & AIMS

Fecal microbiota transplantation (FMT) is a highly effective therapy for recurrent Clostridium difficile infection (CDI). However, transferring undefined living bacteria entails uncontrollable risks for infectious and metabolic or malignant diseases, particularly in immunocompromised patients. We investigated whether sterile fecal filtrates (containing bacterial debris, proteins, antimicrobial compounds, metabolic products, and oligonucleotides/DNA), rather than intact microorganisms, are effective in patients with CDI.

METHODS

We performed a clinical case series to investigate the effects of fecal filtrate transfer (FFT) in 5 patients with symptomatic chronic-relapsing CDI at the Department of Internal Medicine I at the University Hospital Schleswig-Holstein (Kiel, Germany). Patients were followed up for at least 6 months and for up to 33 months. Stool was collected from 5 donors selected by the patients, and fully characterized according to FMT standards. Stool was sterile-filtered to remove small particles and bacteria; the filtrate was transferred to patients in a single administration via nasojejunal tube. Fecal samples were collected from patients before and at 1 week and 6 weeks after FFT. Microbiome, virome, and proteome profiles of donors and patients were compared.

RESULTS

In all 5 patients, FFT restored normal stool habits and eliminated symptoms of CDI for a minimum period of 6 months. Proteome analyses of selected FFT filtrates showed no obvious protein candidates associated with therapeutic efficacy. 16S ribosomal RNA gene sequencing detected diverse bacterial DNA signatures in the filtrates. Analysis of virus-like particles from a filtrate found to reduce symptoms of CDI showed a complex signature of bacteriophages. Bacterial phylogeny and virome profile analyses of fecal samples from recipients indicated longitudinal changes in microbial and viral community structures after FFT.

CONCLUSIONS

A preliminary investigation of 5 patients with CDI shows that transfer of sterile filtrates from donor stool (FFT), rather than fecal microbiota, can be sufficient to restore normal stool habits and eliminate symptoms. This finding indicates that bacterial components, metabolites, or bacteriophages mediate many of the effects of FMT, and that FFT might be an alternative approach, particularly for immunocompromised patients.

Fecal Microbiota Transplantation

Fecal microbiota transplantation (FMT) is the transfer of stool from a healthy donor into the colon of a patient whose disease is a result of an altered microbiome, with the goal of restoring the normal microbiota and thus curing the disease. The most effective and well-studied indication for FMT is recurrent Clostridium difficile infection. At this time, there is insufficient evidence to recommend FMT for other gastrointestinal diseases, but studies are under way. There is also insufficient evidence to recommend FMT for nongastrointestinal diseases at this time. The field is rapidly emerging.

The Gut Microbiota in Inflammatory Bowel Disease

Genes, bacteria, and immunity contribute to the pathogenesis of inflammatory bowel disease. Most genetic risk relates to defective sensing of microbes and their metabolites or defective regulation of the host response to the microbiota. Because the composition of the microbiota shapes the developing immune system and is determined in early life, the prospect of therapeutic manipulation of the microbiota in adulthood after the onset of disease is questionable. However, the microbiota may be a marker of risk and a modifier of disease activity and a contributor to extraintestinal manifestations and associations in some patients with inflammatory bowel disease.

Fecal microbiota transplantation in metabolic syndrome: History, present and future

The history of fecal microbiota transplantation (FMT) dates back even to ancient China. Recently, scientific studies have been looking into FMT as a promising treatment of various diseases, while in the process teaching us about the interaction between the human host and its resident microbial communities. Current research focuses mainly on Clostridium difficile infections, however interest is rising in other areas such as inflammatory bowel disease (IBD) and the metabolic syndrome. With regard to the latter, the intestinal microbiota might be causally related to the progression of insulin resistance and diabetes. FMT in metabolic syndrome has proven to be an intriguing method to study the role of the gut microbiota and open the way to new therapies by dissecting in whom insulin resistance is driven by microbiota. In this article we review the history of FMT, the present evidence on its role in the pathophysiology of metabolic syndrome and its efficacy, limitations and future prospects.

Sampling Strategies for Three-Dimensional Spatial Community Structures in IBD Microbiota Research

Identifying intestinal microbiota is arguably an important task that is performed to determine the pathogenesis of inflammatory bowel diseases (IBD); thus, it is crucial to collect and analyze intestinally-associated microbiota. Analyzing a single niche to categorize individuals does not enable researchers to comprehensively study the spatial variations of the microbiota. Therefore, characterizing the spatial community structures of the inflammatory bowel disease microbiome is critical for advancing our understanding of the inflammatory landscape of IBD. However, at present there is no universally accepted consensus regarding the use of specific sampling strategies in different biogeographic locations. In this review, we discuss the spatial distribution when screening sample collections in IBD microbiota research. Here, we propose a novel model, a three-dimensional spatial community structure, which encompasses the x-, y-, and z-axis distributions; it can be used in some sampling sites, such as feces, colonoscopic biopsy, the mucus gel layer, and oral cavity. On the basis of this spatial model, this article also summarizes various sampling and processing strategies prior to and after DNA extraction and recommends guidelines for practical application in future research.

Carcinogenesis and therapeutics: the microbiota perspective

Cancer arises from the acquisition of multiple genetic and epigenetic changes in host cells over the span of many years, promoting oncogenic traits and carcinogenesis. Most cancers develop following random somatic alterations of key oncogenic genes, which are favoured by a number of risk factors, including lifestyle, diet and inflammation. Importantly, the environment where tumours evolve provides a unique source of signalling cues that affects cancer cell growth, survival, movement and metastasis. Recently, there has been increased interest in how the microbiota, the collection of microorganisms inhabiting the host body surface and cavities, shapes a micro-environment for host cells that can either promote or prevent cancer formation. The microbiota, particularly the intestinal biota, plays a central role in host physiology, and the composition and activity of this consortium of microorganisms is directly influenced by known cancer risk factors such as lifestyle, diet and inflammation. In this REVIEW, we discuss the pro- and anticarcinogenic role of the microbiota, as well as highlighting the therapeutic potential of microorganisms in tumourigenesis. The broad impacts, and, at times, opposing roles of the microbiota in carcinogenesis serve to illustrate the complex and sometimes conflicted relationship between microorganisms and the host-a relationship that could potentially be harnessed for therapeutic benefits.

Genomic Microdiversity of Bifidobacterium pseudocatenulatum Underlying Differential Strain-Level Responses to Dietary Carbohydrate Intervention

The genomic basis of the response to dietary intervention of human gut beneficial bacteria remains elusive, which hinders precise manipulation of the microbiota for human health. After receiving a dietary intervention enriched with nondigestible carbohydrates for 105 days, a genetically obese child with Prader-Willi syndrome lost 18.4% of his body weight and showed significant improvement in his bioclinical parameters. We obtained five isolates (C1, C15, C55, C62, and C95) of one of the most abundantly promoted beneficial species, Bifidobacterium pseudocatenulatum, from a postintervention fecal sample. Intriguingly, these five B. pseudocatenulatum strains showed differential responses during the dietary intervention. Two strains were largely unaffected, while the other three were promoted to different extents by the changes in dietary carbohydrate resources. The differential responses of these strains were consistent with their functional clustering based on the COGs (Clusters of Orthologous Groups), including those involved with the ABC-type sugar transport systems, suggesting that the strain-specific genomic variations may have contributed to the niche adaption. Particularly, B. pseudocatenulatum C15, which had the most diverse types and highest gene copy numbers of carbohydrate-active enzymes targeting plant polysaccharides, had the highest abundance after the dietary intervention. These studies show the importance of understanding genomic diversity of specific members of the gut microbiota if precise nutrition approaches are to be realized.

The manipulation of the gut microbiota via dietary approaches is a promising option for improving human health. Our findings showed differential responses of multiple B. pseudocatenulatum strains isolated from the same habitat to the dietary intervention, as well as strain-specific correlations with bioclinical parameters of the host. The comparative genomics revealed a genome-level microdiversity of related functional genes, which may have contributed to these differences. These results highlight the necessity of understanding strain-level differences if precise manipulation of gut microbiota through dietary approaches is to be realized.

Roles of the intestinal microbiota in pathogen protection

Hundreds of commensal bacterial species inhabit the gastrointestinal tract. This diverse microbial ecosystem plays a crucial role in the prevention and resolution of infectious diseases. In this review we will describe the major mechanisms by which the intestinal microbiota confers protection against infections, focusing on those caused by intestinal bacterial pathogens. These mechanisms include both non-immune- and immune-cell-mediated pathways, notably through bacterial production of inhibitory molecules and nutrient deprivation by the former and innate lymphoid cell-, myeloid cell- or lymphocyte-dependent stimulation by the latter. Finally, we will discuss novel therapeutic approaches based on commensal microbes and their products, which could potentially be used to combat infections.

Fecal microbiota transplantation in patients with slow-transit constipation: A randomized, clinical trial

Fecal microbiota transplantation has been proposed as a therapeutic approach for chronic constipation. This randomized, controlled trial aimed to compare the effects of conventional treatment alone (control) with additional treatment with FMT (intervention) in patients with slow-transit constipation (STC). Adults with STC were randomized to receive intervention or control treatment. The control group received education, behavioral strategies, and oral laxatives. The intervention group was additionally provided 6 days of FMT. The primary endpoint was the clinical cure rate (proportion of patients achieving a mean of ≥ three complete spontaneous bowel movements [CSBMs] per week]. Secondary outcomes and safety parameters were assessed throughout the study. Sixty patients were randomized to either conventional treatment alone (n = 30) or FMT (n = 30) through a nasointestinal tube. There were significant differences between the intervention group and control group in the clinical improvement rate (intention-to-treat [ITT]: 53.3% vs. 20.0%, P = 0.009), clinical cure rate (ITT: 36.7% vs. 13.3%, P = 0.04), mean number of CSBMs per week (ITT: 3.2 ± 1.4 vs. 2.1 ± 1.2, P = 0.001), and the Wexner constipation score (ITT: 8.6 ± 1.5 vs. 12.7 ± 2.5, P < 0.00001). Compared with the control group, the intervention group showed better results in the stool consistency score (ITT: 3.9 vs. 2.4, P < 0.00001) and colonic transit time (ITT: 58.5 vs. 73.6 h, P < 0.00001). The intervention group had more treatment-related adverse events than did the control group (50 vs. 4 cases). FMT was significantly more effective (30% higher cure rate) for treatment of STC than conventional treatment. No serious adverse events were observed.

Management of Clostridium difficile Infection in Inflammatory Bowel Disease: Expert Review from the Clinical Practice Updates Committee of the AGA Institute

The purpose of this expert review is to synthesize the existing evidence on the management of Clostridium difficile infection in patients with underlying inflammatory bowel disease. The evidence reviewed in this article is a summation of relevant scientific publications, expert opinion statements, and current practice guidelines. This review is a summary of expert opinion in the field without a formal systematic review of evidence. Best Practice Advice 1: Clinicians should test patients who present with a flare of underlying inflammatory bowel disease for Clostridium difficile infection. Best Practice Advice 2: Clinicians should screen for recurrent C difficile infection if diarrhea or other symptoms of colitis persist or return after antibiotic treatment for C difficile infection. Best Practice Advice 3: Clinicians should consider treating C difficile infection in inflammatory bowel disease patients with vancomycin instead of metronidazole. Best Practice Advice 4: Clinicians strongly should consider hospitalization for close monitoring and aggressive management for inflammatory bowel disease patients with C difficile infection who have profuse diarrhea, severe abdominal pain, a markedly increased peripheral blood leukocyte count, or other evidence of sepsis. Best Practice Advice 5: Clinicians may postpone escalation of steroids and other immunosuppression agents during acute C difficile infection until therapy for C difficile infection has been initiated. However, the decision to withhold or continue immunosuppression in inflammatory bowel disease patients with C difficile infection should be individualized because there is insufficient existing robust literature on which to develop firm recommendations. Best Practice Advice 6: Clinicians should offer a referral for fecal microbiota transplantation to inflammatory bowel disease patients with recurrent C difficile infection.

Roles for Intestinal Bacteria, Viruses, and Fungi in Pathogenesis of Inflammatory Bowel Diseases and Therapeutic Approaches

Intestinal microbiota are involved in the pathogenesis of Crohn's disease, ulcerative colitis, and pouchitis. We review the mechanisms by which these gut bacteria, fungi, and viruses mediate mucosal homeostasis via their composite genes (metagenome) and metabolic products (metabolome). We explain how alterations to their profiles and functions under conditions of dysbiosis contribute to inflammation and effector immune responses that mediate inflammatory bowel diseases (IBD) in humans and enterocolitis in mice. It could be possible to engineer the intestinal environment by modifying the microbiota community structure or function to treat patients with IBD-either with individual agents, via dietary management, or as adjuncts to immunosuppressive drugs. We summarize the latest information on therapeutic use of fecal microbial transplantation and propose improved strategies to selectively normalize the dysbiotic microbiome in personalized approaches to treatment.

Therapeutic Modulation of Gut Microbiota in Functional Bowel Disorders

Functional bowel disorders (FBDs) are functional gastrointestinal disorders with symptoms attributable to the middle or lower gastrointestinal tract. These include irritable bowel syndrome, functional bloating, functional constipation, functional diarrhea, and unspecified FBD. Increasing evidence has emerged of late that intestinal microbiota is involved in the pathogenesis of FBDs. In this review, the therapeutic benefits and future perspectives of the currently available strategies for modifying the gut microbiota in FBDs are described, focusing primarily on irritable bowel syndrome and functional constipation.

Challenges in fecal donor selection and screening for fecal microbiota transplantation: A review

Fecal microbiota transplantation is best understood as an effective and inexpensive therapy for recurrent Clostridium difficile infection but fecal donor selection and screening should be periodically revised. Here, we review current recommendations for selection and screening of fecal donors for fecal microbiota transplantation. We recommend considering diabetes mellitus, prior cardiovascular events, and clinical healthcare exposure as fecal donor exclusion criteria until more is known about the association of these conditions with the human gut microbiome. We review the non-bacterial members of the human gut microbiome, associations of the gut microbiome with colorectal malignancies, the human gut resistome and how these may impact future donor screening recommendations. Collaboration between clinicians, clinical laboratory scientists, industry and regulatory agencies will be critically important for continued improvement in donor selection and screening.

Profiling Living Bacteria Informs Preparation of Fecal Microbiota Transplantations

Fecal microbiota transplantation is a compelling treatment for recurrent Clostridium difficile infections, with potential applications against other diseases associated with changes in gut microbiota. But variability in fecal bacterial communities—believed to be the therapeutic agent—can complicate or undermine treatment efficacy. To understand the effects of transplant preparation methods on living fecal microbial communities, we applied a DNA-sequencing method (PMA-seq) that uses propidium monoazide (PMA) to differentiate between living and dead fecal microbes, and we created an analysis pipeline to identify individual bacteria that change in abundance between samples. We found that oxygen exposure degraded fecal bacterial communities, whereas freeze-thaw cycles and lag time between donor defecation and transplant preparation had much smaller effects. Notably, the abundance of Faecalibacterium prausnitzii—an anti-inflammatory commensal bacterium whose absence is linked to inflammatory bowel disease—decreased with oxygen exposure. Our results indicate that some current practices for preparing microbiota transplant material adversely affect living fecal microbial content and highlight PMA-seq as a valuable tool to inform best practices and evaluate the suitability of clinical fecal material.

Factors shaping the composition of the cutaneous microbiota

From birth, we are constantly exposed to bacteria, fungi and viruses, some of which are capable of transiently or permanently inhabiting our different body parts as our microbiota. The majority of our microbial interactions occur during and after birth, and several different factors, including age, sex, genetic constitution, environmental conditions and lifestyle, have been suggested to shape the composition of this microbial community. Propionibacterium acnes is one of the most dominant lipophilic microbes of the postadolescent, sebum-rich human skin regions. Currently, the role of this bacterium in the pathogenesis of the most common inflammatory skin disease, acne vulgaris, is a topic of intense scientific debate. Recent results suggest that Westernization strongly increases the dominance of the Propionibacterium genus in human skin compared with natural populations living more traditional lifestyles. According to the disappearing microbiota hypothesis proposed by Martin Blaser, such alterations in the composition of our microbiota are the possible consequences of socioeconomic and lifestyle changes occurring after the industrial revolution. Evanescence of species that are important elements of the human ecosystem might lead to the overgrowth and subsequent dominance of others because of the lack of ecological competition. Such changes can disturb the fine-tuned balance of the human body and, accordingly, our microbes developed through a long co-evolutionary process. These processes might lead to the transformation of a seemingly harmless species into an opportunistic pathogen through bacterial dysbiosis. This might have happened in the case of P. acnes in acne pathogenesis.

Laboratory Testing of Donors and Stool Samples for Fecal Microbiota Transplantation for Recurrent Clostridium difficile Infection

Fecal microbiota transplantation is an efficacious and inexpensive therapy for recurrent Clostridium difficile infection, yet its safety is thought to depend on appropriate fecal donor screening. FDA guidance for regulation of this procedure is in flux, but screening and manufacture of fecal material from asymptomatic donors present many challenges to clinical laboratories. This minireview summarizes FDA regulatory changes, principles of donor selection, and recommended laboratory screening practices for fecal microbiota transplantation.

Consensus report: faecal microbiota transfer - clinical applications and procedures

BACKGROUND

Faecal microbiota transplantation or transfer (FMT) aims at replacing or reinforcing the gut microbiota of a patient with the microbiota from a healthy donor. Not many controlled or randomised studies have been published evaluating the use of FMT for other diseases than Clostridium difficile infection, making it difficult for clinicians to decide on a suitable indication.

AIM

To provide an expert consensus on current clinical indications, applications and methodological aspects of FMT.

METHODS

Well-acknowledged experts from various countries in Europe have contributed to this article. After literature review, consensus has been achieved by repetitive circulation of the statements and the full manuscript among all authors with intermittent adaptation to comments (using a modified Delphi process). Levels of evidence and agreement were rated according to the GRADE system. Consensus was defined a priori as agreement by at least 75% of the authors.

RESULTS

Key recommendations include the use of FMT in recurrent C. difficile infection characterised by at least two previous standard treatments without persistent cure, as well as its consideration in severe and severe-complicated C. difficile infection as an alternative to total colectomy in case of early failure of antimicrobial therapy. FMT in inflammatory bowel diseases (IBD), irritable bowel syndrome (IBS) and metabolic syndrome should only be performed in research settings.

CONCLUSIONS

Faecal microbiota transplantation or transfer is a promising treatment for a variety of diseases in which the intestinal microbiota is disturbed. For indications other than C. difficile infection, more evidence is needed before more concrete recommendations can be made.