Long-term changes of bacterial and viral compositions in the intestine of a recovered Clostridium difficile patient after fecal microbiota transplantation

Engraftment of essential functions through multiple fecal microbiota transplants in chronic antibiotic-resistant pouchitis-a case study using metatranscriptomics

BACKGROUND

Ileal pouch-anal anastomosis (IPAA) is the standard of care after total proctocolectomy for ulcerative colitis (UC). Around 50% of patients will experience pouchitis, an idiopathic inflammatory condition. Antibiotics are the backbone of treatment of pouchitis; however, antibiotic-resistant pouchitis develops in 5-10% of those patients. It has been shown that fecal microbiota transplantation (FMT) is an effective treatment for UC, but results for FMT antibiotic-resistant pouchitis are inconsistent.

METHODS

To uncover which metabolic activities were transferred to the recipients during FMT and helped the remission, we performed a longitudinal case study of the gut metatranscriptomes from three patients and their donors. The patients were treated by two to three FMTs, and stool samples were analyzed for up to 140 days.

RESULTS

Reduced expression in pouchitis patients compared to healthy donors was observed for genes involved in biosynthesis of amino acids, cofactors, and B vitamins. An independent metatranscriptome dataset of UC patients showed a similar result. Other functions including biosynthesis of butyrate, metabolism of bile acids, and tryptophan were also much lower expressed in pouchitis. After FMT, these activities transiently increased, and the overall metatranscriptome profiles closely mirrored those of the respective donors with notable fluctuations during the subsequent weeks. The levels of the clinical marker fecal calprotectin were concordant with the metatranscriptome data. Faecalibacterium prausnitzii represented the most active species contributing to butyrate synthesis via the acetyl-CoA pathway. Remission occurred after the last FMT in all patients and was characterized by a microbiota activity profile distinct from donors in two of the patients.

CONCLUSIONS

Our study demonstrates the clear but short-lived activity engraftment of donor microbiota, particularly the butyrate biosynthesis after each FMT. The data suggest that FMT triggers shifts in the activity of patient microbiota towards health which need to be repeated to reach critical thresholds. As a case study, these insights warrant cautious interpretation, and validation in larger cohorts is necessary for generalized applications. In the long run, probiotics with high taxonomic diversity consisting of well characterized strains could replace FMT to avoid the costly screening of donors and the risk of transferring unwanted genetic material. Video Abstract.

Recipient-independent, high-accuracy FMT-response prediction and optimization in mice and humans

BACKGROUND

Some microbiota compositions are associated with negative outcomes, including among others, obesity, allergies, and the failure to respond to treatment. Microbiota manipulation or supplementation can restore a community associated with a healthy condition. Such interventions are typically probiotics or fecal microbiota transplantation (FMT). FMT donor selection is currently based on donor phenotype, rather than the anticipated microbiota composition in the recipient and associated health benefits. However, the donor and post-transplant recipient conditions differ drastically. We here propose an algorithm to identify ideal donors and predict the expected outcome of FMT based on donor microbiome alone. We also demonstrate how to optimize FMT for different required outcomes.

RESULTS

We show, using multiple microbiome properties, that donor and post-transplant recipient microbiota differ widely and propose a tool to predict the recipient post-transplant condition (engraftment success and clinical outcome), using only the donors' microbiome and, when available, demographics for transplantations from humans to either mice or other humans (with or without antibiotic pre-treatment). We validated the predictor using a de novo FMT experiment highlighting the possibility of choosing transplants that optimize an array of required goals. We then extend the method to characterize a best-planned transplant (bacterial cocktail) by combining the predictor and a generative genetic algorithm (GA). We further show that a limited number of taxa is enough for an FMT to produce a desired microbiome or phenotype.

CONCLUSIONS

Off-the-shelf FMT requires recipient-independent optimized FMT selection. Such a transplant can be from an optimal donor or from a cultured set of microbes. We have here shown the feasibility of both types of manipulations in mouse and human recipients. Video Abstract.

Returning to Nature for the Next Generation of Antimicrobial Therapeutics

Antibiotics found in and inspired by nature are life-saving cures for bacterial infections and have enabled modern medicine. However, the rise in resistance necessitates the discovery and development of novel antibiotics and alternative treatment strategies to prevent the return to a pre-antibiotic era. Once again, nature can serve as a source for new therapies in the form of natural product antibiotics and microbiota-based therapies. Screening of soil bacteria, particularly actinomycetes, identified most of the antibiotics used in the clinic today, but the rediscovery of existing molecules prompted a shift away from natural product discovery. Next-generation sequencing technologies and bioinformatics advances have revealed the untapped metabolic potential harbored within the genomes of environmental microbes. In this review, we first highlight current strategies for mining this untapped chemical space, including approaches to activate silent biosynthetic gene clusters and in situ culturing methods. Next, we describe how using live microbes in microbiota-based therapies can simultaneously leverage many of the diverse antimicrobial mechanisms found in nature to treat disease and the impressive efficacy of fecal microbiome transplantation and bacterial consortia on infection. Nature-provided antibiotics are some of the most important drugs in human history, and new technologies and approaches show that nature will continue to offer valuable inspiration for the next generation of antibacterial therapeutics.

Proton pump inhibitors may enhance the risk of digestive diseases by regulating intestinal microbiota

Proton pump inhibitors (PPIs) are the most used acid-inhibitory drugs, with a wide range of applications in the treatment of various digestive diseases. However, recently, there has been a growing number of digestive complications linked to PPIs, and several studies have indicated that the intestinal flora play an important role in these complications. Therefore, developing a greater understanding of the role of the gut microbiota in PPI-related digestive diseases is essential. Here, we summarize the current research on the correlation between PPI-related digestive disorders and intestinal flora and establish the altered strains and possible pathogenic mechanisms of the different diseases. We aimed to provide a theoretical basis and reference for the future treatment and prevention of PPI-related digestive complications based on the regulation of the intestinal microbiota.

The human gut virome: composition, colonization, interactions, and impacts on human health

The gut virome is an incredibly complex part of the gut ecosystem. Gut viruses play a role in many disease states, but it is unknown to what extent the gut virome impacts everyday human health. New experimental and bioinformatic approaches are required to address this knowledge gap. Gut virome colonization begins at birth and is considered unique and stable in adulthood. The stable virome is highly specific to each individual and is modulated by varying factors such as age, diet, disease state, and use of antibiotics. The gut virome primarily comprises bacteriophages, predominantly order Crassvirales, also referred to as crAss-like phages, in industrialized populations and other Caudoviricetes (formerly Caudovirales). The stability of the virome's regular constituents is disrupted by disease. Transferring the fecal microbiome, including its viruses, from a healthy individual can restore the functionality of the gut. It can alleviate symptoms of chronic illnesses such as colitis caused by Clostridiodes difficile. Investigation of the virome is a relatively novel field, with new genetic sequences being published at an increasing rate. A large percentage of unknown sequences, termed 'viral dark matter', is one of the significant challenges facing virologists and bioinformaticians. To address this challenge, strategies include mining publicly available viral datasets, untargeted metagenomic approaches, and utilizing cutting-edge bioinformatic tools to quantify and classify viral species. Here, we review the literature surrounding the gut virome, its establishment, its impact on human health, the methods used to investigate it, and the viral dark matter veiling our understanding of the gut virome.

The Mechanism of Important Components in Canine Fecal Microbiota Transplantation

Fecal microbiota transplantation (FMT) is a potential treatment for many intestinal diseases. In dogs, FMT has been shown to have positive regulation effects in treating Clostridioides difficile infection (CDI), inflammatory bowel disease (IBD), canine parvovirus (CPV) enteritis, acute diarrhea (AD), and acute hemorrhagic diarrhea syndrome (AHDS). FMT involves transplanting the functional components of a donor's feces into the gastrointestinal tract of the recipient. The effective components of FMT not only include commensal bacteria, but also include viruses, fungi, bacterial metabolites, and immunoglobulin A (IgA) from the donor feces. By affecting microbiota and regulating host immunity, these components can help the recipient to restore their microbial community, improve their intestinal barrier, and induce anti-inflammation in their intestines, thereby affecting the development of diseases. In addition to the above components, mucin proteins and intestinal epithelial cells (IECs) may be functional ingredients in FMT as well. In addition to the abovementioned indications, FMT is also thought to be useful in treating some other diseases in dogs. Consequently, when preparing FMT fecal material, it is important to preserve the functional components involved. Meanwhile, appropriate fecal material delivery methods should be chosen according to the mechanisms these components act by in FMT.

Microbiosis in lung allotransplantation and xenotransplantation: State of the art and future perspective

The respiratory tract is known to harbor a microbial community including bacteria, viruses, and fungi. New techniques contribute enormously to the identification of unknown or culture-independent species and reveal the interaction of the community with the host immune system. The existing respiratory microbiome and substantial equilibrium of the transplanted microbiome from donor lung grafts provide an extreme bloom of dynamic changes in the microenvironment in lung transplantation (LT) recipients. Dysbiosis in grafts are not only related to the modified microbial components but also involve the kinetics of the host-graft "talk," which signifies the destination of graft allograft injury, acute rejection, infection, and chronic allograft dysfunction development in short- and long-term survival. Microbiome-derived factors may contribute to lung xenograft survival when using genetically multimodified pig-derived organs. Here, we review the most advanced knowledge of the dynamics and resilience of microbial communities in transplanted lungs with various pretransplant indications. Conceptual and analytical points of view have been illustrated along the time series, gaining insight into the microbiome and lung grafts. Future endeavors on precise tools, sophisticated models, and novel targeted regimens are needed to improve the long-term survival in these patients.

Rehabilitation of a misbehaving microbiome: phages for the remodeling of bacterial composition and function

The human gut microbiota is considered an adjunct metabolic organ owing to its health impact. Recent studies have shown correlations between gut phage composition and host health. Whereas phage therapy has popularized virulent phages as antimicrobials, both virulent and temperate phages have a natural ecological relationship with their cognate bacteria. Characterization of this evolutionary coadaptation has led to other emergent therapeutic phage applications that do not necessarily rely on bacterial eradication or target pathogens. Here, we present an overview of the tripartite relationship between phages, bacteria, and the mammalian host, and highlight applications of the wildtype and genetically engineered phage for gut microbiome remodeling. In light of new and varied strategies, we propose to categorize phage applications aiming to modulate bacterial composition or function as “phage rehabilitation.” By delineating phage rehab from phage therapy, we believe it will enable greater nuance and understanding of these new phage-based technologies.

Encapsulated Fecal Microbiota Transplantation: Development, Efficacy, and Clinical Application

Fecal microbiota transplantation (FMT) has been established as a highly restorative therapeutic approach for treating recurrent Clostridioides difficile infection (rCDI). Recently, the use of capsule-based fecal microbiota transplantation (cFMT) has been shown to be a clinically effective approach to restore intestinal microbiota composition. This convenient, oral delivery provides an easy route of administration and a newfound flexibility for clinicians and patients. In this review, we discuss the development of cFMT, paying particular attention to lyophilized cFMT products. We review the available published clinical studies comparing cFMT with lower endoscopic FMT (eFMT) or placebo. We further discuss the pharmacokinetics of FMT, which should be understood in a framework of microbial ecology that considers the complex and dynamic interactions of gut microbiota with host factors and other microorganisms. Promisingly, the results of multiple trials investigating cFMT vs. eFMT in rCDI show cFMT to be as effective as eFMT at preventing rCDI. However, its efficacy in non-rCDI conditions, including obesity and metabolic syndrome, inflammatory bowel disease, HIV, and neurologic conditions, is less clear and more research is needed in these areas. Standardization of formulation, dose, and timing of administration to ensure optimal microbiota engraftment and clinical response is also a challenge to be addressed. Overall, cFMT is a practical method for fecal microbiota transplantation, with similar efficacy to eFMT in the resolution of rCDI, that holds therapeutic potential in a variety of other diseases.

Gut bacteriophage dynamics during fecal microbial transplantation in subjects with metabolic syndrome

Metabolic Syndrome (MetS) is a growing public health concern worldwide. Individuals with MetS have an increased risk for cardiovascular (CV) disease and type 2 diabetes (T2D). These diseases - in part preventable with the treatment of MetS - increase the chances of premature death and pose a great economic burden to health systems. A healthy gut microbiota is associated with a reduction in MetS, T2D, and CV disease. Treatment of MetS with fecal microbiota transplantation (FMT) can be effective, however, its success rate is intermediate and difficult to predict. Because bacteriophages significantly affect the microbiota membership and function, the aim of this pilot study was to explore the dynamics of the gut bacteriophage community after FMT in MetS subjects. We performed a longitudinal study of stool bacteriophages from healthy donors and MetS subjects before and after FMT treatment. Subjects were assigned to either a control group (self-stool transplant, n = 3) or a treatment group (healthy-donor-stool transplant; n-recipients = 6, n-donors = 5). Stool samples were collected over an 18-week period and bacteriophage-like particles were purified and sequenced. We found that FMT from healthy donors significantly alters the gut bacteriophage community. Subjects with better clinical outcome clustered closer to the heathy donor group, suggesting that throughout the treatment, their bacteriophage community was more similar to healthy donors. Finally, we identified bacteriophage groups that could explain these differences and we examined their prevalence in individuals from a larger cohort of MetS FMT trial.Trial information- http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2705; NTR 2705.

Identification and Antibiotic Profiling of Wohlfahrtiimonas chitiniclastica, an Underestimated Human Pathogen

In the past 12 years, several case reports have clearly demonstrated that Wohlfahrtiimonas chitiniclastica is capable of causing sepsis and bacteremia in humans. However, since most clinicians are not familiar with this species, little is known about its pathogenicity and treatment options while it is as rare but underestimated human pathogen. Therefore, a larger strain collection is required so that methods can be identified that are most suitable to obtain rapid and reliable identification. Moreover, the antimicrobial resistance profile needs to be elucidated in order to explore possible treatment options. Over a period of 6 years, we therefore have collected a total of 14 W. chitiniclastica isolates in routine diagnostics, which now served as the basis for a comprehensive characterization with respect to identification and antibiotic profiling. We compared the accuracy and convenience of several identification techniques in which MALDI-TOF MS and sequencing of the 16S rRNA gene have proven to be suitable for identification of W. chitiniclastica. In addition, whole genome sequencing (WGS)-based digital DNA-DNA hybridization (dDDH) was used as a reference method for strain identification, and surprised with the detection of a novel W. chitiniclastica subspecies. A combination of in silico and in vitro analyses revealed a first insight into the antimicrobial resistance profile and the molecular basis of antimicrobial resistance. Based on our findings, trimethoprim/sulfamethoxazole, levofloxacin, and cephalosporins (e.g., ceftazidime) may be the best antibiotics to use in order to treat infections caused by W. chitiniclastica, while resistance to fosfomycin, amikacin and tobramycin is observed.

Long-Term Follow-Up Results of Fecal Microbiota Transplantation for Irritable Bowel Syndrome: A Single-Center, Retrospective Study

Objective: This study aimed to investigate the long-term efficacy of fecal microbiota transplantation (FMT) in patients with irritable bowel syndrome (IBS).

Study Methods: In this single-center long-term follow-up study, FMT treatment was administered to patients with moderate to severe IBS (IBS severity scoring system (IBS-SSS) > 175). After 1 year of treatment, it was decided whether to repeat FMT based on IBS-SSS score (IBS-SSS > 175). Baseline characteristics before and after FMT and questionnaires were completed at 1, 3, 6, 12, 24, 36, 48, and 60 months after FMT. The study outcomes included treatment efficacy rates, change of IBS-SSS, IBS-specific quality of life and fatigue, effect on stool frequency, Bristol Stool Scale for IBS-C and IBS-D, and side effects.

Results: A total of 227 patients (47.58% IBS-C, 39.21% IBS-D, and 13.22% IBS-M) were recruited (142 females and 85 males with a mean age of 41.89 ± 13.57 years). The efficacy rates were 108 (51.92%), 147 (74.62%), 125 (74.41 %), 88 (71.54%), 78 (75.00%), 65 (73.03%), 45 (61.64%), and 37 (62.71%) at different follow-up time points. The total IBS-SSS score was 321.37 ± 73.89 before FMT, which significantly decreased after 1 month. The IBS-specific quality of life (IBS-QoL) score was 40.24 ± 11.34 before FMT, increased gradually, and was significantly higher at 3 months compared to before FMT. The total Fatigue Assessment Scale (FAS) score was 47 ± 8.64 before FMT and was significantly lower at 3 months. During follow-up, 89 (39.21%) side effects occurred that were alleviated by symptomatic treatment, and no serious adverse events were detected.

Conclusion: Based on 60 months of long-term follow-up, the safety and efficacy of FMT for IBS was established. However, as the treatment effect declines over time, periodic and repetitive FMT is required for a sustained effect.

Recipient factors in faecal microbiota transplantation: one stool does not fit all

Faecal microbiota transplantation (FMT) is a promising therapy for chronic diseases associated with gut microbiota alterations. FMT cures 90% of recurrent Clostridioides difficile infections. However, in complex diseases, such as inflammatory bowel disease, irritable bowel syndrome and metabolic syndrome, its efficacy remains variable. It is accepted that donor selection and sample administration are key determinants of FMT success, yet little is known about the recipient factors that affect it. In this Perspective, we discuss the effects of recipient parameters, such as genetics, immunity, microbiota and lifestyle, on donor microbiota engraftment and clinical efficacy. Emerging evidence supports the possibility that controlling inflammation in the recipient intestine might facilitate engraftment by reducing host immune system pressure on the newly transferred microbiota. Deciphering FMT engraftment rules and developing novel therapeutic strategies are priorities to alleviate the burden of chronic diseases associated with an altered gut microbiota such as inflammatory bowel disease.

Updating changes in human gut microbial communities associated with Clostridioides difficile infection

Clostridioides difficile is the causative agent of antibiotic-associated diarrhea, a worldwide public health problem. Different factors can promote the progression of C. difficile infection (CDI), mainly altered intestinal microbiota composition. Microbial species belonging to different domains (i.e., bacteria, archaea, eukaryotes, and even viruses) are synergistically and antagonistically associated with CDI. This review was aimed at updating changes regarding CDI-related human microbiota composition using recent data and an integral approach that included the different microorganism domains. The three domains of life contribute to intestinal microbiota homeostasis at different levels in which relationships among microorganisms could explain the wide range of clinical manifestations. A holistic understanding of intestinal ecosystem functioning will facilitate identifying new predictive factors for infection and developing better treatment and new diagnostic tools, thereby reducing this disease's morbidity and mortality.

Faecal microbiota transplantation for Clostridioides difficile: mechanisms and pharmacology

Faecal microbiota transplantation (FMT) has emerged as a remarkably successful treatment for recurrent Clostridioides difficile infection that cannot be cured with antibiotics alone. Understanding the complex biology and pathogenesis of C. difficile infection, which we discuss in this Perspective, is essential for understanding the potential mechanisms by which FMT cures this disease. Although FMT has already entered clinical practice, different microbiota-based products are currently in clinical trials and are vying for regulatory approval. However, all these therapeutics belong to an entirely new class of agents that require the development of a new branch of pharmacology. Characterization of microbiota therapeutics uses novel and rapidly evolving technologies and requires incorporation of microbial ecology concepts. Here, we consider FMT within a pharmacological framework, including its essential elements: formulation, pharmacokinetics and pharmacodynamics. From this viewpoint, multiple gaps in knowledge become apparent, identifying areas that require systematic research. This knowledge is needed to help clinical providers use microbiota therapeutics appropriately and to facilitate development of next-generation microbiota products with improved safety and efficacy. The discussion here is limited to FMT as a representative of microbiota therapeutics and recurrent C. difficile as the indication; however, consideration of the intrinsic basic principles is relevant to this entire class of microbiota-based therapeutics.

Fecal Microbiota Transplant in a Patient Infected with Multidrug-Resistant Bacteria: A Case Report

Introduction

There has been a growing interest in fecal microbiota transplantation (FMT) as a way to manipulate gut microbiota, with potential benefit in patients infected with multidrug-resistant (MDR) bacteria.

Case Presentation

We present the case of an 87-year-old male with recurrent ascending cholangitis due to biliary atony and impaired biliary drainage after multiple biliary sphincterotomies and two papillary balloon dilations. In this context, a choledochoduodenostomy was performed, but the patient kept on having repeated episodes of acute cholangitis, resulting in multiple hospitalizations, every other week, with need of multiple broad-spectrum antibiotic courses, which led to bacteremias with MDR microorganisms. Several therapeutic strategies such as prophylactic antibiotics (including rifaximin), pre- and probiotics, prokinetics, and ursodeoxycholic acid were unsuccessfully attempted. After multidisciplinary case discussion, an FMT was proposed, with the aim of manipulating gut microbiota and decreasing MDR bacteremias. We first performed FMT via colonoscopy in September 2018, after which the patient still had 3 more hospitalizations for acute cholangitis, but isolated bacteria in blood cultures were resistant only to amoxicillin and clavulanic acid. Considering this apparent change in the microbial resistance profile, we performed a second FMT in January 2019 via the upper gastrointestinal route. During the next 4 months, the patient remained well. In April 2019, the patient relapsed again with three more episodes of cholangitis, for which we repeated the FMT via upper gastrointestinal endoscopy. No readmissions were observed during the next 4 months. All three FMTs were performed without complications.

Discussion and Conclusion

FMT seems to be a safe procedure and was effective in decreasing hospital admissions and changing the profile of MDR bacteria previously isolated from blood cultures.

Cultivation and Genomics Prove Long-Term Colonization of Donor's Bifidobacteria in Recurrent Clostridioides difficile Patients Treated With Fecal Microbiota Transplantation

Fecal microbiota transplantation (FMT) is an effective treatment for recurrent Clostridioides difficile infection (rCDI) and it’s also considered for treating other indications. Metagenomic studies have indicated that commensal donor bacteria may colonize FMT recipients, but cultivation has not been employed to verify strain-level colonization. We combined molecular profiling of Bifidobacterium populations with cultivation, molecular typing, and whole genome sequencing (WGS) to isolate and identify strains that were transferred from donors to recipients. Several Bifidobacterium strains from two donors were recovered from 13 recipients during the 1-year follow-up period after FMT. The strain identities were confirmed by WGS and comparative genomics. Our results show that specific donor-derived bifidobacteria can colonize rCDI patients for at least 1 year, and thus FMT may have long-term consequences for the recipient‘s microbiota and health. Conceptually, we demonstrate that FMT trials combined with microbial profiling can be used as a platform for discovering and isolating commensal strains with proven colonization capacity for potential therapeutic use.

Phages Needed against Resistant Bacteria

Phages have been known for more than 100 years. They have been applied to numerous infectious diseases and have proved to be effective in many cases. However, they have been neglected due to the era of antibiotics. With the increase of antibiotic-resistant microorganisms, we need additional therapies. Whether or not phages can fulfill this expectation needs to be verified and tested according to the state-of-the-art of international regulations. These regulations fail, however, with respect to GMP production of phages. Phages are biologicals, not chemical compounds, which cannot be produced under GMP regulations. This needs to be urgently changed to allow progress to determine how phages can enter routine clinical settings.

Allogenic Fecal Microbiota Transplantation in Patients With Nonalcoholic Fatty Liver Disease Improves Abnormal Small Intestinal Permeability: A Randomized Control Trial

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is an obesity-related disorder that is rapidly increasing in incidence and is considered the hepatic manifestation of the metabolic syndrome. The gut microbiome plays a role in metabolism and maintaining gut barrier integrity. Studies have found differences in the microbiota between NAFLD and healthy patients and increased intestinal permeability in patients with NAFLD. Fecal microbiota transplantation (FMT) can be used to alter the gut microbiome. It was hypothesized that an FMT from a thin and healthy donor given to patients with NAFLD would improve insulin resistance (IR), hepatic proton density fat fraction (PDFF), and intestinal permeability.

METHODS

Twenty-one patients with NAFLD were recruited and randomized in a ratio of 3:1 to either an allogenic (n = 15) or an autologous (n = 6) FMT delivered by using an endoscope to the distal duodenum. IR was calculated by HOMA-IR, hepatic PDFF was measured by MRI, and intestinal permeability was tested using the lactulose:mannitol urine test. Additional markers of metabolic syndrome and the gut microbiota were examined. Patient visits occurred at baseline, 2, 6 weeks, and 6 months post-FMT.

RESULTS

There were no significant changes in HOMA-IR or hepatic PDFF in patients who received the allogenic or autologous FMT. Allogenic FMT patients with elevated small intestinal permeability (>0.025 lactulose:mannitol, n = 7) at baseline had a significant reduction 6 weeks after allogenic FMT.

DISCUSSION

FMT did not improve IR as measured by HOMA-IR or hepatic PDFF but did have the potential to reduce small intestinal permeability in patients with NAFLD.

Lessons Learned from Faecal Microbiota Transplantation in Cirrhosis

Purpose of Review

We examine recent developments in the treatment of cirrhosis by gut microbiome manipulation specifically focusing on the phase 1 safety and feasibility trials of faecal microbiota transplantation (FMT). We interrogate the published data so far on its feasibility, safety and efficacy.

Recent Findings

A large number of trials have demonstrated the efficacy of FMT in treating recurrent Clostridium difficile infection which is now considered standard of care. In cirrhosis, FMT is still being evaluated and there are a number of clinical trials underway. There are two phase 1 pilot safety studies that have been published with promising findings. However, the importance of rigorously testing donor stool for the presence of multi-drug resistant species has been highlighted and lessons have been learned.

Summary

For those patients with cirrhosis, replacing an unhealthy gut microbiome with a healthy one offers a promising antibiotic-free treatment that may reduce bacterial translocation and endotoxemia.

Air Microbiome and Pollution: Composition and Potential Effects on Human Health, Including SARS Coronavirus Infection

Polluted air poses a significant threat to human health. Exposure to particulate matter (PM) and harmful gases contributes to cardiovascular and respiratory diseases, including allergies and obstructive lung disease. Air pollution may also be linked to cancer and reduced life expectancy. Uptake of PM has been shown to cause pathological changes in the intestinal microbiota in mice and humans. Less is known about the effects of pollution-associated microbiota on human health. Several recent studies described the microbiomes of urban and rural air samples, of the stratosphere and sand particles, which can be transported over long distances, as well as the air of indoor environments. Here, we summarize the current knowledge on airborne bacterial, viral, and fungal communities and discuss their potential consequences on human health. The current data suggest that bacterial pathogens are typically too sparse and short-lived in air to pose a significant risk for infecting healthy people. However, airborne fungal spores may exacerbate allergies and asthma. Little information is available on viruses including phages, and future studies are likely to detect known and novel viruses with a yet unknown impact on human health. Furthermore, varying experimental protocols have been employed in the recent microbiome and virome studies. Therefore, standardized methodologies will be required to allow for better comparisons between studies. Air pollution has been linked to more severe outcomes of SARS (severe acute respiratory syndrome) coronavirus (SARS-CoV) infections. This may have contributed to severe SARS-CoV-2 outbreaks, especially those in China, Northern Italy, Iran, and New York City.

Limited changes in the fecal microbiome composition of laying hens after oral inoculation with wild duck feces

Interspecies transmission of fecal microbiota can serve as an indicator for (indirect) contact between domestic and wild animals to assess risks of pathogen transmission, e.g., avian influenza. Here, we investigated whether oral inoculation of laying hens with feces of wild ducks (mallards, Anas platyrhynchos) resulted in a hen fecal microbiome that was detectably altered on community parameters or relative abundances of individual genera. To distinguish between effects of the duck inoculum and effects of the inoculation procedure, we compared the fecal microbiomes of adult laying hens resulting from 3 treatments: inoculation with wild duck feces (duck), inoculation with chicken feces (auto), and a negative control group with no treatment. We collected cloacal swabs from 7 hens per treatment before (day 0), and 2 and 7 D after inoculation, and performed 16S rRNA amplicon sequencing. No distinguishable effect of inoculation with duck feces on microbiome community (alpha and beta diversity) was found compared to auto or control treatments. At the individual taxonomic level, the relative abundance of the genus Alistipes (phylum Bacteroidetes) was significantly higher in the inoculated treatments (auto and duck) compared to the control 2 D after inoculation. Seven days after inoculation, the relative abundance of Alistipes had increased in the control and no effect was found anymore across treatments. These effects might be explained by the perturbation of the hen's microbiome caused by the inoculation procedure itself, or by intrinsic temporal variation in the hen's microbiome. This experiment shows that a single inoculation of fecal microbiota from duck feces to laying hens did not cause a measurable alteration of the gut microbiome community. Furthermore, the temporary change in relative abundance forAlistipes could not be attributed to the duck feces inoculation. These outcomes suggest that the fecal microbiome of adult laying hens may not be a useful indicator for detection of single oral exposure to wild duck feces.

Recent advances in modulating the microbiome

We are in the midst of “the microbiome revolution”—not a day goes by without some new revelation on the potential role of the gut microbiome in some disease or disorder. From an ever-increasing recognition of the many roles of the gut microbiome in health and disease comes the expectation that its modulation could treat or prevent these very same diseases. A variety of interventions could, at least in theory, be employed to alter the composition or functional capacity of the microbiome, ranging from diet to fecal microbiota transplantation (FMT). For some, such as antibiotics, prebiotics, and probiotics, an extensive, albeit far from consistent, literature already exists; for others, such as other dietary supplements and FMT, high-quality clinical studies are still relatively few in number. Not surprisingly, researchers have turned to the microbiome itself as a source for new entities that could be used therapeutically to manipulate the microbiome; for example, some probiotic strains currently in use were sourced from the gastrointestinal tract of healthy humans. From all of the extant studies of interventions targeted at the gut microbiome, a number of important themes have emerged. First, with relatively few exceptions, we are still a long way from a precise definition of the role of the gut microbiome in many of the diseases where a disturbed microbiome has been described—association does not prove causation. Second, while animal models can provide fascinating insights into microbiota–host interactions, they rarely recapitulate the complete human phenotype. Third, studies of several interventions have been difficult to interpret because of variations in study population, test product, and outcome measures, not to mention limitations in study design. The goal of microbiome modulation is a laudable one, but we need to define our targets, refine our interventions, and agree on outcomes.

Chloroviruses

Chloroviruses are large dsDNA, plaque-forming viruses that infect certain chlorella-like green algae; the algae are normally mutualistic endosymbionts of protists and metazoans and are often referred to as zoochlorellae. The viruses are ubiquitous in inland aqueous environments throughout the world and occasionally single types reach titers of thousands of plaque-forming units per ml of native water. The viruses are icosahedral in shape with a spike structure located at one of the vertices. They contain an internal membrane that is required for infectivity. The viral genomes are 290 to 370 kb in size, which encode up to 16 tRNAs and 330 to ~415 proteins, including many not previously seen in viruses. Examples include genes encoding DNA restriction and modification enzymes, hyaluronan and chitin biosynthetic enzymes, polyamine biosynthetic enzymes, ion channel and transport proteins, and enzymes involved in the glycan synthesis of the virus major capsid glycoproteins. The proteins encoded by many of these viruses are often the smallest or among the smallest proteins of their class. Consequently, some of the viral proteins are the subject of intensive biochemical and structural investigation.

Durable Long-Term Bacterial Engraftment following Encapsulated Fecal Microbiota Transplantation To Treat Clostridium difficile Infection

Fecal microbiota transplantation (FMT) has become a common rescue therapy for recurrent Clostridium difficile infection, and encapsulated delivery (cFMT) of healthy donor microbiota shows similar clinical efficacy as more traditional routes of administration. In this study, we characterized long-term patterns of bacterial engraftment in a cohort of 18 patients, who received capsules from one of three donors, up to 409 days post-FMT. Bacterial communities were characterized using Illumina sequencing of the V5-V6 hypervariable regions of the 16S rRNA gene, and engraftment was determined by using the Bayesian algorithm SourceTracker. All patients recovered clinically and were free of C. difficile infection following cFMT. The majority of patients (61%) showed high levels of engraftment after the first week following FMT, which were sustained throughout the year. A small subset, 22%, experienced a decline in donor engraftment after approximately 1 month, and a few patients (17%), two of whom were taking metformin, showed delayed and low levels of donor engraftment. Members of the genera Bacteroides, Parabacteroides, and Faecalibacterium were significantly and positively correlated with donor similarity (ρ = 0.237 to 0.373, P ≤ 0.017). Furthermore, throughout the year, patient fecal communities showed significant separation based on the donor fecal microbiota that they received (P < 0.001). Results of this study, which characterize long-term engraftment following cFMT, suggest that numerical donor similarity is not strictly related to clinical outcome and identify a persistent donor-specific effect on patient fecal microbial communities. Furthermore, results suggest that members of the Bacteroidetes may be important targets to improve engraftment via cFMT.IMPORTANCE Recurrent Clostridium difficile infection (rCDI) is the most common cause of hospital- and community-acquired diarrheal infection associated with antibiotic use. Fecal microbiota transplantation (FMT), a treatment that involves administration of fecal bacteria from a healthy donor to a recipient patient, is a highly effective rescue therapy for rCDI that is increasingly being incorporated into standard clinical practice. Encapsulated, freeze-dried preparations of fecal microbiota, administered orally, offer the simplest and most convenient route of FMT delivery for patients (cFMT). In this study, we evaluated the extent of bacterial engraftment following cFMT and the duration of donor bacterial persistence. All patients studied recovered clinically but showed differing patterns in long-term microbial community similarity to the donor that were associated with members of the bacterial group Bacteroidetes, previously shown to be prominent contributors to rCDI resistance. Results highlight long-lasting, donor-specific effects on recipient patient microbiota and reveal potential bacterial targets to improve cFMT engraftment.

Clinical Review on the Utility of Fecal Microbiota Transplantation in Immunocompromised Patients

Fecal microbiota transplantation (FMT) represents a promising management modality for Clostridium difficile infection (CDI). In immunocompromised patients, FMT is utilized for CDI as well as emerging non-CDI indications such as inflammatory bowel disease and graft versus host disease. PURPOSE OF REVIEW: This review aims to shed light on the safety and efficacy of FMT in immunocompromised patients, including patients suffering for human immunodeficiency virus infection, solid organ and hematopoietic stem cell transplant recipients, cancer patients, and patients on immunosuppressive therapies. RECENT FINDINGS: Though the body of evidence concerning the use of FMT in immunocompromised is growing, no clinical trials exist to date. Present literature weighs in favor of FMT in immunocompromised patients, with an acceptable adverse effect profile and minimal risk of infectious adverse events. Further large scale studies and randomized controlled trials to validate the utility of FMT in immunocompromised individuals will be a welcomed endeavor.

The Super-Donor Phenomenon in Fecal Microbiota Transplantation

Fecal microbiota transplantation (FMT) has become a highly effective bacteriotherapy for recurrent Clostridium difficile infection. Meanwhile the efficacy of FMT for treating chronic diseases associated with microbial dysbiosis has so far been modest with a much higher variability in patient response. Notably, a number of studies suggest that FMT success is dependent on the microbial diversity and composition of the stool donor, leading to the proposition of the existence of FMT super-donors. The identification and subsequent characterization of super-donor gut microbiomes will inevitably advance our understanding of the microbial component of chronic diseases and allow for more targeted bacteriotherapy approaches in the future. Here, we review the evidence for super-donors in FMT and explore the concept of keystone species as predictors of FMT success. Possible effects of host-genetics and diet on FMT engraftment and maintenance are also considered. Finally, we discuss the potential long-term applicability of FMT for chronic disease and highlight how super-donors could provide the basis for dysbiosis-matched FMTs.

A Wake-Up Call: We Need Phage Therapy Now

The rise of multidrug-resistant bacteria has resulted in an increased interest in phage therapy, which historically preceded antibiotic treatment against bacterial infections. To date, there have been no reports of serious adverse events caused by phages. They have been successfully used to cure human diseases in Eastern Europe for many decades. More recently, clinical trials and case reports for a variety of indications have shown promising results. However, major hurdles to the introduction of phage therapy in the Western world are the regulatory and legal frameworks. Present regulations may take a decade or longer to be fulfilled. It is of urgent need to speed up the availability of phage therapy.

Gut fungal dysbiosis correlates with reduced efficacy of fecal microbiota transplantation in Clostridium difficile infection

Fecal microbiota transplantation (FMT) is effective in treating recurrent Clostridium difficile infection (CDI). Bacterial colonization in recipients after FMT has been studied, but little is known about the role of the gut fungal community, or mycobiota. Here, we show evidence of gut fungal dysbiosis in CDI, and that donor-derived fungal colonization in recipients is associated with FMT response. CDI is accompanied by over-representation of Candida albicans and decreased fungal diversity, richness, and evenness. Cure after FMT is associated with increased colonization of donor-derived fungal taxa in recipients. Recipients of successful FMT (“responders”) display, after FMT, a high relative abundance of Saccharomyces and Aspergillus, whereas “nonresponders” and individuals treated with antibiotics display a dominant presence of Candida. High abundance of C. albicans in donor stool also correlates with reduced FMT efficacy. Furthermore, C. albicans reduces FMT efficacy in a mouse model of CDI, while antifungal treatment reestablishes its efficacy, supporting a potential causal relationship between gut fungal dysbiosis and FMT outcome.

Fecal microbiota transplantation (FMT) is effective in treating recurrent Clostridium difficile infection (CDI). Here, the authors show that the composition of the gut fungal microbiota of donors and recipients, and especially the abundance of Candida, correlates with FMT outcome in CDI patients.

Bacteriophage transfer during faecal microbiota transplantation in Clostridium difficile infection is associated with treatment outcome

OBJECTIVE

Faecal microbiota transplantation (FMT) is effective for the treatment of recurrent Clostridium difficile infection (CDI). Studies have shown bacterial colonisation after FMT, but data on viral alterations in CDI are scarce. We investigated enteric virome alterations in CDI and the association between viral transfer and clinical outcome in patients with CDI.

DESIGN

Ultra-deep metagenomic sequencing of virus-like particle preparations and bacterial 16S rRNA sequencing were performed on stool samples from 24 subjects with CDI and 20 healthy controls. We longitudinally assessed the virome and bacterial microbiome changes in nine CDI subjects treated with FMT and five treated with vancomycin. Enteric virome alterations were assessed in association with treatment response.

RESULTS

Subjects with CDI demonstrated a significantly higher abundance of bacteriophage Caudovirales and a lower Caudovirales diversity, richness and evenness compared with healthy household controls. Significant correlations were observed between bacterial families Proteobacteria, Actinobacteria and Caudovirales taxa in CDI. FMT treatment resulted in a significant decrease in the abundance of Caudovirales in CDI. Cure after FMT was observed when donor-derived Caudovirales contigs occupied a larger fraction of the enteric virome in the recipients (p=0.024). In treatment responders, FMT was associated with alterations in the virome and the bacterial microbiome, while vancomycin treatment led to alterations in the bacterial community alone.

CONCLUSIONS

In a preliminary study, CDI is characterised by enteric virome dysbiosis. Treatment response in FMT was associated with a high colonisation level of donor-derived Caudovirales taxa in the recipient. Caudovirales bacteriophages may play a role in the efficacy of FMT in CDI.

TRIAL REGISTRATION NUMBER

NCT02570477.

The role of gut microbiota in Clostridium difficile infection

Clostridium difficile infection has emerged as a major health problem. Because it is a spore-forming microorganism, C. difficile is difficult to eradicate and recurrences of the infection are frequent. The strong association of CDI with prior use of antibiotics led to the recognition that disturbances in the gut microbiota apparently plays a central role in CDI. Except for antibiotics, several other risk factors for CDI have been recognised, such as advanced age and use of proton pump inhibitors. The common characteristic of these factors is that they are associated with changes in the composition of gut microbiota. Data from human studies have shown that the presence of C. difficile, either as a colonizer or as a pathogen, is associated with reduced microbiota diversity. C. difficile infection per se seems to be associated with changes in the representation of specific microbial populations (e.g. taxa) which either may act protectively against C. difficile colonization of the gut or may increase susceptibility for C. difficile infection. Therapeutic gut microbiota manipulation can be achieved by faecal microbiota transplantation, which is highly effective for the treatment of CDI.

Contemporary Applications of Fecal Microbiota Transplantation to Treat Intestinal Diseases in Humans

The intestinal microbiota comprise an important organ that plays a vital role in host digestion, development, energy maintenance, hemostasis, and immunity. Disruption of the gut microbial community due to diet, lifestyle, or antibiotic exposure increases susceptibility to chronic infection and disease. Fecal microbiota transplantation (FMT) involves the transfer of gut microbiota from a healthy donor to a patient in order to restore normal diversity and function of the microbial community. This method has become a well established alternative therapy for the treatment of recurrent Clostridium difficile infection. Recent clinical trials and studies in animal models suggest promise for this method to treat inflammatory bowel diseases, as well as metabolic syndrome. In addition, due to signaling interactions between the gut microbiota and brain, FMT has been suggested as a potential treatment for some psychological disorders, including autism spectrum disorder. Importantly, advances in next-generation sequencing and multi-omics approaches are increasingly improving our understanding of the mechanisms by which FMT results in cure of these various conditions. In this review, we summarize the current applications of FMT and highlight potential future uses and current challenges in understanding and optimizing FMT procedures.

RNase H As Gene Modifier, Driver of Evolution and Antiviral Defense

Retroviral infections are 'mini-symbiotic' events supplying recipient cells with sequences for viral replication, including the reverse transcriptase (RT) and ribonuclease H (RNase H). These proteins and other viral or cellular sequences can provide novel cellular functions including immune defense mechanisms. Their high error rate renders RT-RNases H drivers of evolutionary innovation. Integrated retroviruses and the related transposable elements (TEs) have existed for at least 150 million years, constitute up to 80% of eukaryotic genomes and are also present in prokaryotes. Endogenous retroviruses regulate host genes, have provided novel genes including the syncytins that mediate maternal-fetal immune tolerance and can be experimentally rendered infectious again. The RT and the RNase H are among the most ancient and abundant protein folds. RNases H may have evolved from ribozymes, related to viroids, early in the RNA world, forming ribosomes, RNA replicases and polymerases. Basic RNA-binding peptides enhance ribozyme catalysis. RT and ribozymes or RNases H are present today in bacterial group II introns, the precedents of TEs. Thousands of unique RTs and RNases H are present in eukaryotes, bacteria, and viruses. These enzymes mediate viral and cellular replication and antiviral defense in eukaryotes and prokaryotes, splicing, R-loop resolvation, DNA repair. RNase H-like activities are also required for the activity of small regulatory RNAs. The retroviral replication components share striking similarities with the RNA-induced silencing complex (RISC), the prokaryotic CRISPR-Cas machinery, eukaryotic V(D)J recombination and interferon systems. Viruses supply antiviral defense tools to cellular organisms. TEs are the evolutionary origin of siRNA and miRNA genes that, through RISC, counteract detrimental activities of TEs and chromosomal instability. Moreover, piRNAs, implicated in transgenerational inheritance, suppress TEs in germ cells. Thus, virtually all known immune defense mechanisms against viruses, phages, TEs, and extracellular pathogens require RNase H-like enzymes. Analogous to the prokaryotic CRISPR-Cas anti-phage defense possibly originating from TEs termed casposons, endogenized retroviruses ERVs and amplified TEs can be regarded as related forms of inheritable immunity in eukaryotes. This survey suggests that RNase H-like activities of retroviruses, TEs, and phages, have built up innate and adaptive immune systems throughout all domains of life.

Long-term taxonomic and functional divergence from donor bacterial strains following fecal microbiota transplantation in immunocompromised patients

Immunocompromised individuals are at high risk of developing Clostridium difficile-associated disease (CDAD). Fecal microbiota transplantation (FMT) is a highly effective therapy for refractory or recurrent CDAD and, despite safety concerns, has recently been offered to immunocompromised patients. We investigated the genomics of bacterial composition following FMT in immunocompromised patients over a 1-year period. Metagenomic, strain and gene-level bacterial dynamics were characterized in two CDAD-affected hematopoietic stem cell (HCT) recipients following FMT. We found alterations in gene content, including loss of virulence and antibiotic resistance genes. These alterations were accompanied by long-term bacterial divergence at the species and strain levels. Our findings suggest limited durability of the specific bacterial consortium introduced with FMT and indicate that alterations of the functional potential of the microbiome are more complex than can be inferred by taxonomic information alone. Our observation that FMT alone cannot induce long-term donor-like alterations of the microbiota of HCT recipients suggests that FMT cannot indefinitely supersede environmental and/or host factors in shaping bacterial composition.

The Human Gut Phage Community and Its Implications for Health and Disease

In this review, we assess our current understanding of the role of bacteriophages infecting the human gut bacterial community in health and disease. In general, bacteriophages contribute to the structure of their microbial communities by driving host and viral diversification, bacterial evolution, and by expanding the functional diversity of ecosystems. Gut bacteriophages are an ensemble of unique and shared phages in individuals, which encompass temperate phages found predominately as prophage in gut bacteria (prophage reservoir) and lytic phages. In healthy individuals, only a small fraction of the prophage reservoir is activated and found as extracellular phages. Phage community dysbiosis is characterized by a shift in the activated prophage community or an increase of lytic phages, and has been correlated with disease, suggesting that a proper balance between lysis and lysogeny is needed to maintain health. Consequently, the concept of microbial dysbiosis might be extended to the phage component of the microbiome as well. Understanding the dynamics and mechanisms to restore balance after dysbiosis is an active area of research. The use of phage transplants to re-establish health suggests that phages can be used as disease treatment. Such advances represent milestones in our understanding of gut phages in human health and should fuel research on their role in health and disease.

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.

Analysis of gut microbiota - An ever changing landscape

In the last two decades, the field of metagenomics has greatly expanded due to improvement in sequencing technologies allowing for a more comprehensive characterization of microbial communities. The use of these technologies has led to an unprecedented understanding of human, animal, and environmental microbiomes and have shown that the gut microbiota are comparable to an organ that is intrinsically linked with a variety of diseases. Characterization of microbial communities using next-generation sequencing-by-synthesis approaches have revealed important shifts in microbiota associated with debilitating diseases such as Clostridium difficile infection. But due to limitations in sequence read length, primer biases, and the quality of databases, genus- and species-level classification have been difficult. Third-generation technologies, such as Pacific Biosciences' single molecule, real-time (SMRT) approach, allow for unbiased, more specific identification of species that are likely clinically relevant. Comparison of Illumina next-generation characterization and SMRT sequencing of samples from patients treated for C. difficile infection revealed similarities in community composition at the phylum and family levels, but SMRT sequencing further allowed for species-level characterization - permitting a better understanding of the microbial ecology of this disease. Thus, as sequencing technologies continue to advance, new species-level insights can be gained in the study of complex and clinically-relevant microbial communities.

Understanding the mechanisms of faecal microbiota transplantation

This Review summarizes mechanistic investigations in faecal microbiota transplantation (FMT), which has increasingly been adapted into clinical practice as treatment for Clostridium difficile infection (CDI) that cannot be eliminated with antibiotics alone. Administration of healthy donor faecal microbiota in this clinical situation results in its engraftment and restoration of normal gut microbial community structure and functionality. In this Review, we consider several main mechanisms for FMT effectiveness in treatment of CDI, including direct competition of C. difficile with commensal microbiota delivered by FMT, restoration of secondary bile acid metabolism in the colon and repair of the gut barrier by stimulation of the mucosal immune system. Some of these mechanistic insights suggest possibilities for developing novel, next-generation CDI therapeutics. FMT might also have potential applications for non-CDI indications. The gut can become a reservoir of other potential antibiotic-resistant pathogens under pressure of antibiotic treatments, and restoration of normal microbial community structure by FMT might be a promising approach to protect against infections with these pathogens as well. Finally, FMT could be considered for multiple chronic diseases that are associated with some form of dysbiosis. However, considerable research is needed to optimize the FMT protocols for such applications before their therapeutic promise can be evaluated.

Long-term microbiota and virome in a Zürich patient after fecal transplantation against Clostridium difficile infection

Fecal microbiota transplantation (FMT) is an emerging therapeutic option for Clostridium difficile infections that are refractory to conventional treatment. FMT introduces fecal microbes into the patient's intestine that prevent the recurrence of C. difficile, leading to rapid expansion of bacteria characteristic of healthy microbiota. However, the long-term effects of FMT remain largely unknown. The C. difficile patient described in this paper revealed protracted microbiota adaptation processes from 6 to 42 months post-FMT. Ultimately, bacterial communities were donor similar, suggesting sustainable stool engraftment. Since little is known about the consequences of transmitted viruses during C. difficile infection, we also interrogated virome changes. Our approach allowed identification of about 10 phage types per sample that represented larger viral communities, and phages were found to be equally abundant in the cured patient and donor. The healthy microbiota appears to be characterized by low phage abundance. Although viruses were likely transferred, the patient established a virome distinct from the donor. Surprisingly, the patient had sequences of algal giant viruses (chloroviruses) that have not previously been reported for the human gut. Chloroviruses have not been associated with intestinal disease, but their presence in the oropharynx may influence cognitive abilities. The findings suggest that the virome is an important indicator of health or disease. A better understanding of the role of viruses in the gut ecosystem may uncover novel microbiota-modulating therapeutic strategies.