The Efficacy and Safety of Fecal Microbiota Transplant for Recurrent Clostridium difficile Infection: Current Understanding and Gap Analysis

Live Biotherapeutic Products for the Prevention of Recurrent Clostridioides difficile Infection

OBJECTIVE

To review the efficacy, safety, and role of live biotherapeutic products (LBPs) in the prevention of recurrent Clostridioides difficile infection (rCDI).

DATA SOURCES

A literature search was performed using PubMed and Google Scholar (through February 2024) with search terms RBX2660, SER-109, and fecal microbiota. Other resources included abstracts presented at recent conferences, national clinical practice guidelines, and manufacturers' websites.

STUDY SELECTION AND DATA EXTRACTION

All relevant studies, trial updates, conference abstracts, and guidelines in the English language were included.

DATA SYNTHESIS

Two LBPs were recently approved by the Food and Drug Administration for the prevention of recurrence in adults following antibiotic treatment for rCDI. Fecal microbiota, live-jslm is administered rectally as a retention enema, whereas fecal microbiota spores, live-brpk is given orally after bowel preparation. Several phase 2 and phase 3 clinical trials have established the safety and efficacy of these LBPs in reducing rates of rCDI compared with placebo. Patients with severe immunosuppression and those with inflammatory bowel disease were largely excluded from these trials.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE IN COMPARISON WITH EXISTING DRUGS

Live biotherapeutic products offer a similar mechanism to conventional fecal microbiota transplant (FMT) in preventing rCDI through microbiota restoration. The primary advantages of LBPs over FMT are their standardized composition and donor stool screening processes for transmissible pathogens. Bezlotoxumab is also available for the prevention of Clostridioides difficile infection; however, there are no clinical data available to compare the efficacy of LBPs with bezlotoxumab, and the benefit of simultaneous use of these preventative therapies is unclear.

CONCLUSIONS

Live biotherapeutic products provide a safe and effective option for the prevention of rCDI and represent an improvement over conventional FMT. Additional studies are needed to further determine their place in therapy relative to bezlotoxumab and in the setting of immunosuppression and inflammatory bowel disease.

Fecal microbiota transplantation in a patient with chronic diarrhea and primary and secondary immunodeficiency (common variable immunodeficiency and splenectomy)

The gut microbiota serves a crucial role in the development of host immunity. Immunocompromised patients are particularly vulnerable to dysbiosis not only by virtue of a defect in the immune system but also due to increased susceptibility to infection and multiple courses of antibiotic therapy. Fecal microbiota transplantation is by far the most effective option for restoring gastrointestinal homeostasis. However, it is contraindicated in patients with significant primary and secondary immunodeficiencies. This article presents the case of a 59-year-old patient with common variable immunodeficiency, after splenectomy at age 39 for primary immune thrombocytopenia, who manifested diarrhea of up to 10 stools per day accompanied by secondary malnutrition and cachexia. The patient was admitted to the hospital on multiple occasions due to this condition, with stool PCR tests confirming a HHV-5 (Cytomegalovirus, CMV) infection. Following the administration of valganciclovir, the patient's complaints diminished, although, upon cessation of the drug, the symptoms recurred. In addition, the patient had an intestinal infection with C. difficile etiology. Given that the patient's therapeutic options had been exhausted, after obtaining informed consent from the patient and approval from the bioethics committee to conduct a medical experiment, treatment of diarrhea was undertaken by fecal microbiota transplantation with the certified preparation Mbiotix HBI from the Human Biome Institute. The patient underwent two transplants, with a one-week interval between them. The initial procedure was performed using the endoscopic method, while the subsequent was conducted using the capsule method. Following the administration of the applied treatment, the patient's symptoms were successfully alleviated, and no adverse effects were observed. A microbiological analysis of the intestinal microbiota was conducted prior to and following transplantation via next-generation sequencing (NGS). No recurrence of symptoms was observed during the two-year follow-up period. To the best of our knowledge, this is the first fecal microbiota transplantation in an adult patient with primary and secondary immunodeficiency.

SinoNasal Microbiota Transfer to treat recalcitrant chronic rhinosinusitis: A case series

KEY POINTS

SinoNasal Microbiota Transfer (SNMT) was safe with immediate benefit in all recipients, with sustained improvement in two of three recipients for up to 180 days. The addition of antimicrobial photodynamic therapy worsened chronic rhinosinusitis. These promising SNMT results warrant further study of safety and efficacy.

Transfer of modified gut viromes improves symptoms associated with metabolic syndrome in obese male mice

Metabolic syndrome encompasses amongst other conditions like obesity and type-2 diabetes and is associated with gut microbiome (GM) dysbiosis. Fecal microbiota transplantation (FMT) has been explored to treat metabolic syndrome by restoring the GM; however, concerns on accidentally transferring pathogenic microbes remain. As a safer alternative, fecal virome transplantation (FVT, sterile-filtrated feces) has the advantage over FMT in that mainly bacteriophages are transferred. FVT from lean male donors have shown promise in alleviating the metabolic effects of high-fat diet in a preclinical mouse study. However, FVT still carries the risk of eukaryotic viral infections. To address this, recently developed methods are applied for removing or inactivating eukaryotic viruses in the viral component of FVT. Modified FVTs are compared with unmodified FVT and saline in a diet-induced obesity model on male C57BL/6 N mice. Contrasted with obese control, mice administered a modified FVT (nearly depleted for eukaryotic viruses) exhibits enhanced blood glucose clearance but not weight loss. The unmodified FVT improves liver pathology and reduces the proportions of immune cells in the adipose tissue with a non-uniform response. GM analysis suggests that bacteriophage-mediated GM modulation influences outcomes. Optimizing these approaches could lead to the development of safe bacteriophage-based therapies targeting metabolic syndrome through GM restoration.

Manufacturing Processes of a Purified Microbiome Therapeutic Reduce Risk of Transmission of Potential Bacterial Pathogens in Donor Stool

BACKGROUND

Although fecal microbiota transplant has been used to prevent recurrent Clostridioides difficile infection (rCDI), documented pathogen transmissions highlight inherent safety risks of minimally processed stool. We describe manufacturing processes for fecal microbiota spores, live (VOWST; VOS, formerly SER-109), a microbiota-based oral therapeutic of Firmicutes spores.

METHODS

Bacterial inactivation kill curves were obtained after ethanol exposure for 4 model organisms spiked into process intermediates.

RESULTS

Bacterial log reduction factors ranged from 6.5 log10 to 7.4 log10 and lysis of spiked organisms occurred rapidly within 30 seconds.

CONCLUSIONS

These experiments demonstrate substantial and rapid inactivation of representative organisms, supporting the potential benefit of VOS manufacturing processes to mitigate risk.

Unveiling the hidden world of gut health: Exploring cutting-edge research through visualizing randomized controlled trials on the gut microbiota

BACKGROUND

The gut microbiota plays a crucial role in gastrointestinal and overall health. Randomized clinical trials (RCTs) play a crucial role in advancing our knowledge and evaluating the efficacy of therapeutic interventions targeting the gut microbiota.

AIM

To conduct a comprehensive bibliometric analysis of the literature on RCTs involving the gut microbiota.

METHODS

Using bibliometric tools, a descriptive cross-sectional investigation was conducted on scholarly publications concentrated on RCTs related to gut microbiota, spanning the years 2003 to 2022. The study used VOSviewer version 1.6.9 to examine collaboration networks between different countries and evaluate the frequently employed terms in the titles and abstracts of the retrieved publications. The primary objective of this analysis was to identify key research areas and focal points associated with RCTs involving the gut microbiota.

RESULTS

A total of 1061 relevant articles were identified from the 24758 research articles published between 2003 and 2022. The number of publications showed a notable increase over time, with a positive correlation (R2 = 0.978, P < 0.001). China (n = 276, 26.01%), the United States (n = 254, 23.94%), and the United Kingdom (n = 97, 9.14%) were the leading contributing countries. Københavns Universitet (n = 38, 3.58%) and Dankook University (n = 35, 3.30%) were the top active institutions. The co-occurrence analysis shows current gut microbiota research trends and important topics, such as obesity interventions targeting the gut microbiota, the efficacy and safety of fecal microbiota transplantation, and the effects of dietary interventions on humans.

CONCLUSION

The study highlights the rapid growth and importance of research on RCTs that involve the gut microbiota. This study provides valuable insight into research trends, identifies key players, and outlines potential future directions in this field. Additionally, the co-occurrence analysis identified important topics that play a critical role in the advancement of science and provided insights into future research directions in this field.

Update on Clostridioides difficile Infection in Older Adults

Clostridioides difficile is a common cause of community-associated and health care-associated infections. Older adults are disproportionately affected, and long-term care facilities (LTCFs) have borne a substantial proportion of the burden of C difficile infection (CDI). Recurrences of CDI are common in older adults and have substantial adverse effects on quality of life. Appropriate diagnostic testing and management is essential for older adults in the community and in LTCFs. This review focuses on current concepts related to the epidemiology, diagnosis, and management of CDI in older adults.

Microbiome therapeutics for the treatment of recurrent Clostridioides difficile infection

INTRODUCTION

The gut microbiome is implicated in Clostridioides difficile infection (CDI) and recurrent CDI (rCDI).

AREAS COVERED

This review covers the mechanisms by which microbiome therapeutics treat rCDI, their efficacy and safety, and clinical trial design considerations for future research.

EXPERT OPINION

Altering the chemical environment of the gut and reconstituting colonization resistance is a promising strategy for preventing and treating rCDI. Fecal microbiota transplant (FMT) is safe and effective for the treatment of rCDI. However, limitations of FMT have prompted investigation into alternative microbiome therapeutics. These alternative microbiome therapies require further evaluation, and adaptive trial designs should be strongly considered to more rapidly discern variables including the need for bowel preparation, timing and selection of pre-treatment antibiotics, and dose and duration of microbiome therapeutics. A broad range of adverse events must be prospectively evaluated in these controlled trials, as microbiome therapeutics have the potential for numerous effects. Future studies will lead to a greater understanding of the mechanisms by which microbiome therapies can break the cycle of rCDI, which should ultimately yield a personalized approach to rCDI treatment that restores an individual's specific deficit(s) in colonization resistance to C. difficile.

Drugging the microbiome and bacterial live biotherapeutic consortium production

Research leading to characterization, quantification, and functional attribution of the microbes throughout the human body has led to many drug-development programs. These programs aim to manipulate a patient's microbiome through the addition of new strains or functions, the subtraction of deleterious microbes, or the rebalancing of the existing population through various drug modalities. Here, we present a general overview of those modalities with a specific focus on bacterial live biotherapeutic products (LBPs). The bacterial LBP modality has unique concerns to ensure product quality, thus, topics related to manufacturing, quality control, and regulation are addressed.

SER-109: An Oral Investigational Microbiome Therapeutic for Patients with Recurrent Clostridioides difficile Infection (rCDI)

Clostridioides difficile infection (CDI) is classified as an urgent health threat by the Centers for Disease Control and Prevention (CDC), and affects nearly 500,000 Americans annually. Approximately 20−25% of patients with a primary infection experience a recurrence, and the risk of recurrence increases with subsequent episodes to greater than 40%. The leading risk factor for CDI is broad-spectrum antibiotics, which leads to a loss of microbial diversity and impaired colonization resistance. Current FDA-approved CDI treatment strategies target toxin or toxin-producing bacteria, but do not address microbiome disruption, which is key to the pathogenesis of recurrent CDI. Fecal microbiota transplantation (FMT) reduces the risk of recurrent CDI through the restoration of microbial diversity. However, FDA safety alerts describing hospitalizations and deaths related to pathogen transmission have raised safety concerns with the use of unregulated and unstandardized donor-derived products. SER-109 is an investigational oral microbiome therapeutic composed of purified spore-forming Firmicutes. SER-109 was superior to a placebo in reducing CDI recurrence at Week 8 (12% vs. 40%, respectively; p < 0.001) in adults with a history of recurrent CDI with a favorable observed safety profile. Here, we discuss the role of the microbiome in CDI pathogenesis and the clinical development of SER-109, including its rigorous manufacturing process, which mitigates the risk of pathogen transmission. Additionally, we discuss compositional and functional changes in the gastrointestinal microbiome in patients with recurrent CDI following treatment with SER-109 that are critical to a sustained clinical response.

Type 2 diabetes, gut microbiome, and systems biology: A novel perspective for a new era

The association between the physio-pathological variables of type 2 diabetes (T2D) and gut microbiota composition suggests a new avenue to track the disease and improve the outcomes of pharmacological and non-pharmacological treatments. This enterprise requires new strategies to elucidate the metabolic disturbances occurring in the gut microbiome as the disease progresses. To this end, physiological knowledge and systems biology pave the way for characterizing microbiota and identifying strategies in a move toward healthy compositions. Here, we dissect the recent associations between gut microbiota and T2D. In addition, we discuss recent advances in how drugs, diet, and exercise modulate the microbiome to favor healthy stages. Finally, we present computational approaches for disentangling the metabolic activity underlying host-microbiota codependence. Altogether, we envision that the combination of physiology and computational modeling of microbiota metabolism will drive us to optimize the diagnosis and treatment of T2D patients in a personalized way.

Bioengineered 3D Tissue Model of Intestine Epithelium with Oxygen Gradients to Sustain Human Gut Microbiome

The human gut microbiome is crucial to hosting physiology and health. Therefore, stable in vitro coculture of primary human intestinal cells with a microbiome community is essential for understanding intestinal disease progression and revealing novel therapeutic targets. Here, a three-dimensional scaffold system is presented to regenerate an in vitro human intestinal epithelium that recapitulates many functional characteristics of the native small intestines. The epithelium, derived from human intestinal enteroids, contains mature intestinal epithelial cells and possesses selectively permeable barrier functions. Importantly, by properly positioning the scaffolds cultured under normal atmospheric conditions, two physiologically relevant oxygen gradients, a proximal-to-distal oxygen gradient along the gastrointestinal (GI) tract, and a radial oxygen gradient across the epithelium, are distinguished in the tissues when the lumens are faced up and down in cultures, respectively. Furthermore, the presence of the low oxygen gradients supported the coculture of intestinal epithelium along with a complex living commensal gut microbiome (including obligate anaerobes) to simulate temporal microbiome dynamics in the native human gut. This unique silk scaffold platform may enable the exploration of microbiota-related mechanisms of disease pathogenesis and host-pathogen dynamics in infectious diseases including the potential to explore the human microbiome-gut-brain axis and potential novel microbiome-based therapeutics.

Clostridioides difficile toxins: mechanisms of action and antitoxin therapeutics

Clostridioides difficile is a Gram-positive anaerobe that can cause a spectrum of disorders that range in severity from mild diarrhoea to fulminant colitis and/or death. The bacterium produces up to three toxins, which are considered the major virulence factors in C. difficile infection. These toxins promote inflammation, tissue damage and diarrhoea. In this Review, we highlight recent biochemical and structural advances in our understanding of the mechanisms that govern host-toxin interactions. Understanding how C. difficile toxins affect the host forms a foundation for developing novel strategies for treatment and prevention of C. difficile infection.

Next-generation sequencing: insights to advance clinical investigations of the microbiome

Next-generation sequencing (NGS) technology has advanced our understanding of the human microbiome by allowing for the discovery and characterization of unculturable microbes with prediction of their function. Key NGS methods include 16S rRNA gene sequencing, shotgun metagenomic sequencing, and RNA sequencing. The choice of which NGS methodology to pursue for a given purpose is often unclear for clinicians and researchers. In this Review, we describe the fundamentals of NGS, with a focus on 16S rRNA and shotgun metagenomic sequencing. We also discuss pros and cons of each methodology as well as important concepts in data variability, study design, and clinical metadata collection. We further present examples of how NGS studies of the human microbiome have advanced our understanding of human disease pathophysiology across diverse clinical contexts, including the development of diagnostics and therapeutics. Finally, we share insights as to how NGS might further be integrated into and advance microbiome research and clinical care in the coming years.

Durable reduction of Clostridioides difficile infection recurrence and microbiome restoration after treatment with RBX2660: results from an open-label phase 2 clinical trial

Background

Effective treatment options for recurrent Clostridioides difficile infection (rCDI) are limited, with high recurrence rates associated with the current standard of care. Herein we report results from an open-label Phase 2 trial to evaluate the safety, efficacy, and durability of RBX2660—a standardized microbiota-based investigational live biotherapeutic—and a closely-matched historical control cohort.

Methods

This prospective, multicenter, open-label Phase 2 study enrolled patients who had experienced either ≥ 2 recurrences of CDI, treated by standard-of-care antibiotic therapy, after a primary CDI episode, or ≥ 2 episodes of severe CDI requiring hospitalization. Participants received up to 2 doses of RBX2660 rectally administered with doses 7 days apart. Treatment success was defined as the absence of CDI diarrhea without the need for retreatment for 8 weeks after completing study treatment. A historical control group with matched inclusion and exclusion criteria was identified from a retrospective chart review of participants treated with standard-of-care antibiotics for recurrent CDI who matched key criteria for the study. The primary objective was to compare treatment success of RBX2660 to the historical control group. A key secondary outcome was the safety profile of RBX2660, including adverse events and CDI occurrence through 24 months after treatment. In addition, fecal samples from RBX2660-treated participants were sequenced to evaluate microbiome composition and functional changes from before to after treatment.

Results

In this Phase 2 open-label clinical trial, RBX2660 demonstrated a 78.9% (112/142) treatment success rate compared to a 30.7% (23/75) for the historical control group (p < 0.0001; Chi-square test). Post-hoc analysis indicated that 91% (88/97) of evaluable RBX2660 responders remained CDI occurrence-free to 24 months after treatment demonstrating durability. RBX2660 was well-tolerated with mostly mild to moderate adverse events. The composition and diversity of RBX2660 responders’ fecal microbiome significantly changed from before to after treatment to become more similar to RBX2660, and these changes were durable to 24 months after treatment.

Conclusions

In this Phase 2 trial, RBX2660 was safe and effective for reducing rCDI recurrence as compared to a historical control group. Microbiome changes are consistent with restorative changes implicated in resisting C. difficile recurrence.

Clinical Trials Registration NCT02589847 (10/28/2015)

Validation of Two Commercial Multiplex Real-Time PCR Assays for Detection of SARS-CoV-2 in Stool Donors for Fecal Microbiota Transplantation

Recurrent infection by Clostridioides difficile has recently been treated by fecal microbiota transplantation (FMT). As viable SARS-CoV-2 was recovered from stool of asymptomatic individuals, the FMT procedure could be a potential risk of SARS-CoV-2 transmission, thus underlying the need to reliably detect SARS-CoV-2 in stool. Here, we performed a multicentric study to explore performances of two commercially available assays for detection of SARS-CoV-2 RNA in stool of potential FMT donors. In three hospitals, 180 stool samples were spiked with serial 10-fold dilutions of a SARS-CoV-2 inactivated lysate to evaluate the Seegene Allplex™ SARS-CoV-2 (SC2) and SARS-CoV-2/FluA/FluB/RSV (SC2FABR) Assays for the detection of viral RNA in stool of FMT donors. The results revealed that both assays detected down to 2 TCID50/mL with comparable limit of detection values, SC2 showing more consistent target positivity rate than SC2FABR. Beyond high amplification efficiency, correlation between CT values and log concentrations of inactivated viral lysates showed R2 values ranging from 0.88 to 0.90 and from 0.87 to 0.91 for the SC2 and SC2FABR assay, respectively. The present results demonstrate that both methods are highly reproducible, sensitive, and accurate for SARS-CoV-2 RNA detection in stool, suggesting a potential use in FMT-donor screening.

The potential of microbiome replacement therapies for Clostridium difficile infection

PURPOSE OF REVIEW

There is a paradox when treating Clostridium difficile infection (CDI); treatment antibiotics reduce C. difficile colonization but cause further microbiota disruption and can lead to recurrent disease. The success of faecal microbiota transplants (FMT) in treating CDI has become a new research area in microbiome restorative therapies but are they a viable long-term treatment option?

RECENT FINDINGS

C. difficile displays metabolic flexibility to use different nutritional sources during CDI. Using microbiome therapies for the efficient restoration of bile homeostasis and to reduce the bioavailability of preferential nutrients will target the germination ability of C. difficile spores and the growth rate of vegetative cells. Several biotechnology companies have developed microbiome therapeutics for treating CDI, which are undergoing clinical trials.

SUMMARY

There is confidence in using restorative microbiome therapies for treating CDI after the demonstrated efficacy of FMT, where several biotechnology companies are aiming to supply what would be a 'first in class' treatment option. Efficient removal of C. difficile from the different intestinal biogeographies should be considered in future microbiome therapies. With the gut microbiota implicated in different diseases, more work is needed to assess the long-term consequences of microbiome therapies.

Menace of antimicrobial resistance in LMICs: Current surveillance practices and control measures to tackle hostility

Antimicrobial Resistance (AMR) is significant challenge humanity faces today, with many patients losing their lives every year due to AMR. It is more widespread and has shown a higher prevalence in low- and middle-income countries (LMICs) due to lack of awareness and other associated reasons. WHO has suggested some crucial guidelines and specific strategies such as antimicrobial stewardship programs taken at the institutional level to combat AMR. Creating awareness at the grassroots level can help to reduce the AMR and promote safe and effective use of antimicrobials. Control strategies in curbing AMR also comprise hygiene and sanitation as microbes travel from contaminated surroundings to the human body surface. As resistance to multiple drugs increases, vaccines can play a significant role in curbing the menace of AMR. This article summarizes the current surveillance practices and applied control measures to tackle the hostility in these countries with particular reference to the role of antimicrobial stewardship programs and the responsibilities of regulatory authorities in managing the situation.

Antibiotics at the crossroads - Do we have any therapeutic alternatives to control the emergence and spread of antimicrobial resistance?

Antibiotics once regarded as magic bullets are no more considered so. Overuse of antibiotics in humans, agriculture, and animal husbandry has resulted in the emergence of a wide range of multidrug-resistant (MDR) pathogens which are difficult to treat. Antimicrobial resistance (AMR) is a serious global health problem associated with high mortality in the era of modern medicine. Moreover, in the absence of an effective antibiotic, medical and surgical interventions can highly become a risk. In recent times, the decreased incline of pharmaceutical industries toward research and development of newer effective antibiotics to fight this MDR pathogens have further fuelled the scarcity of antibiotics, thus the number of antibiotics in the pipeline is extremely limited. Hence it is high time for the development of new strategies to fight against dangerous MDR pathogens. Currently, several novel approaches explored by scientists have shown promising results pertaining to their antimicrobial activity against pathogens. In this article, the authors have summarized various novel therapeutic options explored to contain AMR with special attention to the mechanism of action, advantages, and disadvantages of different approaches.

Regulation of para-cresol production in Clostridioides difficile

The human pathogen Clostridioides difficile colonises the gastrointestinal tract following antibiotic exposure, which causes perturbations in the beneficial microbiome. An unusual feature of C. difficile among the gut microbiota is its ability to produce high concentrations of the antimicrobial compound para-cresol, which selectively targets Gram-negative bacteria. Production of p-cresol occurs either by: (a) tyrosine fermentation via the intermediate para-hydroxyphenylacetate (p-HPA), or (b) direct turnover of exogenous p-HPA in the human gut. p-HPA is decarboxylated to produce p-cresol, by the action of HpdBCA decarboxylase encoded by the hpdBCA operon. HpdBCA decarboxylase production is induced at the transcriptional level by elevated p-HPA, which causes elevated p-cresol production, that significantly reduces microbiome diversity and richness. This deleterious effect of p-cresol on the beneficial gut microbiome is advantageous for C. difficile pathogenesis and infection relapse. Inhibiting this pathway would provide a highly specific therapeutic.

Frontiers in antibiotic alternatives for Clostridioides difficile infection

Clostridioides difficile (C. difficile) is a gram-positive, anaerobic spore-forming bacterium and a major cause of antibiotic-associated diarrhea. Humans are naturally resistant to C. difficile infection (CDI) owing to the protection provided by healthy gut microbiota. When the gut microbiota is disturbed, C. difficile can colonize, produce toxins, and manifest clinical symptoms, ranging from asymptomatic diarrhea and colitis to death. Despite the steady-if not rising-prevalence of CDI, it will certainly become more problematic in a world of antibiotic overuse and the post-antibiotic era. C. difficile is naturally resistant to most of the currently used antibiotics as it uses multiple resistance mechanisms. Therefore, current CDI treatment regimens are extremely limited to only a few antibiotics, which include vancomycin, fidaxomicin, and metronidazole. Therefore, one of the main challenges experienced by the scientific community is the development of alternative approaches to control and treat CDI. In this Frontier article, we collectively summarize recent advances in alternative treatment approaches for CDI. Over the past few years, several studies have reported on natural product-derived compounds, drug repurposing, high-throughput library screening, phage therapy, and fecal microbiota transplantation. We also include an update on vaccine development, pre- and pro-biotics for CDI, and toxin antidote approaches. These measures tackle CDI at every stage of disease pathology via multiple mechanisms. We also discuss the gaps and concerns in these developments. The next epidemic of CDI is not a matter of if but a matter of when. Therefore, being well-equipped with a collection of alternative therapeutics is necessary and should be prioritized.

Host genetic control of gut microbiome composition

The gut microbiome plays a significant role in health and disease, and there is mounting evidence indicating that the microbial composition is regulated in part by host genetics. Heritability estimates for microbial abundance in mice and humans range from (0.05-0.45), indicating that 5-45% of inter-individual variation can be explained by genetics. Through twin studies, genetic association studies, systems genetics, and genome-wide association studies (GWAS), hundreds of specific host genetic loci have been shown to associate with the abundance of discrete gut microbes. Using genetically engineered knock-out mice, at least 30 specific genes have now been validated as having specific effects on the microbiome. The relationships among of host genetics, microbiome composition, and abundance, and disease is now beginning to be unraveled through experiments designed to test causality. The genetic control of disease and its relationship to the microbiome can manifest in multiple ways. First, a genetic variant may directly cause the disease phenotype, resulting in an altered microbiome as a consequence of the disease phenotype. Second, a genetic variant may alter gene expression in the host, which in turn alters the microbiome, producing the disease phenotype. Finally, the genetic variant may alter the microbiome directly, which can result in the disease phenotype. In order to understand the processes that underlie the onset and progression of certain diseases, future research must take into account the relationship among host genetics, microbiome, and disease phenotype, and the resources needed to study these relationships.

Silent hypoxia in COVID-19: a gut microbiota connection

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has triggered the COVID-19 pandemic. Several factors induce hypoxia in COVID-19. Despite being hypoxic, some SARS-CoV-2-infected individuals do not experience any respiratory distress, a phenomenon termed ‘silent (or happy) hypoxia’. Prolonged undetected hypoxia could be dangerous, sometimes leading to death. A few studies attempted to unravel what causes silent hypoxia, however, the exact mechanisms are still elusive. Here, we aim to understand how SARS-CoV-2 causes silent hypoxia.

Safety of fecal microbiota transplantation for Clostridioides difficile infection focusing on pathobionts and SARS-CoV-2

Clostridioides difficile infection (CDI) is a consequence of flagrant use of antibiotics, an aging population with increasing comorbidities, and increased hospitalizations. The treatment of choice for CDI is antibiotics (vancomycin or fidaxomicin), with a possibility of recurrent CDI despite lack of additional risk factors for CDI. For the last 10 years, fecal microbiota transplantation (FMT) has emerged as a promising therapy for recurrent CDI, with success rates of over 85% compared with less than 50% with antibiotics for multiple recurrent CDI. Along with the success of FMT, several adverse and serious adverse events with FMT have been reported. These range from self-limiting abdominal pain to death due to severe sepsis. This review focuses on the safety of FMT, emphasizing the reports of transmission of pathobionts like extended-spectrum beta lactamase Escherichia coli and Shiga toxin-producing E. coli. The severe acute respiratory syndrome coronavirus-2 is a potential pathogen that could be transmitted via FMT during the COVID-19 pandemic. The challenges faced by clinicians for donor screening, clinical trials, and other aspects of FMT during the pandemic are discussed.

Fecal microbiota transplants: A review of emerging clinical data on applications, efficacy, and risks (2015-2020)

As the importance of the gut microbiota in health and disease is a subject of growing interest, fecal microbiota transplantation (FMT) was suggested as an attractive therapeutic strategy to restore homeostasis of the gut microbiota, thereby treating diseases that were associated with alteration of the gut microbiota. FMT involves the administration of fresh, frozen, or dried fecal microorganisms from the gut of a healthy donor into the intestinal tract of a patient. This rediscovery of the potential benefits of an ancient practice was accompanied by a rapid progression of our understanding of the roles and mechanisms of gut microbes in the pathogenesis of disease. With a growing number of diseases being associated with dysbiosis or the alteration of gut microbiota, FMT was suggested as an attractive therapeutic strategy to "reset the gut" and initiate clinical resolutions or remissions. The number of FMT clinical trials is increasing worldwide, but no trials are registered in the Gulf region; this suggested the need for raising awareness of the latest studies on FMT. This review presented the emergent preclinical and clinical data to give an overview of the potential clinical applications, the benefits, and inconveniences that were worth considering for eventual future testing of fecal transplants in Qatar and the Middle East. This study highlighted the diversity of methods tested and commented on the variables that can affect the assessment of the effectiveness of FMT in specific diseases. The risks associated with FMT and the threat of antimicrobial resistance for this therapeutic approach were reviewed. From gastrointestinal diseases to neurodevelopmental disorders, understanding the roles of the gut microbiota in health and disease should be at the heart of developing novel, standardized, yet personalized, methods for this ancient therapeutic approach.

Sub-Saharan African information potential to unveil adaptations to infectious disease

Sub-Saharan Africa is the most promising region of the world to conduct high-throughput studies to unveil adaptations to infectious diseases due to several reasons, namely, the longest evolving time-depth in the Homo sapiens phylogenetic tree (at least two-third older than any other worldwide region); the continuous burden of infectious diseases (still number one in health/life threat); and the coexistence of populations practising diverse subsistence modes (nomadic or seminomadic hunter-gatherers and agropastoralists, and sedentary agriculturalists, small urban and megacity groups). In this review, we will present the most up-to-date results that shed light on three main hypotheses related with this adaptation. One is the hypothesis of coevolution between host and pathogen, given enough time for the establishment of this highly dynamic relationship. The second hypothesis enunciates that the agricultural transition was responsible for the increase of the infectious disease burden, due to the huge expansion of the sedentary human population and the cohabitation with domesticates as main reservoirs of pathogens. The third hypothesis states that the boosting of our immune system against pathogens by past selection may have resulted in maladaptation of the developed hygienic societies, leading to an increase of allergic, inflammatory and autoimmune disorders. Further work will enlighten the biological mechanisms behind these main adaptations, which can be insightful for translation into diagnosis, prognosis and treatment interventions.

A Phase 1b Safety Study of SER-287, a Spore-Based Microbiome Therapeutic, for Active Mild to Moderate Ulcerative Colitis

BACKGROUND & AIMS

Firmicutes bacteria produce metabolites that maintain the intestinal barrier and mucosal immunity. Firmicutes are reduced in the intestinal microbiota of patients with ulcerative colitis (UC). In a phase 1b trial of patients with UC, we evaluated the safety and efficacy of SER-287, an oral formulation of Firmicutes spores, and the effects of vancomycin preconditioning on expansion (engraftment) of SER-287 species in the colon.

METHODS

We conducted a double-blind trial of SER-287 in 58 adults with active mild-to-moderate UC (modified Mayo scores 4-10, endoscopic subscores ≥1). Participants received 6 days of preconditioning with oral vancomycin (125 mg, 4 times daily) or placebo followed by 8 weeks of oral SER-287 or placebo. Patients were randomly assigned (2:3:3:3) to groups that received placebo followed by either placebo or SER-287 once weekly, or vancomycin followed by SER-287 once weekly, or SER-287 once daily. Clinical end points included safety and clinical remission (modified Mayo score ≤2; endoscopic subscores 0 or 1). Microbiome end points included SER-287 engraftment (dose species detected in stool after but not before SER-287 administration). Engraftment of SER-287 and changes in microbiome composition and associated metabolites were measured by analyses of stool specimens collected at baseline, after preconditioning, and during and 4 weeks after administration of SER-287 or placebo.

RESULTS

Proportions of patients with adverse events did not differ significantly among groups. A higher proportion of patients in the vancomycin/SER-287 daily group (40%) achieved clinical remission at week 8 than patients in the placebo/placebo group (0%), placebo/SER-287 weekly group (13.3%), or vancomycin/SER-287 weekly group (17.7%) (P = .024 for vancomycin/SER-287 daily vs placebo/placebo). By day 7, higher numbers of SER-287 dose species were detected in stool samples from all SER-287 groups compared with the placebo group (P < .05), but this difference was not maintained beyond day 7 in the placebo/SER-287 weekly group. In the vancomycin groups, a greater number of dose species were detected in stool collected on day 10 and all subsequent time points through 4 weeks post dosing compared with the placebo group (P < .05). A higher number of SER-287 dose species were detected in stool samples on days 7 and 10 from subjects who received daily vs weekly SER-287 doses (P < .05). Changes in fecal microbiome composition and metabolites were associated with both vancomycin/SER-287 groups.

CONCLUSIONS

In this small phase 1b trial of limited duration, the safety and tolerability of SER-287 were similar to placebo. SER-287 after vancomycin was significantly more effective than placebo for induction of remission in patients with active mild to moderate UC. Engraftment of dose species was facilitated by vancomycin preconditioning and daily dosing of SER-287. ClinicalTrials.gov ID NCT02618187.

Faecal microbiota transplantation for recurrent Clostridioides difficile infection: An updated systematic review and meta-analysis

BACKGROUND

Faecal microbiota transplantation (FMT) is effective for recurrent Clostridioides difficile infection (CDI), but inconsistent effect rates and uncertain evidence levels have warranted caution. To clarify, we aimed to establish the evidence of FMT for recurrent CDI, updated across different delivery methods, treatment regimens, and in comparison with standard antibiotics.

METHODS

In this updated systematic review and meta-analysis, we searched PubMed, Scopus, Embase, Web of Science, Clinical Key, and Svemed+ for FMT literature published in English until November 11, 2019. We included observational and clinical trials with or without antibiotic comparators and excluded studies with below 8 weeks follow-up and fewer than 15 patients. The primary outcome was clinical outcome by week 8. We comprehensively extracted patient and procedural data. In a random-effects meta-analysis, we estimated the clinical effect for repeat or single FMT, different delivery methods, and versus antibiotics. We rated the evidence according to the Cochrane and GRADE methods. The PROSPERO preregistration number is CRD42020158112.

FINDINGS

Of 1816 studies assessed, 45 studies were included. The overall clinical effect week 8 following repeat FMT (24 studies, 1855 patients) was 91% (95% CI: 89-94%, I 2=53%) and 84% (80-88%, I 2=86%) following single FMT (43 studies, 2937 patients). Delivery by lower gastrointestinal endoscopy was superior to all other delivery methods, and repeat FMT significantly increased the treatment effect week 8 (P<0·001). Compared with vancomycin, the number needed to treat (NNT) for repeat FMT was 1·5 (1·3-1·9, P<0·001) and 2.9 (1·5-37·1, P=0·03) for single FMT. Repeat FMT had high quality of evidence.

INTERPRETATION

High-quality evidence supports FMT is effective for recurrent CDI, but its effect varies with the delivery method and the number of administrations. The superior NNT for FMT compared with antibiotics suggests that patients may benefit from advancing FMT to all instances of recurrent CDI.

FUNDING

Innovation Fund Denmark (j.no. 8056-00006B).

Gastrointestinal symptoms associated with COVID-19: impact on the gut microbiome

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the greatest worldwide pandemic since the 1918 flu. The consequences of the coronavirus disease 2019 (COVID-19) are devastating and represent the current major public health issue across the globe. At the onset, SARS-CoV-2 primarily attacks the respiratory system as it represents the main point of entry in the host, but it also can affect multiple organs. Although most of the patients do not present symptoms or are mildly symptomatic, some people infected with SARS-CoV-2 that experience more severe multiorgan dysfunction. The severity of COVID-19 is typically combined with a set of comorbidities such as hypertension, diabetes, obesity, and/or advanced age that seriously exacerbates the consequences of the infection. Also, SARS-CoV-2 can cause gastrointestinal symptoms, such as vomiting, diarrhea, or abdominal pain during the early phases of the disease. Intestinal dysfunction induces changes in intestinal microbes, and an increase in inflammatory cytokines. Thus, diagnosing gastrointestinal symptoms that precede respiratory problems during COVID-19 may be necessary for improved early detection and treatment. Uncovering the composition of the microbiota and its metabolic products in the context of COVID-19 can help determine novel biomarkers of the disease and help identify new therapeutic targets. Elucidating changes to the microbiome as reliable biomarkers in the context of COVID-19 represent an overlooked piece of the disease puzzle and requires further investigation.