Vaccination to Reduce Antimicrobial Resistance Burden-Data Gaps and Future Research.

Antimicrobial resistance (AMR) poses an immediate danger to global health. If unaddressed, the current upsurge in AMR threatens to reverse the achievements in reducing the infectious disease-associated mortality and morbidity associated with antimicrobial treatment. Consequently, there is an urgent need for strategies to prevent or slow the progress of AMR. Vaccines potentially contribute both directly and indirectly to combating AMR. Modeling studies have indicated significant gains from vaccination in reducing AMR burdens for specific pathogens, reducing mortality/morbidity, and economic loss. However, quantifying the real impact of vaccines in these reductions is challenging because many of the study designs used to evaluate the contribution of vaccination programs are affected by significant background confounding, and potential selection and information bias. Here, we discuss challenges in assessing vaccine impact to reduce AMR burdens and suggest potential approaches for vaccine impact evaluation nested in vaccine trials.

Clinical Manifestations and Stool Load of Atypical Enteropathogenic Escherichia coli Infections in United States Children and Adults.

BACKGROUND & AIMS: There is debate whether atypical enteropathogenic Escherichia coli (aEPEC) causes disease in adults. aEPEC is commonly detected in symptomatic and asymptomatic individuals. aEPEC, in contrast to typical EPEC, lacks bundle-forming pili, altering its pathogenicity. Here, we define for the first time the clinical manifestations of sporadic aEPEC infection in United States children and adults and determine whether EPEC load correlates with disease. METHODS: This is a retrospective case-control study of 380 inpatients/outpatients of all ages. EPEC load in stools was determined by quantitative polymerase chain reaction. RESULTS: Diarrhea, vomiting, abdominal pain, and fever were more prevalent in EPEC-positive cases than in EPEC-negative controls. aEPEC infection caused mostly acute, mild diarrhea lasting for 6 to 13 days. However, some had severe diarrhea with 10 to 40 bowel movements per day or had persistent/chronic diarrhea. Fever, vomiting, and abnormal serum sodium levels were more common in children. Adults more often reported abdominal pain and longer duration of diarrhea. Symptomatic aEPEC infection was associated with leukocytosis in 24% of patients. EPEC load >0.1% was associated with symptomatic infection; however, loads varied greatly. Co-infecting pathogens did not alter diarrhea severity or EPEC load. Longitudinal data reveal that some are colonized for months to years or are repeatedly infected. CONCLUSIONS: aEPEC is associated with a wide array of symptoms in adults, ranging from asymptomatic carriage to severe diarrhea. Higher EPEC loads are associated with presence of symptoms, but bacterial load does not predict disease or severity. Future studies are needed to understand bacterial and host factors that contribute to aEPEC pathogenicity to improve diagnostic tools and clinical care.

Pilot study of autologous fecal microbiota transplants in nursing home residents: Feasibility and safety.

Introduction: Antibiotic resistant bacterial infections (ARBIs) are extremely common in nursing home residents. These infections typically occur after a course of antibiotics, which eradicate both pathological and beneficial organisms. The eradication of beneficial organisms likely facilitates subsequent ARBIs. Autologous fecal microbiota transplant (aFMT) has been proposed as a potential treatment to reduce ARBIs in nursing home residents. Our objective was to determine the feasibility and safety of aFMT in a nursing home population. Methods: Pilot clinical trial. We evaluated feasibility as total number of stool samples collected for aFMT production and safety as the number and relatedness of serious (SAE) and non-serious adverse events (AE). Results: We screened 468 nursing home residents aged ≥18 years for eligibility; 67 enrolled, distributed among three nursing homes. Participants were 62.7% female and 35.8% Black. Mean age was 82.2 ± 8.5 years. Thirty-three participants underwent successful stool collection. Seven participants received antibiotics; four participants underwent aFMT. There were 40 SAEs (17 deaths) and 11 AEs. In the aFMT group, there were 3 SAEs (2 deaths) and 10 AEs. All SAEs and AEs were judged unrelated to the study intervention. Conclusions: In this pilot study of aFMT in nursing home residents, less than half were able to provide adequate stool samples for aFMT. There were no related SAEs or AEs during the study. In sum, we conclude aFMT has limited feasibility in a nursing home population due to logistic and technical challenges but is likely safe. Trial registration: ClinicalTrials.gov Identifier: NCT03061097.

Fecal microbiota transplantation in HIV: A pilot placebo-controlled study.

Changes in the microbiota have been linked to persistent inflammation during treated HIV infection. In this pilot double-blind study, we study 30 HIV-infected subjects on antiretroviral therapy (ART) with a CD4/CD8 ratio < 1 randomized to either weekly fecal microbiota capsules or placebo for 8 weeks. Stool donors were rationally selected based on their microbiota signatures. We report that fecal microbiota transplantation (FMT) is safe, not related to severe adverse events, and attenuates HIV-associated dysbiosis. FMT elicits changes in gut microbiota structure, including significant increases in alpha diversity, and a mild and transient engraftment of donor's microbiota during the treatment period. The greater engraftment seems to be achieved by recent antibiotic use before FMT. The Lachnospiraceae and Ruminococcaceae families, which are typically depleted in people with HIV, are the taxa more robustly engrafted across time-points. In exploratory analyses, we describe a significant amelioration in the FMT group in intestinal fatty acid-binding protein (IFABP), a biomarker of intestinal damage that independently predicts mortality. Gut microbiota manipulation using a non-invasive and safe strategy of FMT delivery is feasible and deserves further investigation. Trial number: NCT03008941.

Shiga Toxin-Producing Escherichia coli Transmission via Fecal Microbiota Transplant.

Fecal microbiota transplantation (FMT) is recommended therapy for multiply recurrent Clostridioides difficile infection. We report adverse events in 7 patients who received FMT from a stool donor who was colonized with Shiga toxin-producing Escherichia coli (STEC). No patients died of FMT-transmitted STEC. Improved screening can likely avoid future transmission.

Modeling Donor Screening Strategies to Reduce the Risk of Severe Acute Respiratory Syndrome Coronavirus 2 Transmission via Fecal Microbiota Transplantation.

The potential for transmission of severe acute respiratory syndrome coronavirus 2 shed in stool via fecal microbiota transplantation is not yet known, and the effectiveness of various testing strategies to prevent fecal microbiota transplantation-based transmission has also not yet been quantified. In this study, we use a mathematical model to simulate the utility of different testing strategies.

Framework for rational donor selection in fecal microbiota transplant clinical trials.

Early clinical successes are driving enthusiasm for fecal microbiota transplantation (FMT), the transfer of healthy gut bacteria through whole stool, as emerging research is linking the microbiome to many different diseases. However, preliminary trials have yielded mixed results and suggest that heterogeneity in donor stool may play a role in patient response. Thus, clinical trials may fail because an ineffective donor was chosen rather than because FMT is not appropriate for the indication. Here, we describe a conceptual framework to guide rational donor selection to increase the likelihood that FMT clinical trials will succeed. We argue that the mechanism by which the microbiome is hypothesized to be associated with a given indication should inform how healthy donors are selected for FMT trials, categorizing these mechanisms into four disease models and presenting associated donor selection strategies. We next walk through examples based on previously published FMT trials and ongoing investigations to illustrate how donor selection might occur in practice. Finally, we show that typical FMT trials are not powered to discover individual taxa mediating patient responses, suggesting that clinicians should develop targeted hypotheses for retrospective analyses and design their clinical trials accordingly. Moving forward, developing and applying novel clinical trial design methodologies like rational donor selection will be necessary to ensure that FMT successfully translates into clinical impact.

Microbiome predictors of dysbiosis and VRE decolonization in patients with recurrent C. difficile infections in a multi-center retrospective study.

The gastrointestinal microbiome is intrinsically linked to the spread of antibiotic resistance. Antibiotic treatment puts patients at risk for colonization by opportunistic pathogens like vancomycin resistant Enterococcus and Clostridioides difficile by destroying the colonization resistance provided by the commensal microbiota. Once colonized, the host is at a much higher risk for infection by that pathogen. Furthermore, we know that microbiome community differences are associated with disease states, but we do not have a good understanding of how we can use these changes to classify different patient populations. To that end, we have performed a multicenter retrospective analysis on patients who received fecal microbiota transplants to treat recurrent Clostridioides difficile infection. We performed 16S rRNA gene sequencing on fecal samples collected as part of this study and used these data to develop a microbiome disruption index. Our microbiome disruption index is a simple index that is predictive across cohorts, indications, and batch effects. We are able to classify pre-fecal transplant vs post-fecal transplant samples in patients with recurrent C. difficile infection, and we are able to predict, using previously-published data from a cohort of patients receiving hematopoietic stem cell transplants, which patients would go on to develop bloodstream infections. Finally, we also identified patients in this cohort that were initially colonized with vancomycin resistant Enterococcus and that 92% (11/12) were decolonized after the transplant, but the microbiome disruption index was unable to predict such decolonization. We, however, were able to compare the relative abundance of different taxa between the two groups, and we found that increased abundance of Enterobacteriaceae predicts whether patients were colonized with vancomycin resistant Enterococcus. This work is an early step towards a better understanding of how microbiome predictors can be used to help improve patient care and patient outcomes.

Fecal Microbial Transplant Capsules Are Safe in Hepatic Encephalopathy: A Phase 1, Randomized, Placebo-Controlled Trial.

Hepatic encephalopathy (HE) can cause major morbidity despite standard of care (SOC; rifaximin/lactulose). Fecal microbial transplant (FMT) enemas postantibiotics are safe, but the effect of FMT without antibiotics using the capsular route requires investigation. The aim of this work was to determine the safety, tolerability, and impact on mucosal/stool microbiota and brain function in HE after capsular FMT in a randomized, single-blind, placebo-controlled clinical trial in Virginia. Patients with cirrhosis with recurrent HE with MELD (Model for End-Stage Liver Disease) <17 on SOC were randomized 1:1 into receiving 15 FMT capsules versus placebo from a single donor enriched in Lachnospiraceae and Ruminococcaceae. Endoscopies with duodenal and sigmoid biopsies, stool analysis, cognition, serum lipopolysaccharide-binding protein (LBP), and duodenal antimicrobial peptide (AMP) expression at baseline were used. Clinical follow-up with SOC maintenance was performed until 5 months. FMT-assigned patients underwent repeat endoscopies 4 weeks postenrollment. Twenty subjects on lactulose/rifaximin were randomized 1:1. MELD score was similar at baseline (9.6 vs. 10.2) and study end (10.2 vs. 10.5). Six patients in the placebo group required hospitalizations compared to 1 in FMT, which was deemed unrelated to FMT. Infection/HE episodes were similar between groups. Baseline microbial diversity was similar in all tissues between groups. Post-FMT, duodenal mucosal diversity (P = 0.01) increased with higher Ruminococcaceae and Bifidobacteriaceae and lower Streptococcaceae and Veillonellaceae. Reduction in Veillonellaceae were noted post-FMT in sigmoid (P = 0.04) and stool (P = 0.05). Duodenal E-cadherin (P = 0.03) and defensin alpha 5 (P = 0.03) increased whereas interleukin-6 (P = 0.02) and serum LBP (P = 0.009) reduced post-FMT. EncephalApp performance improved post-FMT only (P = 0.02). Conclusion: In this phase 1 study, oral FMT capsules are safe and well tolerated in patients with cirrhosis and recurrent HE. FMT was associated with improved duodenal mucosal diversity, dysbiosis, and AMP expression, reduced LBP, and improved EncephalApp performance. Further studies are needed to prove efficacy.

Correction to: Scaling Safe Access to Fecal Microbiota Transplantation: Past, Present, and Future.

In the original version of this article, author Ryan Elliott's name was misspelled as Ryan Eliott. The correct spelling of the name is Ryan Elliott.

Scaling Safe Access to Fecal Microbiota Transplantation: Past, Present, and Future.

PURPOSE OF REVIEW: Universal stool banks (USBs) have emerged as a potential model for scaling access to fecal microbiota transplantation (FMT) for Clostridium difficile infection (CDI). In this review, we outline the historical barriers constraining access to FMT, the evidence on methods and outcomes of USBs, and potential future directions for expanding access. RECENT FINDINGS: Key historical barriers to FMT access include regulatory uncertainty, operational complexity of sourcing screened donor material, and logistical challenges of delivering fresh treatment preparations. USBs have demonstrated that FMT can be delivered safely at scale by centralizing donor selection, material processing, and safety monitoring. More evidence is needed to optimize USB methods, including for donor screening, material processing, and novel delivery modalities. USBs have catalyzed broad access to FMT in North America and Europe. Future directions include developing evidence regarding oral preparations, harmonizing guidelines, disseminating best practice protocols, establishing long-term safety profiles, and expanding access to geographic areas of unmet need.