Modulation of the Gut Microbiota to Control Antimicrobial Resistance (AMR)-A Narrative Review with a Focus on Faecal Microbiota Transplantation (FMT)

Effect of Fecal Microbiota Transplant on Antibiotic Resistance Genes Among Patients with Chronic Pouchitis

BACKGROUND

Pouchitis is common among patients with ulcerative colitis (UC) who have had colectomy with ileal pouch-anal anastomosis. Antibiotics are first-line therapy for pouch inflammation, increasing the potential for gut colonization with multi-drug resistant organisms (MDRO). Fecal microbial transplant (FMT) is being studied in the treatment of pouchitis and in the eradication of MDRO. Prior work using aerobic antibiotic culture disks suggests that some patients with chronic pouchitis may regain fluoroquinolone sensitivity after FMT. However, gut MDRO include anaerobic, fastidious organisms that are difficult to culture using traditional methods.

AIM

We aimed to assess whether FMT reduced the abundance of antibiotic resistance genes (ARG) or affected resistome diversity, evenness, or richness in patients with chronic pouchitis.

METHODS

We collected clinical characteristics regarding infections and antibiotic exposures for 18 patients who had previously been enrolled in an observational study investigating FMT as a treatment for pouchitis. Twenty-six pre- and post-FMT stool samples were analyzed using FLASH (Finding Low Abundance Sequences by Hybridization), a CRISPR/Cas9-based shotgun metagenomic sequence enrichment technique that detects acquired and chromosomal bacterial ARGs. Wilcoxon rank sum tests were used to assess differences in clinical characteristics, ARG counts, resistome diversity and ARG richness, pre- and post-FMT.

RESULTS

All 13 of the patients with sufficient stool samples for analysis had recently received antibiotics for pouchitis prior to a single endoscopic FMT. Fecal microbiomes of all patients had evidence of multi-drug resistance genes and ESBL resistance genes at baseline; 62% encoded fluoroquinolone resistance genes. A numerical decrease in overall ARG counts was noted post-FMT, but no statistically significant differences were noted (P = 0.19). Richness and diversity were not significantly altered. Three patients developed infections during the 5-year follow-up period, none of which were associated with MDRO.

CONCLUSION

Antibiotic resistance genes are prevalent among antibiotic-exposed patients with chronic pouchitis. FMT led to a numerical decrease, but no statistically significant change in ARG, nor were there significant changes in the diversity, richness, or evenness of ARGs. Further investigations to improve FMT engraftment and to optimize FMT delivery in patients with inflammatory pouch disorders are warranted.

How can the gut microbiome be targeted to fight multidrug-resistant organisms?

The rise of antimicrobial resistance presents a challenge to public health, undermines the efficacy of antibiotics, and compromises the management of infectious diseases. Gut colonisation by multidrug-resistant organisms, such as multidrug-resistant Enterobacterales and vancomycin-resistant enterococci, is associated with increased morbidity and mortality rates, as well as health-care costs. Of late, the role of the gut microbiome in combating colonisation by multidrug-resistant organisms, which could precede invasive infection, has garnered interest. Innovative interventions, including faecal microbiota transplantation, probiotics, phage therapy, and bacterial consortia, represent potential preventive or therapeutic options to counteract colonisation by multidrug-resistant organisms. In this Personal View, we have synthesised the current findings on these interventions and elucidated their potential as solutions to the crisis of antimicrobial resistance.

Impact of a Purified Microbiome Therapeutic on Abundance of Antimicrobial Resistance Genes in Patients With Recurrent Clostridioides difficile Infection

BACKGROUND

The gastrointestinal microbiota is an important line of defense against colonization with antimicrobial resistant (AR) bacteria. In this post hoc analysis of the phase 3 ECOSPOR III trial, we assessed impact of a microbiota-based oral therapeutic (fecal microbiota spores, live; VOWST Oral Spores [VOS], formerly SER-109]; Seres Therapeutics) compared with placebo, on AR gene (ARG) abundance in patients with recurrent Clostridioides difficile infection (rCDI).

METHODS

Adults with rCDI were randomized to receive VOS or placebo orally for 3 days following standard-of-care antibiotics. ARG and taxonomic profiles were generated using whole metagenomic sequencing of stool at baseline and weeks 1, 2, 8, and 24 posttreatment.

RESULTS

Baseline (n = 151) and serial posttreatment stool samples collected through 24 weeks (total N = 472) from 182 patients (59.9% female; mean age: 65.5 years) in ECOSPOR III as well as 68 stool samples obtained at a single time point from a healthy cohort were analyzed. Baseline ARG abundance was similar between arms and significantly elevated versus the healthy cohort. By week 1, there was a greater decline in ARG abundance in VOS versus placebo (P = .003) in association with marked decline of Proteobacteria and repletion of spore-forming Firmicutes, as compared with baseline. We observed abundance of Proteobacteria and non-spore-forming Firmicutes were associated with ARG abundance, while spore-forming Firmicutes abundance was negatively associated.

CONCLUSIONS

This proof-of-concept analysis suggests that microbiome remodeling with Firmicutes spores may be a potential novel approach to reduce ARG colonization in the gastrointestinal tract.

Social and clinical predictors of perianal colonisation by multidrug-resistant bacteria for geriatric patients in the internal medicine service

BACKGROUND

Colonisation by multidrug-resistant (MDR) bacteria is a global health issue. The identification of patients with a higher risk of colonisation is essential. Patients admitted to internal medicine services might represent a vulnerable population with a high risk of colonisation. This study was the first to assess social and clinical variables associated with a higher risk of perianal colonisation by MDR bacteria in a Spanish cohort of patients admitted to internal medicine service.

METHODS

Patients admitted to an internal medicine service during 12 months of recruitment (1 March 2022 to 1 March 2023) were included in the study. Perianal swabs were performed at admission to identify the presence of MDR bacteria. Social and clinical variables were collected following a directed acyclic graph. A cluster analysis was performed to identify clinical profiles of higher risk. Bivariate analyses and multivariable logistic regression models were fitted to identify potential predictors of MDR bacteria colonisation.

RESULTS

A total of 245 patients, according to the required sample size, were included. Of them, 46 (18.8%) were colonised by MDR bacteria in perianal swabs. Female sex, age > 80 years, dependency on activities of daily living, cognitive deterioration and living in long-term care facilities constituted the highest risk clinical profile. After adjustments, living in long-term care facilities and malnutrition remained the main risk factors identified.

CONCLUSION

Patients admitted to internal medicine services presented a high frequency of perianal colonisation by MDR bacteria. Social and clinical variables associated with bio-psycho-social susceptibility were associated with colonisation. Special surveillance is needed in internal medicine services to control the transmission.

Pushing the frontiers in the fight against antimicrobial resistance: the potential of fecal and maggot therapies

The escalating crisis of antimicrobial resistance (AMR) warrants innovative therapeutic strategies. Fecal microbiota transplantation (FMT) and maggot debridement therapy (MDT) represent paradigm-shifting approaches, leveraging biological systems to mitigate AMR. FMT restores a healthy gut microbiome, providing a biotherapeutic counter to pathogenic bacteria, thereby reducing reliance on traditional antibiotics. Conversely, MDT, a form of bio-debridement, utilizes the antimicrobial secretions of maggots to cleanse wounds and eliminate resistant bacteria. Despite the promise these therapies hold, their broader clinical adoption faces multifaceted challenges including the need for rigorous scientific substantiation, standardized protocols, deepened understanding of mechanisms of action, and surmounting regulatory and public acceptance barriers. However, their potential integration with precision medicine could revolutionize disease management, particularly with antibiotic-resistant infections.

Decolonization of asymptomatic carriage of multi-drug resistant bacteria by bacteriophages?

Antimicrobial resistance is a major threat to human and animal health and accounted for up to 4.5 million deaths worldwide in 2019. Asymptomatic colonization of the digestive tract by multidrug resistant (multi-resistant) bacteria such as extended-spectrum beta-lactamase-, or carbapenemase- producing Enterobacterales is (i) a risk factor for infection by these multi-resistant bacteria, (ii) a risk factor of dissemination of these multi-resistant bacteria among patients and in the community, and (iii) allows the exchange of resistance genes between bacteria. Hence, decolonization or reduction of the gastrointestinal tract colonization of these multi-resistant bacteria needs to be urgently explored. Developing new non-antibiotic strategies to limit or eradicate multi-resistant bacteria carriage without globally disrupting the microbiota is considered a priority to fight against antibiotic resistance. Probiotics or Fecal Microbiota Transplantation are alternative strategies to antibiotics that have been considered to decolonize intestinal tract from MDR bacteria but there is currently no evidence demonstrating their efficacy. Lytic bacteriophages are viruses that kill bacteria and therefore could be considered as a promising strategy to combat antibiotic resistance. Successful decolonization by bacteriophages has already been observed clinically. Here, we discuss the current alternative strategies considered to decolonize the digestive tract of multidrug resistant bacteria, briefly describing probiotics and fecal microbiota transplantation approaches, and then detail the in vivo and in vitro studies using bacteriophages, while discussing their limits regarding the animal models used, the characteristics of phages used and their activity in regards of the gut anatomy.

Role of the gut microbiota in nutrient competition and protection against intestinal pathogen colonization

The human gut microbiota can restrict the growth of pathogens to prevent them from colonizing the intestine ('colonization resistance'). However, antibiotic treatment can kill members of the gut microbiota ('gut commensals') and reduce competition for nutrients, making these nutrients available to support the growth of pathogens. This disturbance can lead to the growth and expansion of pathogens within the intestine (including antibiotic-resistant pathogens), where these pathogens can exploit the absence of competitors and the nutrient-enriched gut environment. In this review, we discuss nutrient competition between the gut microbiota and pathogens. We also provide an overview of how nutrient competition can be harnessed to support the design of next-generation microbiome therapeutics to restrict the growth of pathogens and prevent the development of invasive infections.

Old Folks, Bad Boon: Antimicrobial Resistance in the Infant Gut Microbiome

The development of the intestinal microbiome in the neonate starts, mainly, at birth, when the infant receives its founding microbial inoculum from the mother. This microbiome contains genes conferring resistance to antibiotics since these are found in some of the microorganisms present in the intestine. Similarly to microbiota composition, the possession of antibiotic resistance genes is affected by different perinatal factors. Moreover, antibiotics are the most used drugs in early life, and the use of antibiotics in pediatrics covers a wide variety of possibilities and treatment options. The disruption in the early microbiota caused by antibiotics may be of great relevance, not just because it may limit colonization by beneficial microorganisms and increase that of potential pathogens, but also because it may increase the levels of antibiotic resistance genes. The increase in antibiotic-resistant microorganisms is one of the major public health threats that humanity has to face and, therefore, understanding the factors that determine the development of the resistome in early life is of relevance. Recent advancements in sequencing technologies have enabled the study of the microbiota and the resistome at unprecedent levels. These aspects are discussed in this review as well as some potential interventions aimed at reducing the possession of resistance genes.