What is already known
Fecal microbiota transplant (FMT) is effective to treat people with recurrent Clostridioides difficile infection. The practice may also help to keep intestinal antimicrobial-resistant organisms at bay. However, safety concerns and inconclusive evidence about the efficacy of FMT have limited its application. Microbial consortia — combinations of bacterial strains isolated from healthy human donors — have been developed to overcome some limitations of FMT. But their efficacy in removing pathogens and antibiotic-resistant organisms from the gut remains unclear.
What this research adds
Researchers analyzed stool samples collected from previous studies that looked at microbial consortia and FMT for treating recurrent Clostridioides difficile infection. A microbial consortium called MET-2 had similar effects to FMT on microbiota outcomes, including a reduction in antibiotic-resistant organisms. Compared with FMT, treatment with MET-2 was also associated with a greater decrease in Pseudomonadota/Proteobacteria, which include a wide variety of pathogenic bacteria such as Escherichia, Salmonella and Legionella. The beneficial outcomes remained stable for more than 4 months after treatment.
Conclusions
The findings suggest that microbial consortia such as MET-2 may be effective strategies to keep intestinal pathogens and antibiotic-resistant organisms at bay.
The overgrowth of gut bacteria that are resistant to antimicrobial drugs poses a high risk of infection, especially in hospitalized people. Now, researchers have found that mixtures of bacteria isolated from healthy donors may help keep intestinal pathogens and antibiotic-resistant organisms at bay.
The findings, published in mBio, support clinical trials to test the efficacy of microbial consortia.
These consortia — combinations of bacterial strains isolated from healthy human donors — have been developed to overcome some limitations of fecal microbiota transplant (FMT). Although FMT has proved effective in treating people with recurrent Clostridioides difficile infection and reducing gut colonization with antimicrobial-resistant organisms, safety concerns and inconclusive evidence about the efficacy of the procedure have limited its application.
However, whether microbial consortia are effective in removing pathogens and antibiotic-resistant organisms from the gut remains unclear. To address this question, Ashley Rooney at the University of Toronto in Canada and her colleagues analyzed stool samples collected from previous studies that looked at microbial consortia and FMT for treating infection with Clostridioides difficile.
Beneficial outcomes
The researchers assessed 19 people with recurrent Clostridioides difficile infection who participated in an evaluation of the effects of either FMT or a microbial consortium called MET-2. Participants were included in the current study if their baseline stool abundance of Pseudomonadota/Proteobacteria was greater than 10%. Pseudomonadota encompass a wide variety of pathogenic bacteria such as Escherichia, Salmonella and Legionella.
At baseline, the most abundant Pseudomonadota in both groups were Klebsiella, Escherichia coli, Enterobacter cloacae and Citrobacter, and the numbers of antibiotic-resistant bacteria were similar between the groups.
One month after treatment, people who received MET-2 had similar microbiota outcomes to those who received FMT. These outcomes included an overall decrease in the total number of antibiotic-resistant genes and an increase in butyrate-producing bacteria, which have been associated with beneficial effects on human health.
Lasting benefits
Compared with FMT, treatment with MET-2 was also associated with a greater decrease in Pseudomonadota. One month after intervention, the abundance of Pseudomonadota decreased to about 0.01% in people who received MET-2 and to 2.2% in those who received FMT.
In both groups, the beneficial outcomes remained stable for more than 4 months after treatment, the researchers found.
“Administration of a microbial consortium for [recurrent Clostridioides difficile infection] in participants colonized with a high relative abundance of potential pathogens has similar effects to FMT for decreasing intestinal Pseudomonadota and [antimicrobial resistance genes],” the authors say.
“Given the practical limitations and potential safety concerns of FMT, a trial of microbial consortia for pathogen and [antimicrobial resistance genes] decolonization is warranted.”
