Diabetes mellitus, hypertension, cardiovascular diseases... Drugs have shown their limitations in the treatment of these diseases that are associated to excess weight and sedentary lifestyle.
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In animals, the physical trait “obese” or “thin” can be transferred through fecal microbiota transplant with a clearly established causal link. In humans, the situation is a little more complex but the presence of dysbiosis associated to metabolic disorders in obese or hypertensive subjects led scientists to conclude that FMT could be a promising avenue. Works are ongoing to assess the impact of the change in gut microbiota experienced by patients with metabolic syndrome17,14.
Several clinical studies were conducted on obese patients with a metabolic syndrome. The first one was carried out on a small group of individuals and showed that stool transplant from thin donors improved the metabolic profile of recipients. The second included a larger number of patients and produced more mixed results. Only a few participants had an improved metabolic profile after the FMT, namely those who initially had a gut microbiota that was not very diversified. The response to transplant thus seems to be dependent on the patient’s initial gut microbiota. However, the benefits did not withstand the test of time...nor did the transformation of the gut microbiota, which quickly returned to its initial composition.
Overall, these results highlight the complexity of the link between the gut microbiota and metabolic functions. According to some scientists13, metabolic and microbial responses to FMT could be based on interactions between the donor’s microbiota and the recipient’s. Several trials are ongoing to assess this technique’s ability to reduce metabolic disorders as well as several obesity-related parameters. These eagerly awaited results should open the way to new strategic approaches in the treatment of metabolic syndrome.
STOOL TRANSPLANT: A PROMISING SOLUTION AGAINST ANTIBIOTIC RESISTANCE?
- Antibiotic resistance keeps growing as a result of gut’s colonization by microorganisms which have become insensitive to antibiotics. Could the solution be a fecal microbiota transplant? Several studies support this hypothesis19.
By triggering a competition within the gut microbiota, FMT leads to the decolonization of several bacteria that are resistant to different antibiotic families (Escherichia coli resistant to cephalosporins, Enterococcus resistant to vancomycin, o enterobacteria resistant to carbapenems). In a clinical trial comparing antibiotic therapy followed by FMT with no intervention at all, the former was more successful (41% of patients were “decolonized” vs. 29% respectively)20.
In two prospective studies where FMT was used–in one by itself and in the other together with an antibiotic pretreatment–it proved twice as much successful (up to 88%) to reduce populations of resistant bacteria8.
If ongoing trials, including a larger number of patients, confirmed these excellent results, FMT could contribute to solving a major health scourge.
13 Maladies inflammatoires chroniques de l’Intestin (MICI). Inserm. Fév. 2016
17 Metabolic syndrome, or syndrome X, refers to a cluster of physiological and biochemical disorders of lipid, carbohydrate or vascular origin associated to excess weight (French Federation of Cardiology)
20 Huttner BD, et al. A five-day course of oral antibiotics followed by faecal transplantation to eradicate carriage of multidrugresistant Enterobacteriaceae: A Randomized Clinical Trial. Clin Microbiol Infect. 2019