Summary: Studying the effects of the microbiome on the liver is critical to human health. The liver is the second most directly affected organ after the gut by the composition of the gut microbiome. In addition, liver transplantation has a higher rate of infection, which is related to the gut microbiome. Many liver transplant patients carry multidrug-resistant bacteria that are associated with reduced gut microbiome diversity.
The latest study analyzed stool samples from more than 100 patients who underwent liver transplants to determine whether the microbiome influenced their risk of postoperative infection. By quantifying fecal metabolites in 107 patients who underwent liver transplantation, the researchers were able to correlate them with fecal microbial composition, pathogenic microbial expansion, and postoperative infection. By analyzing the fecal microbiome, they were able to successfully assess the risk of postoperative infection in liver transplant patients.
The study, published in the journal Cell Host & Microbe, is titled "Fecal Metabolite Analysis Identifies Postoperative Infection Risk in Liver Transplant Patients."
Dr. Christopher Lehmann, an assistant professor of medicine at the University of Chicago, said: "Antibiotic resistance is growing and getting worse every year. Without effective antibiotics, we cannot perform surgery, protect premature babies or **cancer. "The human microbiome, especially the gut microbiome, has evolved over a long history of adapting to fight drug-resistant bacteria," he said. We need to do our best to understand how it fights these drug-resistant infections. ”
Studies have found that a healthy microbiome produces a variety of key metabolites, including short-chain fatty acids that are beneficial to the human body, and secondary bile acids that bacteria produce when they modify human bile acids to suit their own needs. Some of these bile acids are highly toxic to bacteria, such as vancomycin-resistant enterococci (VRE), an antibiotic-resistant bacterium that often causes infections in surgery, cancer**, or intensive care patients.
The researchers used data analysis to find out if there was an association between microbial composition and postoperative infection. "The number of drug-resistant pathogens in the microbiome** post-infection has been shown to be as accurate as what we typically look for in clinical tests," said Dr. Lehmann. The team then analyzed only the metabolites in the sample to see if they had the same value. Scientists have found that they can use metabolites to determine whether a patient will be infected.
Specifically, the study authors wrote: "Whereas experimental studies have shown that metabolites produced by the microbiome are associated with host-mediated antimicrobial defenses, reducing fecal concentrations of short- and branched-chain fatty acids, secondary bile acids, and tryptophan metabolites in liver transplant patients are associated with the relative risk of microbiome dysregulation and postoperative infection." ”
Dr. Lehmann noted, "We can learn directly from metabolites** clinical results. This is important because metabolomics analysis can be performed very quickly, while sequencing is comparatively slow. ”
At present, the analysis algorithm is too complex to be used for diagnosis or testing in clinical practice. However, these findings lay the groundwork for future studies that may strengthen the link between infections and metabolites in stool samples, as well as explore potential causal relationships.
"The next step in this research will be to investigate whether we can use these findings to correct people's microbiomes," Dr. Lehmann said. "Patients with an unhealthy, single-species gut microbiome and at higher risk of infection may be able to accept healthy gut bacteria from the outside** and resume production of healthy metabolites, including molecules such as secondary bile acids that can help fight drug-resistant infections.
In 2023, the FDA approved two microbiome remediation products. "Microbiome repair is not in the distant future;It is already a reality. "The Division of Biological Sciences at the University of Chicago has established a biobank containing thousands of species of bacteria, all of which have been analyzed and classified according to their genomes and the metabolites they produce. The University of Chicago is also building a GMP-compliant facility that will allow scientists to produce, filter and freeze-dry key gut bacteria extracted from healthy donors and fill them into pharmaceutical-grade capsules that patients can take as if they were pills.
Reference: "Fecal metabolite profiling identifies liver transplant recipients at risk for postoperative infection."”
Editor: Zhou Min.
Typesetting: Li Li.