Antibiotic resistance poses a serious threat especially for immunocompromised individuals who are more vulnerable to severe infections.

The composition of the gut microbiota plays a key role in preventing the spread of harmful bacteria a phenomenon known as the barrier effect. To restore this protective function researchers are developing targeted therapies using beneficial microbes.

In this study INRAE scientists investigated vancomycin-resistant enterococci one of six high-priority multidrug-resistant pathogens identified by the World Health Organization. Their goal was to pinpoint the bacteria contributing to the barrier effect and demonstrate their potential to stop the growth of these dangerous pathogens paving the way for new therapeutic strategies.

Researchers collected microbiota samples from mice that had been orally exposed to enterococci. Through mathematical modeling they identified seven out of over 500 bacterial species that appeared to have a barrier effect the greater their presence the fewer pathogenic bacteria were observed.

To test the effectiveness of these seven bacteria scientists compared mice treated with antibiotics and infected with VRE with and without the bacterial mixture. They found that mice receiving the mixture showed reduced levels of pathogenic bacteria.

However, the response varied between individual mice underscoring the influence of each host's original microbiota similar to what is seen in humans. Lab tests revealed that the seven bacteria alone could not suppress pathogen growth in vitro suggesting that their efficacy relies on interactions with the host's native microbiota.

In addition to deepening their understanding of bacteria’s anti-proliferative effects and underlying mechanisms the scientists now aim to build a comprehensive collection of microorganisms from the human microbiota to explore potential clinical applications.

Pursuing a personalized medicine approach the researchers are also developing predictive biomarkers. This involves analyzing the bacterial composition of a patient’s microbiota to predict the likelihood of treatment success or to tailor the bacterial therapy to the individual’s needs.

Source: https://www.inrae.fr/en/news/using-bacteria-improve-microbiota-resistance-pathogens