Researchers from the Department of Life Sciences have discovered how antibiotic use alters the gut environment creating conditions that favour colonisation by vancomycin-resistant enterococci (VRE) pathogens linked to severe hard-to-treat infections. Published in Nature Communications the findings could guide the development of next-generation microbiome therapies to prevent such infections before they take hold.

VRE are a leading cause of hospital-acquired infections including bloodstream urinary tract and heart valve infections, with gut colonisation often occurring before invasive disease develops.

Led by Dr. Julie McDonald from Imperial’s Department of Life Sciences and Centre for Bacterial Resistance Biology, the team discovered that antibiotics can inadvertently make the gut more hospitable to opportunistic pathogens by disrupting the protective gut microbiota that normally suppresses harmful bacteria. In a healthy gut beneficial microbes compete for nutrients and produce short-chain fatty acids natural antibiotic-like compounds that restrict VRE growth but these defences are weakened or lost after antibiotic treatment. The researchers found that while individual short-chain fatty acids had limited effect combinations could completely block VRE growth in lab experiments. Antibiotics also eliminated beneficial bacteria that typically consume a wide range of nutrients leaving these resources more abundant for VRE to exploit. Furthermore, the study showed that VRE occupy distinct niches in the gut separate from other drug-resistant pathogens such as carbapenem-resistant Enterobacteriaceae (CRE), underscoring the need for pathogen-specific therapeutic strategies.

The study’s findings open the door to new microbiome-based strategies for preventing infections, such as probiotic blends that restore protective gut bacteria and reduce nutrients available to VRE or metabolite-based supplements administered alongside antibiotics to suppress harmful bacteria. Dr. Julie McDonald explained that these insights provide a foundation for developing targeted therapeutics to re-establish a healthy gut environment that limits VRE growth thereby removing a major reservoir for the pathogen and reducing the risk of difficult-to-treat infections. The work was carried out in collaboration with researchers across Imperial, including Dr. Thomas Clarke (Department of Infectious Disease) Dr. Benjamin Mullish, and Professor Julian Marchesi (Department of Metabolism, Digestion and Reproduction) who contributed to key experiments involving mouse models, human faecal sample collection, and sequencing.

Source: https://www.imperial.ac.uk/news/267313/gut-bacteria-could-help-block-rise/