Gut Microbiome (IMAGE) University of Pennsylvania School of Medicine Caption The antibiotic vancomycin alters the gut microbiome in a way that can help prime the immune system to more effectively attack tumor cells after radiation therapy. Credit Penn Medicine Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.