Commonly used cancer drugs shown to boost MRSA antibiotics

This article has been reviewed according to Science X's editorial process and policies . Editors have highlighted the following attributes while ensuring the content's credibility: Dr. Aaron Nolan, postdoctoral researcher and lecturer in microbiology, Dr. Merve Zeden, assistant professor in microbiology, Professor James O'Gara, professor of microbiology, and Sarah Byrne, PhD researcher in microbiology, University of Galway. Credit: Andrew Downes, Xposure Scientists at University of Galway have uncovered a link between commonly used anticancer drugs and antibiotics that could offer a new approach to tackling superbug infections. The research team set out to find new ways to treat methicillin-resistant Staphylococcus aureus (MRSA) infections using drugs that are currently ineffective because of antibiotic resistance—a growing challenge in health care. MRSA is a type of S. aureus bacteria that has developed resistance to commonly used antibiotics, making infections more difficult to treat. The study, posted to bioRxiv, investigated whether a range of anticancer drugs could help penicillin-type antibiotics, which are among the most widely used antibiotics, become effective again. The research was carried out by Dr. Aaron Nolan, Sarah Byrne, Dr. Merve Zeden and Professor James O'Gara from the School of Biological and Chemical Sciences at University of Galway. The team tested five anticancer drugs and found that four of them (5-fluorouracil; 5-fluorouridine; gemcitabine; and mitomycin C) helped penicillin-type antibiotics kill MRSA. These drugs interfere with the bacteria's ability to make DNA, making them more vulnerable to antibiotics. A fifth anticancer drug that was tested (6-thioguanine) had the opposite effect and reduced the effectiveness of the antibiotics. Although this drug also affects DNA production in MRSA, it works differently, which may explain the difference in effects. Nolan, a postdoctoral researcher and lecturer in microbiology, explained, "We discovered several anticancer drugs that helped antibiotics to kill MRSA. But we also identified one anticancer drug that interfered with antibiotic effectiveness, highlighting the importance of carefully prescribing the most appropriate antibiotic for patients undergoing chemotherapy." Byrne, a Ph.D. researcher in microbiology, said, "The antibiotic resistance crisis is one of the world's most urgent health challenges. These findings are particularly important for patients with cancer who may need treatment for bacterial infections while also taking chemotherapy drugs." The findings also suggest that drugs already used to treat cancer could potentially be used alongside antibiotics to help them work against resistant bacteria. Zeden, an assistant professor of microbiology, said, "Our findings suggest that certain drugs originally developed for cancer treatment may have the potential to be repurposed alongside antibiotics. This could offer a new strategy to resensitize bacteria that have become resistant to existing treatments." The findings build on the team's ongoing research, which has identified the process of DNA production as a vulnerability in MRSA. By interfering with this process, some of the anticancer drugs tested in the study appear to make the bacteria more vulnerable to antibiotics. The discovery opens new avenues for research into combination therapies that pair antibiotics with nonantibiotic drugs. Such approaches could help extend the life span of existing antibiotics and provide new options for infections caused by bacteria resistant to traditional antibiotic treatments. O'Gara, a professor of microbiology at University of Galway, said, "We are excited by this discovery, which advances our long-term goal of finding new ways to boost the effectiveness of existing antibiotics against superbugs like MRSA. Because this approach relies on existing medications rather than developing completely new drugs, it could provide a faster route toward developing new strategies to improve patient care." Publication details Aaron C. Nolan et al, Purine and pyrimidine analogues differentially regulate cell wall precursor biosynthesis to control β-lactam susceptibility in methicillin resistant Staphylococcus aureus, bioRxiv (2026). DOI: 10.64898/2026.05.24.727567. Paper to be published in mBio: journals.asm.org/doi/10.1128/mbio.01274-26 Journal information: mBio , bioRxiv Key medical concepts MRSAFluorouracilGemcitabine