Commonly Used Antibiotic Linked to Emergence of Nearly Untreatable Superbug, Study Reveals

A new study has revealed that a commonly prescribed antibiotic for liver disease patients, rifaximin, could increase their risk of developing a dangerous superbug. The international research team found that rifaximin has contributed to the global rise of vancomycin-resistant Enterococcus faecium (VRE), a highly drug-resistant superbug that often causes severe infections in hospitalized patients.

The study, published in *Nature* on October 23, was led by researchers from the University of Melbourne’s Peter Doherty Institute for Infection and Immunity (Doherty Institute) and Austin Health. It revealed that rifaximin use is driving resistance to daptomycin, one of the few remaining effective treatments against VRE infections. These findings challenge the long-standing belief that rifaximin carries a “low risk” for causing antibiotic resistance.

Dr. Glen Carter, senior author and research fellow at the Doherty Institute, explained that rifaximin makes VRE resistant to daptomycin in an unprecedented way. The study found that rifaximin triggers changes in bacterial RNA polymerase, which activates a previously unknown gene cluster leading to cross-resistance to daptomycin.

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As reported by medicalxpress, the study has critical implications for clinicians, who are urged to exercise caution when treating VRE infections in patients using rifaximin, as daptomycin’s efficacy may be compromised. Lead investigator Associate Professor Jason Kwong emphasized the need for regulatory bodies to assess the “off-target” effects of antibiotics to prevent cross-resistance.

While rifaximin remains an effective treatment for liver disease patients, the findings underline the importance of careful antibiotic use to preserve vital last-resort treatments. The research highlights the need for genomics-based surveillance to monitor emerging antibiotic resistance and guide future clinical practice.

This study supports the recent call to action by world leaders at the UN General Assembly High-Level Meeting on Antimicrobial Resistance, where reducing the estimated 4.95 million annual deaths linked to antimicrobial resistance was a key objective.