The article published in Nature, titled “Rifaximin Prophylaxis Causes Resistance to the Last-Resort Antibiotic Daptomycin,” reveals critical findings regarding the use of rifaximin and its impact on antibiotic resistance, particularly concerning the last-resort antibiotic daptomycin. This study suggests that the use of rifaximin, commonly administered to prevent hepatic encephalopathy in patients with liver disease, may inadvertently contribute to the emergence of resistance against daptomycin.

Key Findings:

Rifaximin, a commonly prescribed antibiotic for liver disease, has been found to cause resistance to daptomycin. This is a critical finding as daptomycin is considered a last-resort antibiotic for treating infections caused by vancomycin-resistant enterococcus faecium (VRE), a dangerous superbug.

This is the first recorded instance of one antibiotic causing resistance to another in a different class. Previously, it was believed that antibiotic resistance was limited to the specific antibiotic being used.

Rifaximin was previously considered a “low risk” antibiotic in terms of resistance development. This study challenges that assumption and highlights the unexpected consequences of antibiotic use.

Specific mutations in the rpoB gene of VRE are responsible for this cross-resistance. These mutations are becoming increasingly prevalent globally, coinciding with the increased use of rifaximin.

Rifaximin exposure leads to the upregulation of the prdRAB operon in VRE. It results in cell membrane changes that reduce daptomycin binding and efficacy. This newly identified mechanism is independent of previously known daptomycin resistance mechanisms.

This research highlights the unintended consequences of using rifaximin prophylactically. Notably, its role in promoting resistance to critical antibiotics like daptomycin. Such findings carry significant implications for public health and antibiotic stewardship, highlighting the urgent need for careful management of antibiotic use to reduce the development of antibiotic resistance. The interplay between rifaximin and daptomycin resistance emphasizes the importance of ongoing monitoring and evaluation of antibiotic prescribing practices.