New Antibiotic EVG7 Targets Deadly Gut Infection While Sparing Microbiome

Researchers at Leiden University have developed a new antibiotic that can combat the dangerous gut bacterium C. difficile using a much smaller dose than current treatments — and it appears to spare the beneficial bacteria that help prevent the infection from returning.

The experimental drug, called EVG7, is a more potent version of the widely used antibiotic vancomycin. In mouse studies, even a low dose cleared the infection and dramatically reduced relapse rates, according to findings published in Nature Communications.

"With existing antibiotics, C. difficile sometimes reappears just weeks after treatment," said Elma Mons, lead author and researcher at the Institute of Biology Leiden. "This happens partly because the bacterium leaves behind spores that can later grow into new bacteria."

The key difference: mice treated with a low dose of EVG7 retained far more beneficial bacteria from the Lachnospiraceae family, which naturally protect against C. difficile. Standard antibiotics often wipe out these protective microbes along with the pathogen, allowing residual spores to germinate and trigger a new infection.

"That's the approach doctors are increasingly taking — preserving the microbiome whenever possible," Mons said.

The research also found EVG7 doesn't appear to trigger antibiotic resistance even at lower doses, since it still kills the bacteria completely rather than merely irritating them.