Erstwhile Most Powerful Antibiotic Vancomycin’s Just Got Revived Against Resistance: Here’s How

• Scientists found a way to restore vancomycin’s effectiveness against resistant bacteria.
• A small molecule blocks a key bacterial defense, allowing the antibiotic to work again.
• The approach could help fight dangerous antibiotic-resistant infections.
• The discovery is still in the laboratory stage and needs further testing.

Scientists at Cold Spring Harbor Laboratory (CSHL) and Scripps Research have discovered a way to make vancomycin, one of the world’s most important last-resort antibiotics, work again against bacteria that had become resistant to it. The study, published on July 22, 2026, in Nature Communications, found that combining vancomycin with a small molecule called pghi-4 removes one of the bacteria’s key defenses, allowing the antibiotic to kill them once more.

Vancomycin has been used since the 1950s and is often reserved for treating serious infections when other antibiotics no longer work. Over time, however, some bacteria, especially vancomycin-resistant Enterococcus faecium (VRE), a common cause of hospital-acquired infections, have evolved ways to survive the drug.

Instead of trying to develop an entirely new antibiotic, the researchers focused on restoring the effectiveness of an existing one. Their experiments showed that pghi-4 blocks a resistance mechanism used by the bacteria, enabling vancomycin to work against infections that had previously become difficult to treat.

This approach could offer a faster and potentially more practical way to combat antibiotic resistance by extending the life of medicines that are already available.

How the Resistance Was Broken

Drug-resistant Enterococcus faecium survives vancomycin by using an enzyme called SagA (secreted antigen A) to remodel its cell wall so the antibiotic can no longer attack it.

The CSHL team, led by Professor John Moses, identified pghi-4 as a molecule that binds directly to SagA and blocks its activity. When the enzyme is disabled, the bacterial cell wall returns to a form that vancomycin can attack. In laboratory experiments, combining vancomycin with pghi-4 successfully killed drug-resistant E. faecium that survived treatment with vancomycin alone.

The molecule pghi-4 was not originally designed to overcome antibiotic resistance. It was first synthesized in the Moses laboratory in 2020 using a technique called diversity-oriented clicking (DOC), which rapidly generates large libraries of new chemical compounds. That collection now contains more than 150 molecules, several of which have already contributed to research into antibiotic resistance and cancer.

The collaboration with Professor Howard Hang’s laboratory at Scripps Research ultimately identified pghi-4’s ability to overcome vancomycin resistance, a discovery that emerged from basic chemistry research rather than a targeted search for a new antibiotic.

What Moses Says About the Bigger Picture

Professor Moses said the discovery emerged from fundamental chemistry research rather than a project specifically aimed at developing a new antibiotic treatment. “This discovery came from fundamental chemical research. Reaction development led to the discovery of the first inhibitor of an important enzyme involved in antibiotic resistance.”

He said the study demonstrates how advances in chemistry can speed up the search for new medicines.

“This work reflects a philosophy of chemistry that’s designed to accelerate drug discovery in its purest form. By using reliable, robust, and intelligent chemical reactions, we can build new molecules more efficiently. That’s exactly the approach we used here.”

Why This Approach Could Be Bigger Than One Antibiotic

What makes the pghi-4 finding important is the broader strategy it represents, not simply the rescue of vancomycin. Antibiotic adjuvants, compounds that do not kill bacteria directly but restore the effectiveness of existing antibiotics, are increasingly viewed as one of the most promising ways to combat antimicrobial resistance.

Developing an entirely new antibiotic typically takes 10 to 15 years and costs more than $1 billion. Finding compounds that revive drugs already approved for medical use could dramatically shorten that process.

The urgency is considerable. According to the World Health Organization, antimicrobial resistance contributed to 1.27 million deaths worldwide in 2019. Without effective interventions, resistant infections could cause 10 million deaths annually by 2050, surpassing cancer as a leading cause of death. Vancomycin-resistant Enterococcus faecium is classified by the WHO as a high-priority pathogen requiring new treatment options.

Researchers believe the DOC chemical library may also yield compounds capable of restoring antibiotic effectiveness against other dangerous pathogens, including drug-resistant tuberculosis.

What Happens Next

The research has so far been conducted only in laboratory cell cultures. The vancomycin-pghi-4 combination has not yet been tested in animals or humans, and clinical trials remain years away.

Even so, identifying SagA as a druggable target and demonstrating that pghi-4 can disable it provides researchers with a validated starting point for developing therapies that restore the effectiveness of existing antibiotics against resistant bacteria.