Scientists at Cold Spring Harbor Laboratory and Scripps Research have found a way to restore the killing power of vancomycin, one of medicine's last-resort antibiotics, against bacteria that had evolved resistance to it. The approach does not involve creating a new antibiotic. Instead, it targets a bacterial enzyme called secreted antigen A, or SagA, using a small molecule called pghi-4, effectively disabling the mechanism bacteria use to evade vancomycin.
When vancomycin and pghi-4 were combined in laboratory experiments, vancomycin's ability to kill vancomycin-resistant Enterococcus faecium, or VREfm, was restored. The required dose of vancomycin dropped by up to eightfold. The findings, published in Nature Communications on June 16, 2026, were highlighted this week in a CSHL press release drawing renewed attention to the work.
Why This Matters
Antibiotic resistance is one of the most urgent threats to global health. Drug-resistant bacteria were linked to an estimated 4.7 million deaths worldwide in 2019 alone, according to a widely cited analysis, and the toll has grown since then. Vancomycin has long served as a critical last-resort antibiotic for serious infections that cannot be treated with other drugs. As more bacteria have evolved resistance to it, the medical community has been left with progressively narrower options for the most severe, life-threatening infections.
VREfm is a particularly dangerous pathogen. It can cause bloodstream infections, endocarditis, urinary tract infections, and wound infections, especially in patients in intensive care units, transplant recipients, and cancer patients whose immune systems are compromised. The rise of vancomycin-resistant strains means that some of these patients currently have no effective antibiotic option. A strategy that restores vancomycin's effectiveness, even partially, could have immediate implications for hospital infection management.
What We Know So Far
The research was led by Professor John Moses at Cold Spring Harbor Laboratory and Professor Howard Hang at Scripps Research. The key insight came from an earlier discovery in Moses's laboratory in 2020, when pghi-4, a compound from a class called beta-chloroalkenyl sulfonyl fluorides, was first synthesized. The team later identified pghi-4 as an inhibitor of SagA, an enzyme that plays a central role in remodeling the bacterial cell wall, the very structure that vancomycin targets.
When bacteria such as VREfm express SagA, it modifies the cell wall in ways that prevent vancomycin from binding effectively. By blocking SagA with pghi-4, the researchers exposed the binding site again, allowing vancomycin to attach and kill the bacteria. The combination reduced the amount of vancomycin needed to kill VREfm by up to eightfold across multiple clinical isolates and also reduced the bacterial burden in a mouse model of sepsis, a particularly lethal systemic infection.
Critically, deleting SagA had little impact on the bacteria's resistance to other antibiotics, including ampicillin, daptomycin, and ceftriaxone. This suggested the mechanism is specifically targeting the vancomycin resistance pathway rather than broadly weakening the bacteria, which is clinically important because broad bacterial weakening could cause unpredictable off-target effects.
Where the Impact Is Highest
Hospital patients in intensive care units, surgical wards, and oncology centers bear the heaviest burden from VREfm infections. Major academic medical centers in cities such as New York, Los Angeles, Chicago, Houston, and Boston routinely manage VREfm infections and are most likely to be early adopters of any new clinical strategy that emerges from this research.
The strategy is part of a growing category called antibiotic adjuvants, compounds that do not kill bacteria themselves but restore the effectiveness of existing antibiotics by disabling bacterial resistance mechanisms. This approach is attractive because it avoids the lengthy and expensive process of developing entirely new antibiotic classes, working instead to extend the useful life of drugs already well understood by clinicians and regulators.
What Doctors and Experts Say
"This discovery came from fundamental chemical research," said John Moses of Cold Spring Harbor Laboratory. "Reaction development led to the discovery of the first inhibitor of an important enzyme involved in antibiotic resistance. This is a process we're constantly refining." Moses characterized the findings as important not just for vancomycin and VREfm specifically, but as a proof of concept that targeting bacterial cell-wall remodeling enzymes, a class that no drug had ever successfully inhibited before, can overcome antibiotic resistance.
Howard Hang of Scripps Research noted that the same strategy could eventually be extended to other resistant pathogens, including tuberculosis and drug-resistant Staphylococcus aureus. "To demonstrate you can pharmacologically target this enzyme family is a big step forward," Hang told EurekAlert. The broader lesson, he said, is that targeting fundamental aspects of bacterial physiology can overcome resistance in ways that the bacteria have not evolved defenses against.
What the Evidence Shows and What It Does Not
The Nature Communications study established the mechanism by which SagA inhibition restores vancomycin sensitivity in VREfm, confirmed this in multiple clinical isolates of the bacteria, and validated the approach in a mouse model of sepsis. These are preclinical findings. The research has not yet been tested in humans, and there is no timeline for clinical trials or regulatory application. The path from a mouse model to a human drug typically involves years of additional safety and efficacy testing.
MedicalDaily Evidence Check
The study is a preclinical laboratory and animal study published in peer-reviewed Nature Communications on June 16, 2026 (DOI: 10.1038/s41467-026-74057-1), conducted by researchers at Cold Spring Harbor Laboratory and Scripps Research.
The research found that the small molecule pghi-4 inhibited the bacterial enzyme SagA and restored vancomycin's ability to kill VREfm in cell culture and in a mouse model of sepsis, reducing the dose of vancomycin needed by up to eightfold across multiple clinical isolates.
What the study did not prove is that this approach is safe or effective in humans, as no clinical trials have been conducted. Readers should know that this is a promising early-stage finding and not an available treatment; the development of pghi-4 into a clinical drug would require years of additional research and regulatory review.
Who Faces the Greatest Risk Without New Options
Hospital patients with the following profiles face the highest risk from VREfm: those receiving bone marrow or solid organ transplants, patients in intensive care units with central venous lines, people undergoing chemotherapy, individuals with compromised immune systems from HIV or autoimmune treatment, and patients who have received prolonged courses of antibiotics that disrupt the gut microbiome and allow VREfm colonization. In these populations, a blood or wound infection with a vancomycin-resistant strain currently leaves clinicians with only a small number of last-resort alternatives, including daptomycin and linezolid, both of which also face emerging resistance.
Symptoms and Warning Signs to Watch For
VREfm infections typically develop in hospitalized patients rather than in otherwise healthy community members. Warning signs in hospitalized patients include new fever, chills, or rigors, unexpected blood pressure changes, wound redness, swelling or discharge that does not improve with initial antibiotics, and urinary symptoms in catheterized patients. Family members of patients hospitalized with serious infections should ask their care team whether infection control precautions are in place and whether antibiotic susceptibility testing has been performed.
For the general public, the most effective protection against drug-resistant hospital infections remains preventing unnecessary hospitalization when possible, ensuring that prescribed antibiotic courses are completed as directed, and avoiding demanding antibiotic prescriptions for viral infections such as colds and flu.
What You Can Do Now
Patients and family members who are concerned about antibiotic-resistant infections in a hospital setting should speak directly with the treating physician or the hospital's infectious disease team. Asking about antibiotic susceptibility testing results, whether infection control precautions are appropriate, and what options remain if initial antibiotics fail is not only appropriate but recommended. Hospital infection control programs at accredited facilities maintain policies for VREfm management and contact precautions.
For patients with planned hospitalizations or surgeries, discussing preoperative decolonization protocols with a physician is a reasonable step at facilities where this is offered. The CDC's antibiotic resistance website provides additional public guidance on preventing and responding to drug-resistant infections.
Cost and Access: What Patients Should Know
Pghi-4 is not available as a clinical treatment and has no commercial development pathway yet confirmed. If clinical development proceeds, it would be classified as a new drug requiring FDA approval with an accompanying cost structure. For current patients with VREfm infections, treatment involves existing approved options including daptomycin, linezolid, and in some cases newer agents such as oritavancin or dalbavancin, all of which are hospital-administered drugs covered by inpatient insurance benefits for eligible patients.
What Happens Next
The research teams at Cold Spring Harbor Laboratory and Scripps are developing more potent second-generation derivatives of pghi-4 and exploring whether the same strategy can be applied to other resistant pathogens. The researchers believe the approach could be extended to combinations involving tuberculosis-causing bacteria and drug-resistant Staphylococcus aureus, both of which represent major global health burdens. MedicalDaily will report on clinical development milestones as they are announced.
The Bottom Line
The restoration of vancomycin's effectiveness against drug-resistant bacteria using a small molecule inhibitor represents a genuinely promising early-stage research finding in the fight against antibiotic resistance. The approach is elegant precisely because it works with an existing, well-understood drug rather than requiring the development of a new antibiotic class. But it remains years away from clinical application. The immediate value of this research is the scientific proof of concept that disabling bacterial resistance enzymes can restore antibiotic effectiveness, opening a new strategic direction in the ongoing effort to stay ahead of superbugs.
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