🩹 A bacteria that prevents wound healing

The treatment of chronic wounds represents a major public health challenge, starting with diabetic foot ulcers which affect approximately 18.6 million people worldwide each year.

A team from the University of Geneva (UNIGE) and Nanyang Technological University (NTU) in Singapore shows how a common pathogen, Enterococcus faecalis, actively prevents healing, and how neutralizing this process - by blocking the harmful products this bacterium generates - can allow skin cells to regenerate and close wounds. These results are published in Science Advances.


Often worsened by persistent infections, chronic wounds are slow to heal, especially in people with diabetes whose hyperglycemia slows healing. This type of wound is thus one of the leading causes of lower limb amputation.

In a recent study, a team from UNIGE and NTU in Singapore reveals how a very widespread opportunistic bacterium, Enterococcus faecalis, actively blocks tissue repair. The scientists also show that by neutralizing this mechanism, it is possible to restore the ability of skin cells to regenerate, thereby reducing the risks of complications and amputation.

Co-led by Guillaume Thibault, associate professor at the NTU School of Biological Sciences, and Kimberly Kline, full professor in the Department of Microbiology and Molecular Medicine at the UNIGE Faculty of Medicine and a member of SCELSE - Singapore Centre for Environmental Life Sciences and Engineering, the team discovered that the bacterium does not use a classic toxin to disrupt healing, but hijacks a product of its own metabolism.

"E. faecalis uses a metabolic process not previously recognized, called extracellular electron transfer (EET), which continuously produces hydrogen peroxide, a reactive oxygen species particularly aggressive to living tissues," explains Aaron Tan, a researcher at SCELSE and first author of the study.

Oxidative stress that paralyzes skin cells

Hydrogen peroxide, commonly used as an industrial disinfectant and bleaching agent, becomes problematic when it is generated directly within an infected wound. The scientists showed that this compound, produced by the bacterium, induces significant oxidative stress in keratinocytes — the cells responsible for skin repair. This stress activates a cellular defense mechanism linked to misfolded proteins, which ultimately paralyzes the cells and prevents them from migrating to close the wound.

To confirm the central role of this process, the scientists used a genetically modified strain of E. faecalis lacking the EET pathway. Result: the production of hydrogen peroxide was greatly reduced and the bacterium was no longer able to block healing.

The team then assessed whether neutralizing the hydrogen peroxide could reverse the damage. By treating the skin cells with catalase — an antioxidant enzyme naturally present in the body and capable of degrading hydrogen peroxide — they reduced cellular stress and restored the cells' ability to migrate and repair tissue.

Toward new therapeutic approaches

"Our results show that it is the bacterium's own metabolism that constitutes the weapon, a surprising and previously unknown discovery," emphasizes Guillaume Thibault. "Rather than trying to eliminate the bacterium with antibiotics — an increasingly difficult strategy that promotes resistance — we can now consider neutralizing the harmful products it generates and thus restore healing."

The study establishes a direct link between bacterial metabolism and host cell dysfunction, paving the way for new therapeutic strategies for chronic wounds. It notably suggests that dressings enriched with antioxidants, such as catalase, could constitute a promising approach. These results could, in the long term, lead to new treatments for patients suffering from wounds that do not heal, a major public health challenge.