Fungal Communities May Prevent Diabetic Wound Healing

Fungi and bacteria in chronic wounds can cause mixed biofilms that prevent healing.

Findings from a recent study suggest that fungi found in chronic wounds can cause poor health outcomes and longer healing times, especially for patients with diabetic foot ulcers.

Fungal communities found in the wounds can create mixed bacterial-fungal biofilms in the wounds that prevent healing.

Researchers in the study, published by mBio, followed 100 patients with diabetic foot ulcers for 26 weeks, until the wound healed, or until amputation was required.

“Chronic wounds are a silent epidemic,” said senior author of the study Elizabeth Grice, PhD. “They usually occur in conjunction with another disorder such as diabetes or obesity, but once a chronic wound occurs, it requires a lot of healthcare and has a devastating effect on a patient's quality of life."

Millions of patients with diabetes develop a diabetic ulcer in their lifetime, and many require amputation, which can cost the healthcare system billions of dollars per year. Other scientists have created an experimental regenerative bandage that could potentially speed up healing and prevent amputations. However, nothing like that is currently available to patients.

In the current study, all patients with ulcers received the same care, and researchers obtained deep wound fluid from the patients every 2 weeks. The fluid was genetically sequenced, and then the fungi was identified.

There were 284 different species found in 80% of diabetic wounds, according to the study. Cladosporium herbarum was the most common fungus, and was found in 41% of samples.

Candida Albicans was the second most common fungus, and was found in more than one-fifth of the samples. Interestingly, no single species was associated with poor outcomes, but the mixed communities contributed to slow healing, bone infection, amputation, and other complications, according to the study.

Wounds with high levels of ascomycetes (sac fungi) during the first swabbing took 8 weeks longer to heal. This suggests that physicians may be able to predict healing time from swabs.

Investigators also looked at 2 patients’ wounds specifically, to determine whether their communities of fungi would grow biofilms that are thought to assist festering of the wound.

C. albicans yeast and Citrboacter feundii bacteria were isolated from a patient with a wound that healed. Trichosporon asahii fungus and Staphylococcus simulans bacteria were isolated from a patient whose wound resulted in amputation, according to the study.

By co-culturing the pairs, the investigators found that they formed a mixed biofilm.

“You can't properly target treatment if you are missing that critical interaction,” Dr Grice said.

The researchers said their findings are an initial step toward understanding and treating chronic wounds more effectively.

“There are polymicrobial interactions within these wounds,” said researcher Lindsay Kalan, PhD. “It's important to look at the fungal and bacterial communities and how they interact with each other and the immune system to impair or promote healing.”