According to researchers, fungi found in chronic wounds such as diabetic foot ulcers can form biofilms made from a mix of bacteria and fungi, and can be associated with poor outcomes and longer healing times.

The researchers—senior author Elizabeth Grice, assistant professor of dermatology and microbiology at the University of Pennsylvania, along with postdoctoral researcher Lindsay Kalan—followed 100 patients with diabetic foot ulcers for 26 weeks, or until the wound healed or required amputation, per a media release from the American Society for Microbiology.

During the patients’ care, samples of their deep wound fluid were taken every 2 weeks and were given to Grice and Kalan for genetic sequencing and identification of the fungi.

The duo found that 80% of the wounds harbored fungi from 284 different species. The most abundant fungus, Cladosporium herbarum, was found in 41% of the samples, and next most abundant fungus, the human pathogen Candida albicans, was found in a little over 20% of the samples.

No single species of fungi was associated with poor outcomes, but rather mixed communities were associated with slow healing or complications such as bone infection and amputation. However, higher levels of ascomycetes, or sac fungi, at the initial swabbing were associated with wounds that took longer than 8 weeks to heal, the release explains.

To see whether the microbes in the wounds could grow biofilms, which are thought to keep many chronic wounds festering, Kalan isolated the C. albicans yeast and Citrobacter freundii bacteria from a patient whose wound eventually healed, and she isolated the fungus Trichosporon asahii and bacteria Staphylococcus simulans from a patient whose wound resulted in an amputation. When she co-cultured these bacterial-fungal pairs in the laboratory, she found that both pairs formed a mixed biofilm, the release continues.

“Lindsay showed very nicely that the fungi interact with the bacteria, potentially making biofilms within wounds,” Grice says in the release. “You can’t properly target treatment if you are missing that critical interaction.”

“There are polymicrobial interactions within these wounds,” Kalan adds. “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.”

Their study was published recently in mBio, an open-access journal of the American Society for Microbiology.

[Source(s): American Society for Microbiology, Science Daily]