Mushrooms lingering on human skin can provide new antibiotics

Researchers from the University of Oregon have revealed a molecule produced by living yeast on human skin which has shown powerful antimicrobial properties against a pathogen responsible for half-million a year in the United States.

It is a unique approach to solving the growing problem of antibiotic resistant bacteria. With the global threat of drug -resisting infections, fungi living in human skin is an unexploited resource to identify new antibiotics, Caitlin Kowalski, a postdoctoral researcher at the UO, said the study.

Described in an article published in Current biologyThe fungus of the common skin Malassezia swallows oil and fats on human skin to produce fatty acids that selectively remove Staphylococcus aureus. One in three people has Staphylococcus Aureus lives safely in their noses, but bacteria are a risk factor for serious infections when they are given the opportunity: open wounds, abrasions and cuts. They are the main cause of skin infections and soft tissues called staphylococcus infections.

Staphylococcus aureus is also a notorious superbactful hospital to be resistant to current antibiotics, raising the urgent need of new drugs.

“There are many studies that identify new antibiotic structures,” said Kowalski, “but what was fun and interesting about ours is that we have identified (a compound) which is well known and that people have already studied.”

The compound is not toxic under normal laboratory conditions, but it can be powerful under conditions that reproduce the acidic environment of healthy skin.

“I think that is why in some cases, we may have missed this kind of antimicrobial mechanisms,” added Kowalski, “because the pH of the laboratory was not low enough. But human skin is really acidic.”

Humans welcome a colossal range of microorganisms, known as microbiome, but we know little about our resident mushrooms and their contributions to human health, Kowalski said. The cutaneous microbiome interests it particularly, because if other parts of the body widen dozens of different mushrooms, the skin is mainly colonized by a type known as Malassezia.

Malassezia can be associated with cases of dandruff and eczema, but it is considered relatively harmless and a normal part of the skin flora. The yeast has evolved to live on the skin of mammals, so much so that it cannot make fatty acids without lipids – oils and fats – secreted by the skin.

Despite the abundance of Malassezia that we find on us, they remain sub-studied, said Kowalski.

“Skin is a system parallel to what is happening in the intestine, which is really well studied,” she said. “We know that the intestinal microbiome can modify the host compounds and create their own unique compounds that have new functions. The skin is rich in lipids, and the skin microbiome deals with these lipids to also produce bioactive compounds. So, what does this mean for health and skin diseases?”

By looking at human skin samples from healthy donors and experiences made with laboratory skin cells, Kowalski found that Malassezia Sympolaris fungal species have transformed host lipids into hydroxy antibacterial acids. Fat acids have various functions in cells but are notably the constituent elements of cell membranes.

The hydroxy fatty acids synthesized by Malassezia Symporis were detergents, destroying the staphylococcus aureus membranes and causing the flight of its internal content. The attack prevented the colonization of Staphylococcus aureus on the skin and finally killed bacteria as 15 minutes, Kowalski said.

But the fungus is not a magic ball. After sufficient exposure, staphic bacteria finally become tolerant in the fungus, as they do when clinical antibiotics are overused.

Looking at their genetics, the researchers found that bacteria have changed a mutation in the REL gene, which activates the response to bacterial stress. Similar mutations have been previously identified in patients with staphylococcus aureus infections.

The results show that the host environment of a bacteria and interactions with other microbes can influence its sensitivity to antibiotics.

“There is an increasing interest in applying microbes as therapy, such as adding bacteria to prevent the growth of a pathogen,” Kowalski said. “But that can have consequences that we have not yet fully understood. Even if we know that antibiotics lead to the evolution of the resistance, this has not been considered when we consider the application of microbes as therapy.”

While the discovery adds a layer of complexity to discover drugs, Kowalski said that she was enthusiastic about the potential of resident fungi as a new source of future antibiotics.

The identification of antimicrobial fatty acids has taken three years and an interdisciplinary effort. Kowalski collaborated with chemical microbiologists from McMaster University to find the compound.

“It was like finding a needle in a hay boot, but with molecules, you cannot see,” said Kowalski advisor Matthew Barber, associate professor of biology at the College of Arts and Sciences at UO.

Kowalski works on a follow -up study that deepens genetic mechanisms that have led to antibiotic tolerance. She is also preparing to launch her own laboratory to investigate the neglected role of the skin microbiome, separating from the Barber laboratory after developing the mushrooms.

“Bacterial infections resistant to antibiotics are a major threat of human health and which, in some respects, Empire,” said Barber. “We still have a lot of work to do to understand microorganisms, and also find new ways that we can possibly treat or prevent these infections.”