We were surprised to find such potent antimicrobial activity from the common skin fungus Malassezia, which previously was only known to live harmlessly on human skin. This finding could one day lead to the creation of novel antibiotics, especially as we face increasing dangers from antibiotic-resistant infections. The research led by postdoctoral researcher Caitlin Kowalski is the first to show how Malassezia converts host lipids into hydroxy fatty acids. These acids in particular go after Staphylococcus aureus, a potentially dangerous bacterium often associated with life-threatening infections.
Malassezia is a very common, usually harmless fungus that lives on human skin. It thrives off the sebum and sweat on our skin. Fermentation produces fatty acids. We find that these fatty acids possess an extraordinary potency against Staphylococcus aureus. This bacteria is commonly found in the noses of about one-third of people and it isn’t harmful. This normally harmless bacterium can be very dangerous when it is just able to slip through the cracks like open wounds or cuts.
The Role of Malassezia in Skin Health
Malassezia acts as a commensal organism on human skin flora, known to be mostly harmless in general unless an abnormal shift occurs. It has been associated with dermatologic diseases including dandruff and eczema. Its ubiquity in the skin microbiome — a collective of microorganisms that help preserve skin health and defend against disease — makes it essential.
The study’s findings are particularly interesting, given that Malassezia sympodialis produces hydroxy fatty acids that work like detergents. These free fatty acids alter the integrity of the membranes of Staphylococcus aureus, causing the contents of its cells to leak out. This mechanism marks a new strategy on how we can fight against this widespread but sometimes deadly bacterium.
“We still have a lot of work to do in understanding the microorganisms, and also finding new ways that we can possibly treat or prevent those infections,” – Matthew Barber
This research highlights the multifaceted nature of the skin microbiome and its impact on human health. Since fungi are ignored in many ATOPIC studies, this new research shifts the spotlight to fungi, which are prevalent on human skin. Even with their widespread presence, fungi have been largely understudied compared to pathogenic bacteria.
Implications for Antibiotic Development
These newly discovered antimicrobial properties of Malassezia open a world of exciting new drug discovery opportunities. Antibiotic-resistant bacterial infections are one of the greatest and most urgent threats to public health today. Finding new sources of antibiotics is key to combating this escalating threat.
Kowalski’s study spanned three years and required a cross-disciplinary collaboration to determine the antimicrobial fatty acids that Malassezia produces. This new line of research introduces a pivotal new dimension to ongoing efforts to discover effective, non-antibiotic treatments for infections.
“Antibiotic-resistant bacterial infections are a major human health threat and one that in some ways is getting worse,” – Barber
The knowledge derived from understanding Malassezia could inform novel approaches to prevention and therapy of infection. Researchers believe that exploring the untapped resources within the human microbiome could reveal new compounds to combat resistant strains of bacteria.
Future Research Directions
Though this study marks an important milestone, researchers concede there is still much more to be accomplished. Further investigation into the microorganisms that inhabit human skin will be essential to fully understand their potential applications in medicine.
Kowalski highlights the importance of ongoing research, stating, “There are lots of studies that identify new antibiotic structures, but what was fun and interesting about ours is that we identified (a compound) that is well-known and that people have studied before.” This integrative approach will help uncover novel antimicrobial mechanisms that have not been identified in prior studies.
“I think that’s why in some cases we may have missed these kinds of antimicrobial mechanisms,” – Kowalski
Scientists are just beginning to understand the fascinating world of the skin microbiome. Their goal is to find new antimicrobial activities, information that will hopefully lead to the discovery of new, effective treatments for antibiotic-resistant infections.