Although it is less well known than antibiotic resistance, antifungal resistance is also an expanding problem. Particular fungi have always been hard to treat, but, increasingly, some that were once easy to manage are becoming ever more difficult to tackle. For instance, the very common fungus Candida, which can cause invasive infections, is starting to become immune to conventional antifungals. So, the race is on to design antifungal drugs that can circumnavigate this medical conundrum. One new and surprising contender is nylon.
A new antifungal?
Over recent years, researchers from the University of Wisconsin-Madison have been investigating nylon polymers’ ability to fight fungi. The authors of the new study, which was led by Nancy Keller, wanted to locate a compound that would interact with the fungus in the same way that peptides in the immune system do. Peptides are short chains of amino acids, so the team looked at other short chain molecules, and they settled on nylon. Keller decided to join forces with microbiologist Christina Hull and chemist Samuel Gellman, who had previously developed polymers for use as antibiotics. Together, they sought to understand whether the polymers could be as successful against fungi as they had been against bacteria. Three nylon polymers were pitted against 41 species of fungi. They compared their fungus-killing ability against azoles, a common class of antifungal drug. The researchers were pleasantly surprised at the polymers’ success rates. The nylon polymers halted the growth of 24 species, some of which are already resistant to azoles. “The fungi are very spread out, in a biochemical way. There was no way of predicting the polymers would be active against such a wide breadth of taxa.” The species of fungi that were successfully destroyed include Rhizopus arrhizus, which can cause life-threatening conditions in at-risk individuals, and Scedosporium prolificans, which can cause fatal infections and is impervious to existing antifungals. However, not all fungi species succumbed. Notably, Aspergillus a fungus that can cause serious lung conditions in susceptible people did not respond.
A synergistic boost
Interestingly, the team found that when the polymers were used alongside azoles, fungi that were previously azole-resistant once again became susceptible to the drug. This offers a new potential treatment option; for fungi that respond to neither the polymers nor standard antifungals, it might be worth using them in unison. Modern medicine rarely uses polymers in this way, and Gellman is excited by the possibilities they offer. He says, “Observations of this type should encourage the community to consider polymers as potentially useful biomedical agents.” How the polymers fight fungi is unclear. As Gellman puts it, “We don’t really know how they work.” The next phase of research will make efforts to dig into the mechanisms behind it. Additionally, because polymer use in medicine is a fledgling technology, no one knows how many powerful polymers there are out there, waiting to be designed and tested. As Gellman concludes, “There are more structures than we can imagine.”
Medical News Today, 25 May 2018 ;