June 26, 2014
Fungus Discovered That May Stop Superbugs Dead In Their Tracks
Rebekah Eliason for redOrbit.com – Your Universe Online
For several years, concern about antibiotic resistant drugs has been increasing. Scientists have recently discovered a fungus in Nova Scotia that offers hope against the growing health threat that kills tens of thousands every year.The team, from McMaster University, has isolated a fungus-derived molecule, known as AMA, which has the ability to disarm NDM-1, which is one of the most dangerous antibiotic resistant drugs.
"This is public enemy number one," explains Gerry Wright, director of the Michael G. DeGroote Institute for Infectious Disease Research at McMaster University.
"It came out of nowhere, it has spread everywhere and has basically killed our last resource of antibiotics, the last pill on the shelf, used to treat serious infections," he says.
Arriving at a critical time, this fungus-derived molecule proved the means to rapidly block and target the drug resistant pathogens. Specifically, this molecule helps replace carbapenem antibiotics, which are similar to penicillin.
"Simply put, the molecule knocks out NDM-1 so the antibiotics can do their job," says Wright.
For decades scientists have been searching to discover a new stronger set of antibiotics, but looking for the solution in the natural environment is much more promising. No new classes of antibiotics have been discovered since late in the 1980s. Consequently, physicians have been left with few tools to fight the dangerous life-threatening infections.
"Not only do we have the emergence of an antibiotic resistance gene that is targeting the last drug resource we have left, but it is carried by organisms that cause all sorts of challenging diseases and are multi-drug-resistant already. It has been found not only in clinics but in the environment—in contaminated water in South Asia—which has contributed to its spread over the globe," explains Wright. "Our thinking was that if we could find a molecule that blocks NDM-1 then these antibiotics would be useful again."
For this study, Wright and the team from McMaster University of British Columbia and Cardiff University in Wales designed an intricate screening method. First they isolated the NDM-1 gene and then combined it with a strand of harmless E. coli bacteria. This enabled them to isolate a molecule capable of defeating NDM-1.
To thrive, NDM-1 requires zinc, but it is extremely difficult to remove zinc without causing a disastrous toxic effect for humans. Excitingly, this molecule appears to stop NDM-1 naturally and harmlessly.
After discovering the molecule, the team tested the new finding on mice that were infected with an NDM-1 expressing superbug. Mice treated with both the AMA molecule and a carbapenem antibiotic survived, but those only receiving one of the treatments were not able to survive the infection.
"This will solve one aspect of a daunting problem. AMA rescues the activity of carbapenem antibiotics, so instead of having no antibiotics, there will be some," says Wright. "This is a made-in-Canada solution for a global problem."
"Antibiotic resistance may be the most urgent and perplexing challenge facing health-care researchers today," says Dr. John Kelton, dean of the Michael G. DeGroote School of Medicine and vice-president of the Faculty of Health Sciences at McMaster. "This research provides new hope by showing us a completely new way to approach this problem, and none too soon, given the growing risk that superbugs pose to all of us."
"Antibiotic resistance is one of the top public health concerns in Canada and internationally and it represents a research priority for the Canadian Institutes of Health Research (CIHR). It is exciting to see Canadian researchers finding innovative strategies to overcome antimicrobial resistance," says Dr. Marc Ouellette, scientific director of the CIHR Institute of Infection and Immunity.
This study was published online in the journal Nature.