VANCOUVER - Researchers at the University of B.C. have discovered that a rare clay used as medicine by aboriginals in northern B.C. contains antibacterial properties that could be used to treat antibiotic-resistant bacteria.

Some 400 kilometres north of Vancouver, on the Heiltsuk First Nation's traditional territory, sits a 400-million kilogram deposit of glacial clay in Kisameet Bay that scientists believe was formed near the end of the last Ice Age, approximately 10,000 years ago.

The grey-green clay, known as Kisolite, has been used for centuries by the Heiltsuk First Nations to treat a range of ailments, including ulcerative colitis, arthritis, neuritis, phlebitis, skin irritation, and burns. Locals have also historically used the clay for eczema, acne and psoriasis.

Now, UBC researchers say the clay exhibits potent antibacterial activity against multidrug-resistant pathogens.

Testing conducted by UBC microbiologist Julian Davies and researcher Shekooh Behroozian found that the clay, suspended in water, killed 16 strains of ESKAPE bacteria samples from sources including Vancouver General Hospital, St. Paul's Hospital, and the University of B.C.'s waste water treatment plant.

As a result of those tests, the scientists recommend the clay be studied as a clinical treatment for serious infections caused by ESKAPE strains of bacteria, a group of potentially deadly pathogens that cause many infections to "escape" antibiotics.

"Infections caused by ESKAPE bacteria are essentially untreatable and contribute to increasing mortality in hospitals," said Davies, the co-author of a paper published Tuesday in the American Society for Microbiology's mBio journal.

The research team was approached three years ago by Kisameet Glacial Clay, a company formed to market cosmetic and medicinal products made from the clay.

"They wanted microbial testing on clay, so I was a bit skeptical at first," Davies said in an interview Tuesday. "Well, there are all sorts of claims out there, all kinds of folklore medicine and witchcraft."

However, Davies and Behroozian were surprised to discover that properties in the leachate derived from the clay killed all of the 16 strains of bacteria tested.

He said after 50 years of over-using antibiotics, ancient medicinals and other natural mineral-based agents may provide new weapons in the battle against multi-drug-resistant pathogens.

Davies said no toxic side effects have been reported from the use of the clay. So the next stage in clinical evaluation would involve detailed clinical studies and testing on animals.

He said the anti-bacterial properties would be extracted from the mud and would likely be either injected into the subject, or administered using a patch.

Researchers also need to further study the mode of action to understand how the clay works to destroy bacteria.

The research was partly funded by Kisameet Glacial Clay. The company says the colloidal glacial clay from a shallow five-acre granite basin, nine-metres above sea level, is hand-harvested by local Heiltsuk contractors. The company has a memorandum of understanding with the Heiltsuk First Nation concerning extraction rights.

Kisameet Glacial Clay would like to begin marketing a line of cosmetic products, but does not want to until the healing properties can be scientifically proved, said company president Lawry Lund.