For centuries, various cultures have used clay as a remedy for infections. Now, scientists from Arizona State University (ASU) and the Mayo Clinic have determined that blue clay in particular may indeed be effective at treating infected wounds.

The study builds on previous ASU research, which indicated that the chemically-reduced iron and aluminum in blue clay from Oregon was capable of killing free-floating bacteria. In the new study, a solution containing the clay was also shown to be effective when used on biofilms made up of harmful bacteria such as Escherichia coli and Staphylococcus aureus.

Basically self-supporting colonies of bacteria, such biofilms are present in about two thirds of infected wounds seen by physicians. Because they take the form of a coating that protects the microbes within, they're often resistant to antibiotics.

"We showed that this reduced iron-bearing clay can kill some strains of bacteria under the laboratory conditions used, including bacteria grown as biofilms, which can be particularly challenging to treat," says the Mayo Clinic's Dr. Robin Patel, senior author of the study.

That said, the researchers note that not all types of clay may be effective, and that only one concentration of the blue clay solution has been tested so far. Down the road, they hope to produce a synthetic compound that stably and consistently offers the therapeutic effects of the key minerals that are found naturally in the clay.

A paper on the research was recently published in the International Journal of Antimicrobial Agents.

Scientists from the University of British Columbia have previously had success in using Kisameet clay to kill bacteria.

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