NEW ORLEANS, April 6, 2008 — Mud may be coming to a medicine cabinet or pharmacy near you. Scientists in Arizona report that minerals from clay could form the basis of a new generation of inexpensive, highly-effective antimicrobials for fighting MRSA infections that are moving out of health care settings and into the community. These "superbugs" are increasingly resistant to multiple antibiotics and cause thousands of deaths each year.
Unlike conventional antibiotics that are often administered by injection or pills, the so-called "healing clays" could be used as rub-on creams or ointments to keep MRSA infections from spreading, the researchers say. The clays also show promise against a wide range of other harmful bacteria, including those that cause skin infections and food poisoning, the scientists add. Their study, one of the first to explore the antimicrobial activity of natural clays in detail, was presented today at the 235th national meeting of the American Chemical Society.
Clays have been used for thousands of years as a remedy for infected wounds, indigestion, and other health problems, either by applying clay to the skin or eating it. Today, clays are commonly used at health spas in the form of mud baths and facials. Armed with new investigative tools, researchers are beginning to explore their health claims scientifically.
"Clays are little chemical drug-stores in a packet," said study co-leader Lynda Williams, Ph.D., a geochemist at Arizona State University in Tempe. "They contain literally hundreds of elements. Some of these compounds are beneficial but others aren't. Our goal is to find out what nature is doing and see if we can find a better way to kill harmful bacteria."
In the new study, funded by the National Institutes of Health, Willams and her colleagues collected more than 20 different clay samples from around the world to investigate their antibacterial activities. In collaboration with study co-leader Shelley Haydel, Ph.D., a microbiologist with Arizona State, the researchers tested each of the clays against several different bacteria known to cause human diseases. These bacteria include MRSA (methicillin-resistant Staphylococcus aureus), Mycobacterium ulcerans (a microbe related to the tuberculosis bacterium that causes a flesh-eating disease known as Buruli ulcer), as well as E. coli and Salmonella (which cause food poisoning). The researchers identified at least three clays that killed or significantly reduced the growth of these bacteria.
The researchers are working to identify the specific compounds in the clays that may be responsible for its antibacterial activity. Using electron and ion microscopy, the researchers are also exploring how these antibacterial clays interact with the cell membranes of the bacteria in order to find out how they kill.
Williams and Haydel are continuing to test new clay samples from around the world to determine their germ-fighting potential. They hope that the more promising clays will be developed into a skin ointment or pill to fight a variety of bacterial infections or possibly as an agricultural wash to prevent food poisoning. Several companies have expressed interest in forming partnerships to develop the clays as antimicrobial agents, the scientists say.
But ordinary mud can contain dangerous bacteria as well as toxic minerals like arsenic and mercury, the researchers point out. Until healing clays are developed that are scientifically proven, which could take several years, handwashing and other proper hygiene techniques may be your best bet for keeping MRSA and other harmful bacteria at bay, they say. The American Chemical Society — the world's largest scientific society — is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.
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The papers on this research, GEOC 022 and GEOC 025, will be presented at 2:30 p.m. and 4:10 p.m., respectively, on Sunday, April 6, at the Morial Convention Center, Room 213, during the symposium, "Clay Minerals and Health."
A poster on this research, GEOC 163, will be presented at 6:00 p.m., Wednesday, April 9, at the Morial Convention Center, Hall A, during the symposium, "General Geochemistry and Clay Minerals Society Poster Session."
Lynda Williams, Ph.D., is an Associate Research Professor in the School of Earth and Space Exploration at Arizona State University, Tempe, Arizona.
Shelley Haydel, Ph.D., is an Assistant Professor in the School of Life Sciences and a researcher in the Center for Infectious Diseases and Vaccinology at the Biodesign Institute at Arizona State University, Tempe, Arizona. ALL PAPERS ARE EMBARGOED UNTIL DATE AND TIME OF PRESENTATION, UNLESS OTHERWISE NOTED The paper on this research, GEOC 022, will be presented at 2:30 PM, Sunday, April 6, 2008, during the symposium, "Clay Minerals and Health." GEOC 022Comparing antibacterial clay properties in search of new medicinal applications Program Selection: Division of GeochemistryTopic Selection: Clay Minerals and Health
Abstract Healing clays have been used for health since recorded history. The method of healing varies from toxin absorption on clay surfaces to supply of nutrients. Recently we have identified a few antibacterial clays shown to be effective in killing several Gram-negative, Gram-positive and mycobacterial species. The mechanism of killing is being investigated as a potential design for new antibacterial agents.
Over 20 clays were tested against bacteria grown in aqueous suspensions. The clay mineralogy (XRD), chemistry (EM and ICP-MS) and texture (FESEM) of the antibacterial clays are diverse, however they all have extreme pH values. The pH and Eh may be buffered by the clays and may control the speciation of metals in the aqueous transfer to bacteria. The aqueous chemical speciation is as important as the minimum inhibitory concentrations of elements involved in reactions that might impede metabolic functions of various pathogenic bacteria. ________________________________________Researcher Provided Non-Technical Summary Briefly explain in lay language what you have done, why it is significant and what are its implications (particularly to the general public)
This work was conducted because of the observation that certain clay minerals heal infections, while others do not. Having identified several antibacterial clays, we have tested the chemical, mineralogical and surface properties of the clays against a broad spectrum of bacterial species, including antibiotic resistant strains of S. Aureus (MRSA and PRSA). Using an electron microscope, we have imaged the interaction of the clay and bacteria, monitoring the cell morphology and chemical changes during bactericide. These data will help us to deduce the antibacterial mechanism of clays, with the goal of identifying new types of antibacterial agents useful against bacteria that have evolved resistance to current antibiotics.
How new is this work and how does it differ from that of others who may be doing similar research?
People around the world have used clays as a remedy for indigestion, intestinal ailments and wounds since the beginning of recorded history. Only recently have scientists had the appropriate analytical tools to start studying the science behind these remedies. Several researchers worldwide are involved in studying the antibacterial properties of clay minerals. I am presenting the results of a small portion of a study funded by the National Institutes of Health to identify antibacterial properties of clay minerals used to heal skin infections.
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American Chemical Societyâ€™s 235th national meeting