Fighting antibiotic-resistant microbes is one of the great challenges of our time. Lack of investment in the field and overuse of the drugs in farming have created a time bomb, and researchers worldwide are looking for an effective solution.

A team from Arizona State University (ASU) and Mayo Clinic have found that a particular type of blue clay from Oregon is effective at killing bacteria that have become drug-resistant. The effectiveness was only demonstrated in the lab, so it is still very early days, but the research is nevertheless encouraging.

As reported in the International Journal of Antimicrobial Agents, the clay was shown to be effective against common pathogens such as Escherichia coli and Staphylococcus aureus. This included tough-to-kill strains like carbapenem-resistant Enterobacteriaceae and methicillin-resistant Staphylococcus aureus (MRSA).

"Working with Mayo Clinic, we showed that these clays also diminish populations of bacterial biofilms, as well as bacteria common in wounds that are more resistant to drugs," co-author Lynda Williams, a biochemist at ASU, said in a statement. "The results support our efforts to design new antibacterial drugs using natural clays."

Biofilms are a particularly thorny issue of drug development. These slimy substances are produced by microorganisms when they are aggregating in a community. The presence of these structure makes them even harder to attack and defeat. The clay was effective at wiping out bacteria both with and without biofilms.

"We showed, however, 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," added Robin Patel, an infectious disease physician and clinical microbiologist at Mayo Clinic, and lead author of the study.

The inspiration for this study came from the common use of clays as topical skin treatments in many cultures. The researchers were curious to see if antibacterial properties could be confirmed in certain kinds of muds. The team made a suspension using the blue clay but only tested one particular concentration. Therefore, it is important to remain a little cautious about the findings. 

At least 23,000 people die in the US every year from antibiotic-resistant infections, with around 2 million becoming infected. The United Nations (UN) estimates that drug-resistant pathogens could kill 10 million people worldwide each year by 2050.