Harnessing a natural geochemical reaction to combat antibiotic resistance

Researchers at Lawrence Livermore National Laboratory (LLNL) are exploring alternative treatment options when antibiotics fail. Certain naturally occurring clay deposits have been shown to harbor antimicrobial properties and kill antibiotic-resistant bacteria. These clays have been proposed as a new paradigm for fighting the potentially devastating effects of the post-antibiotic era.

Despite their effectiveness, these naturally occurring clays, by their inherent heterogenous properties, exhibit variable antibacterial effectiveness and the synthesis of minerals with reproducible antibacterial activity is needed to harness their therapeutic value.

A team of LLNL geochemists, cell biologists and microbiologists set out to produce fully synthetic versions of the naturally occurring antibacterial minerals, while controlling the purity and reactivity of the compounds. The minerals linked to the antibacterial activity of natural samples are smectite clay minerals and iron (Fe)-sulfides (pyrite). The research team, led by Keith Morrison, used hydrothermal reactors to synthesize chemically pure mineral end members that had the correct particle size, surface charge and reactivity of natural samples.

The synthetic antibacterial minerals were tested against the ESKAPE pathogens: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter, which represent the most common group of human pathogens that "escape" the effects of antibiotics in clinical settings. "Our results indicate that bacterial pathogens can be killed by the synthetic clays in as little as one hour depending on the dose." Morrison said.