Antibacterial activity of reduced iron clay against pathogenic bacteria associated with wound infections

Clay is a substance historically utilized by indigenous cultures for the treatment of superficial wound infections. This study evaluated the effects of a recently identified clay - OMT Blue Clay - against staphylococci, streptococci, Enterobacteriaceae and non-fermenting Gram-negative bacilli. The clay and its aqueous leachate were evaluated against the bacteria in biofilm and planktonic states. Time-kill studies were used to assess planktonic activity. Biofilms on medical-grade Teflon discs were treated with a hydrated clay suspension or leachate. For the planktonic studies, clay and leachate exhibited bactericidal activity against all strains tested, with the exception of leachate against Staphylococcus aureus IDRL-6169 and USA300. All strains treated with clay suspension and leachate resulted in statistically significant biofilm population reductions compared with controls, except S. aureus IDRL-6169 and USA300 (P ≤ 0.05). OMT Blue Clay and its aqueous leachate exhibited bactericidal activity against a range of human pathogens in the planktonic and biofilm states.