Research Projects:
Buruli ulcer (Mycobacterium ulcerans)/antibacterial properties of clay minerals
Overview | Project page
In 2002, a French humanitarian described the use of clay minerals as a therapeutic treatment of Buruli ulcer. However, without scientific research and validation, her efforts to use clay minerals in medicinal applications for treating Buruli ulcer were not supported by the WHO. Recently, there have been several reports describing the antibacterial properties of clay minerals. Despite the advent of these studies and the clinical evidence suggesting that clay minerals promote healing in individuals infected with M. ulcerans, the chemical interaction occurring at the clay mineral-bacterial interface and the precise mechanism by which the clay minerals are inhibiting bacterial growth remains unknown. Our lab aims to investigate the mechanism(s) by which specific clay minerals can kill bacteria.
Assess the broad-spectrum antibacterial effects of specific clay minerals and mineral derivatives
In order to understand how natural minerals are effective at inhibiting bacterial growth, we have subjecting various bacterial pathogens to antimicrobial susceptibility testing. We have subjected the two iron-rich clay minerals, which were used to treat Buruli ulcer patients, to broth culture susceptibility testing of antibiotic-susceptible and antibiotic-resistant pathogenic bacteria to assess the feasibility of using clay minerals as therapeutic agents. One specific mineral, CsAg02, demonstrated bactericidal activity against b-lactamase (ESBL) E. coli, S. enterica serovar Typhimurium, Pseudomonas aeruginosa, and Mycobacterium marinum and a combined bacteriostatic/bactericidal effect against Staphylococcus aureus, penicillin-resistant S. aureus (PRSA), methicillin-resistant S. aureus (MRSA), and Mycobacterium smegmatis, while another mineral with similar structure and bulk crystal chemistry, CsAr02, had no effect on or enhanced bacterial growth. The results of these experiments are presented in the following manuscript:
Haydel, S. E., C. M. Remenih, L. B. Williams. 2008. Broad-spectrum in vitro antibacterial activities of clay minerals against antibiotic-susceptible and antibiotic-resistant bacterial pathogens. J. Antimicrob. Chemother. 61:353-361.
We have continued to investigate the antimicrobial properties of clay minerals and have subjected more than 20 clay minerals to susceptibility testing of a variety of bacteria to determine if clay minerals could be used as inexpensive, topical therapeutic agents. We have identified two additional minerals that can kill or significantly reduce the growth of bacteria, including pathogenic Escherichia coli, antibiotic-resistant E. coli, Salmonella, and methicillin-resistant Staphylococcus aureus (MRSA).
Microorganisms:
Escherichia coli
ESBL (antibiotic-resistant) Escherichia coli
Escherichia coli O157:H7
Salmonella enterica serovar Typhimurium
Salmonella enterica serovar Enteritidis
Campylobacter jejuni
Pseudomonas aeruginosa
ESBL (antibiotic resistant) Klebsiella pneumoniae
Neisseria gonorrhoeae
Staphylococcus aureus
Streptococcus pneumoniae
Streptococcus pyogenes
Enterococcus faecalis
Vancomycin-resistant Enterococcus faecalis (VRE)
Mycobacterium smegmatis
Mycobacterium marinum
Mycobacterium fortuitum
Mycobacterium ulcerans
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Determine the microbiological mechanism(s) by which natural nanominerals promote bacteriostatic or bactericidal activity
We are investigating the possible mechanism by which the clays kill bacteria by assessing potential physical damage to the bacterial cells and cellular physiological damage caused by the chemical properties of the the clay minerals.
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Evaluate the effectiveness of antibacterial clay poultices and nanomineral-derived solutions to promote healing
The long-term goal of this research is to validate mineral applications for the treatment of Buruli ulcer patients and to develop a new broad-spectrum antibacterial product for cutaneous infections that are difficult to treat due to ineffecient antibiotics, innate or acquired resistance, or the requirement of an extended treatment regimen. Our objective is to evaluate the in vivo efficacy of clay minerals and mineral solutions in the experimental treatment of topical infections.
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